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Why do Mangoes have a single large seed, and not multiple small ones?

Why do Mangoes have a single large seed, and not multiple small ones?


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I was just thinking about this, wouldn't it make more sense for a mango to have multiple seeds, as it would allow more seed propagation?


It is an interesting question and it applies to other fruits with big seeds as the avocado as well. It is very likely that these fruits evolved to be spread by large animals (like big birds or large mamals) which existed for a relatively long time, but are extinct today. These animals swallowed whole fruits and excreted the seeds afterwards (most of these seeds are slighty laxative) together with dung to support the growth.

They are called "evolutionary anachronisms" and there is a very interesting book about them, called "The ghosts of evolution: nonsensical fruit, missing partners, and other ecological anachronisms." (which can be found as a PDF online) Two interesting articles about this phenomenon can be found here:


Reproduction in Organisms Important Extra Questions Very Short Answer Type

Question 1.
What is the life span?
Answer:
The period from birth to natural death of an organism is termed its life span.

Question 2.
Why is reproduction essential for organisms?
Answer:
Reproduction is a process by which an organism produces young ones of its own kind to maintain the continuity of the species. It enables the species to live generation after generation.

Question 3.
What type of modification are ginger, potato, onion and Samarkand?
Answer:
Underground modification of stem.

Question 4.
Name sub-aerial stems which help in multiplication.
Answer:
Pistia, Chrysanthemum Eichhornia, Pineapple.

Question 5.
Name artificial methods of vegetative propagation.
Answer:

Question 6.
Which type of division is involved in asexual reproduction?
Answer:
Only mitotic division occurs during asexual reproduction.

Question 7.
Male honeybee has 16 chromosomes whereas its female has 32 chromosomes. Give one reason. (CBSE Outside Delhi 2016)
Answer:
Male honey bee develops from haploid unfertilised egg (Ovum), whereas female develops from the diploid fertilized zygote.

Question 8.
The diploid number of chromosomes in an angiospermous plant is 16. What will be the number of chromosomes in its endosperm and antipodal cells? (CBSE Outside Delhi 2019)
Answer:
Number of chromosomes in endosperm = 24 (3N)
Number of chromosomes in antipodal cells = 8(N)

Question 9.
Banana is a true fruit and also a parthenocarpic fruit. Justify. (CBSE Foreign 2008)
Answer:
Banana develops from the ovary (true fruit) and develops without fertilisation (parthenocarpic fruit).

Question 10.
Pick out the ancestral line of angiosperms from the list given below: Conifers, seed ferns, cycads, ferns. (CBSE 2008)
Answer:
Seed ferns.

Question 11.
Why is apple referred to as false fruit? (CBSE 2010)
Answer:
In the case of apple, thalamus contributes to fruit formation, while most of the plant’s fruit develops from the ovary.

Question 12.
Name the type of cell division that takes place in the zygote of an organism exhibiting haplontic life cycle. (CBSE 2011)
Answer:
Meiosis

Question 13.
Mention the unique flowering phenomenon exhibited by Strobilanthus Ludhiana (Neelakuranji). (CBSE 2012)
Answer:
It is a monocarpic flowering plant. It flowers once in 12 years.

Question 14.
Some flowers, selected for artificial hybridisation, do not require emasculation but bagging is essential for them. Give a reason. (CBSE Delhi 2019 C)
Answer:
Bagging is the covering of flower by butter paper on polythene. The emasculated flower buds of the female parent and floral buds or male parent are bagged in order to protect them from contamination with unwanted pollen grains.

Question 15.
Cucurbits and papaya plants bear staminate and pistillate flowers. Mention the categories they are put under separately on the basis of the type of flowers they bear. |HOTSj (CBSE 2012)
Answer:
Cucurbits-Monoecious plants Papaya-Dioecious plants.

Question 16.
Why is banana considered a good example of parthenocarpy? (CBSE 2011)
Answer:
It is propagated vegetatively because there is no seed formation.

Question 17.
Name an alga that reproduces asexually through zoospores. Why are these reproductive units called so? (CBSE Outside Delhi 2013)
Answer:

Question 18.
Name the phenomenon and one bird where the female gamete directly develops into a new organism. (CBSE Outside Delhi 2013)
Answer:

Question 19.
Name the vegetative propagules in the following: (CBSE 2014)
(a) Agave
Answer:
Bulbils

(b) Bryophyllum.
Answer:
Leaf bud

Question 20.
Mention a characteristic and a function of zoospores in some algae. (CBSE 2010)
Answer:

  • Zoospores are microscopic and flagellated motile spores.
  • They are reproductive structures.

Reproduction in Organisms Important Extra Questions Short Answer Type

Question 1.
Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.
Answer:
No, there is no relationship between size and life span of organisms. Large-sized tiger and small-sized dog both live for about 20 years. The very large-sized elephant has a life span of up to 90 years. On the other hand, small-sized tortoise lives for 200 years. Similarly, the mango tree has a much shorter life span as compared to peep at the tree.

Question 2.
Offspring formed due to sexual reproduction have better chances of survival. Why?
Answer:
The offspring formed due to sexual reproduction show variations due to crossing over during gametogenesis, random segregation of gametes or random fertilisation. These useful variations produced in offspring help the organisms to adapt and survive.

Question 3.
How are the progeny formed from asexual reproduction different from those formed by sexual reproduction?
Answer:
The progeny formed from asexual reproduction is genetically similar to the parent, while those formed by sexual reproduction are genetically different from the parents due to new gene combinations formed during crossing over, random segregation and fertilisation.

Question 4.
Mention two inherent characteristics of Amoeba and yeast that enable them to reproduce asexually.
Answer:

  1. Amoeba and yeast are unicellular organisms.
  2. Both have a very simple body structure.
  3. Both reproduce by fission.

Question 5.
Why do we refer to offspring formed by the asexual method of reproduction as clones?
Answer:
Offspring formed by asexual reproduction are called clones because they are morphologically and genetically similar to the parent.

Question 6.
Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Answer:
Higher organisms have resorted to sexual reproduction in spite of its complexity because, at the same time, sexual reproduction provides two-fold advantages:

  1. Here genetic recombination, interaction, etc. take place which causes variations in the offspring thus also form raw materials for evolution.
  2. The offspring adapt more comfortably and quickly to the changes in the environmental conditions.

Question 7.
What are gemmules and conidia? Name one organism each in which these are formed. (CBSE Sample Paper 2019, 20)
Answer:
Gemmules: These are internal buds. They consist of a small group of archaeocytes, enclosed by a protective coat. They are formed in freshwater sponges e.g. Spongilla.

Conidia: They are formed in Penicillium. They are non-motile spores produced single or in the chain by a constriction at the tip of special hyphal branches called conidiophores.

Question 8.
Give examples of plants which are propagated vegetatively from underground stems and creeping stems.
Answer:
Underground stems. Mint and Chrysanthemum, Banana, Turmeric, Ginger, Aspidium, Adiantum. Creeping stems. Runners (mint, grass), stolons (strawberry) and offset (Eichhornia).

Question 9.
Differentiate between a zoospore and a zygote.
Answer:
Difference between a zoospore and a zygote:

Question 10.
List the pre-fertilisation events.
Answer:
Pre-fertilisation events. These include all the events of sexual reproduction prior to the fusion of gametes. The two main pre-fertilisation events are gametogenesis and gamete transfer.

Question 11.
Why does the zygote in angiosperms start developing into embryo only after some endosperm is formed?
Answer:
Zygote in angiosperms starts developing into embryo only after some endosperm is formed because endosperm is nutritive in function. It provides nutrients to the zygote for further growth and development.

Question 12.
Why is the offspring formed by asexual reproduction referred to as clone?
Answer:
The offspring formed by asexual reproduction is referred to as clone because the offspring is morphologically and genetically similar to the parent.

Question 13.
Mention the site where syngamy occurs in amphibians and reptiles respectively. (CBSE 2010)
Answer:

  1. In amphibians, syngamy occurs in the external medium, i.e. water.
  2. In reptiles, syngamy occurs in the body of an organism.

Question 14.
Why do internodal segments of sugarcane fail to propagate vegetatively even when they are in contact with damp soil? (HOTS) (CBSE Sample Paper)
Answer:
Sugarcane plants propagate vegetatively only when nodes are in contact with damp soil. Adventitious roots emerge from nodes and not from internodes because nodes bear buds.

Question 15.
Why do algae and fungi shift to a sexual mode of reproduction just before the onset of adverse conditions? (CBSE Delhi 2014, 2015)
Answer:
The organisms produced through asexual reproduction have low adaptability to the changing environment. Thus algae and fungi shift to a sexual mode of reproduction during the onset of adverse conditions.

Question 16.
A moss plant produces a large number of antherozoids but relatively only a few egg cells. Why? (CBSE 2010)
Answer:
In a moss plant, an antheridium produces many sperms while one archegonium produces only one egg cell. That is why there are a large number of antherozoids and a few egg cells.

Question 17.
Mention the reasons for the difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. (CBSE 2010)
Answer:
A zygote is diploid (2n) as one male gamete fuses with egg or oosphere, while primary endosperm nucleus is triploid as one male gamete fuses with a secondary nucleus which is already diploid.

Question 18.
In haploid organisms that undergo sexual reproduction, name the stage when meiosis occurs. Give reasons for your answer.
Answer:
Haploid organisms form gametes without meiosis. Mate and female gametes fuse to form a diploid zygote. Zygote being diploid undergoes meiosis to form haploid organisms e.g. Ulothrix, Chlamydomonas.

Question 19.
Describe the importance of syngamy and meiosis in the life cycle of an organism. (CBSE Delhi 2016)
Answer:
Syngamy is a fusion of haploid gametes. It restores diploid nature in the zygote. Meiosis occurs during gametogenesis, thus produces haploid gametes. Both are important for maintaining chromosome number (ploidy) in an organism.

Question 20.
Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each. (CBSE Delhi 2016)
Answer:
In dioecious plants, male flowers termed a staminate flower, and female flowers, termed as pistillate flowers, are borne on different plants. Thus plants are either male or female.

Examples: Papaya, date palm, etc.
In monoecious plants, male and female flowers are present on the same plants. Example: Maize, coconut, cucurbits, etc.

Question 21.
Write the significance of meiocytes. (CBSE (Delhi) 2016)
Answer:
Significance of meiocytes. Meiocytes are gamete-producing cells which undergo meiosis. They are diploid. As a result of meiosis, they produce haploid gametes. During fertilisation, a fusion of haploid gametes restores diploid nature of zygote. It undergoes mitosis to form complete new young one.

Question 22.
Why do organisms like algae and fungi shift from asexual mode of reproduction to sexual mode? (CBSE Delhi 2018C)
Answer:
During favourable conditions, organisms opt for asexual reproduction but when the conditions are adverse or unfavourable, organisms undergo sexual reproduction.

Question 23.
What is a juvenile phase in organisms? (CBSE Delhi 2018C)
Answer:
It is the stage of growth and attaining maturity in their life before they can reproduce sexually. It is also called the vegetative phase.

Question 24.
(i) State the difference between meiocyte and gamete with respect to chromosome number.
Answer:
Meiocytes are diploid (2n) and gametes are haploid.

(ii) Why is a whiptail lizard referred to as parthenogenetic? (CBSE 2012)
Answer:
Whiptail lizard eggs develop without fertilisation

Reproduction in Organisms Important Extra Questions Long Answer Type

Question 1.
Define:
(i) juvenile phase,
Answer:
Juvenile phase. The period of growth in the life of organisms before they start reproducing sexually and attain a level of maturity is called juvenile phase. It is followed by the reproductive phase.

(ii) reproductive phase
Answer:
Reproductive phase. The period of active reproductive behaviour, when the organisms show marked morphological and physiological changes is called reproductive phase. It is followed by senescence phase.

(iii) senescence phase.
Answer:
Senescence phase. The period when the reproductive phase ends and concomitant changes occur in the body such as slowing of metabolism is called senescence phase. It is followed by death.

Question 2.
Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?
Answer:
1. Differences between asexual reproduction and sexual reproduction.

Asexual Reproduction Sexual Reproduction
1. The process involves only one cell or one parent. 1. This process involves two cells or gametes belonging to either the same or different parents.
2. The whole body of the parent may act as a reproductive unit or it can be a single cell or a bud. 2. The reproductive unit is called gamete which is unicellular and haploid.
3. The offspring are genetically similar to the parent. 3. The offspring differ from the parents.
4. Only mitotic division takes place. 4. Meiosis and mitosis both take place.
5. No formation of sex organs. 5. Formation of sex organs is essential.
6. No evolutionary significance. 6. It introduces variation hence it is of evolutionary significance.

2. Vegetative reproduction is also considered a type of asexual reproduction because it does not involve meiotic division and there is no formation and fusion of gametes.

Question 3.
How does an encysted Amoeba reproduce on the return of favourable conditions? (CBSE Sample Paper 2019-20)
Answer:
Multiple fission in encysted Amoeba:

  • Amoeba withdraws pseudopodia and secretes a cyst wall around itself. This phenomenon is called encystation.
  • Amoeba divides by multiple fission.
  • It produces a large number of pseudo- conidiospores.
  • The cyst wall breakdown.
  • The spores are liberated and settle down on suitable substrates and grow as amoebae. This process is also called sporulation.

Question 4.
Discuss the advantages and disadvantages of asexual reproduction.
Answer:
Advantages of asexual reproduction:

  1. It involves simple mitotic division in single-parent and it may produce a large number of young ones.
  2. Young ones produced by asexual methods are genetically similar to the parent.
  3. It helps in the dispersal of offspring to far off places.

Disadvantages of asexual reproduction.

  1. The young ones thus produced do not possess much capacity to adapt rapidly to the environmental changes taking place in quick succession.
  2. No genetic recombination occurs thus no variation occurs.

Question 5.
Discuss the advantages and disadvantages of sexual reproduction.
Answer:
Advantages of sexual reproduction:

  1. Genetic recombination, interaction, etc. take place which causes variations in the offspring, thus also form raw materials for evolution.
  2. The offspring adapt more comfortably and quickly to the change in environmental conditions and have better chances of survival.

Disadvantages of sexual reproduction. Usually, two parents of opposite sexes are required (except in hermaphrodite).

Question 6.
List various methods of natural vegetative propagation. Give examples:
Answer:

  1. Vegetative propagation by stems, e.g.Grasses, Turmeric, Onion, Colocasia, Potato, Gladiolus and Crocus.
  2. Vegetative propagation by roots, e.g. Murraya sp., Albizzia Lebbac, Dalbergia sissoo, Tuberous roots of sweet potato, Asparagus, Tapioca, Dahlia and Yams (Dioscorea).
  3. Vegetative propagation from reproductive organs. Flower buds of century plant (Agave sp.) develop into bulbils.

Question 7.
Define external fertilisation. Mention its disadvantages:
Answer:
The fertilisation in which the fusion of gametes occurs outside the body of the female in an external medium, i.e. water, is called external fertilisation.

Examples. Bony fishes, amphibians, etc. Organisms that exhibit external fertilisation show great synchrony between the sexes in order to liberate the gametes at the same time.

Disadvantages of external fertilisation:

  1. A large number of gametes are produced to ensure fertilisation, thus there is wastage.
  2. The offspring formed are extremely vulnerable to predators, thus threatening their survival up to adulthood.

Question 8.
Explain the process of budding in yeast. (CBSE 2010)
Answer:
Budding in yeast. It is a common type of vegetative reproduction. In a medium which is abundantly supplied with sugar, yeast cytoplasm forms a bud-like outgrowth. The growth soon enlarges and a part of the nucleus protrudes into the bud and breaks off. The bud then begins to grow and then separates from the mother cell. Often it will itself form a bud before it breaks away, and straight or branched chains are produced.

Thus, as a result, branched or unbranched chains of cells called pseudo my cilium are produced. The cells are loosely held together. Sooner or later they become independent.

Question 9.
Describe the importance of vegetative propagation.
Answer:
Merits of vegetative propagation:

  1. Plants produced by vegetative propagation are genetically similar and constitute a uniform population called a clone.
  2. Plants with reduced power of sexual reproduction, long dormant period of seed, poor viability, etc. are multiplied by vegetative methods.
  3. Some fruit trees like banana and pineapple do not produce viable seeds. So these are propagated by only vegetative methods.
  4. It is a more rapid and easier method of propagation.
  5. Good characters are preserved by vegetative propagation.
  6. Some plants such as doob grass (Cynodon dactylon) which produce only a small quantity of seed are mostly propagated by vegetative propagation.
  7. Grafting helps in getting an economically important plant having useful characteristics of two different individuals in a short time.

Question 10.
Describe the post-fertilisation changes in a flower.
Answer:
Post-fertilisation changes in a flower.

Question 11.
Write a note on sexuality in plants.
Or
Coconut palm is monoecious while date palm is dioecious. Why are they called so?
Answer:
Sexuality in organisms: Sexual reproduction in organisms generally involves the coming together of gametes from two different individuals. But this is not always true.

Sexuality in Plants: Plants may have both male and female reproductive structures in the same plant (bisexual) or on different plants (unisexual). In several fungi and plants, terms such as homothallic and monoecious are used to denote the bisexual condition, and heterothallic and dioecious are used to describe the unisexual condition.

In flowering plants, the unisexual male flower is staminate, i.e. bearing stamens, while the female is pistillate or bearing pistils. In some flowering plants, both male and female flowers may be present on the same individual (monoecious) or on separate individuals (dioecious). Some examples of monoecious plants are cucurbits and coconuts and dioecious plants are papaya and date palm.

Very Important Figures:


1. Animals from colder climates generally have shorter limbs. This is called
(a) Allen’s rule
(b) Johnson’s rule
(c) Arber’s rule
(d) Niche rule

2. Niche is defined as
(a) a component of an ecosystem
(b) an ecologically adapted zone of a species
(c) the physical position and functional role of a species within the community
(d) all plants and animals living at the bottom of a water body.

3. It natality is balanced by mortality in a population at a given time, there will be a/an
(a) decrease in the population size
(b) increase in the population size
(c) zero population growth
(d) population explosion

4. Mycorrhiza is an example of
(a) ectoparasitism
(b) mutualism
(c) endoparasitism
(d) predation

5. The interspecific interaction in which one partner is benefitted and the other is unaffected (neutral), is called
(a) amensalism
(b) mutualism
(c) competition
(d) commensalism

6. Individuals of one kind, i.e., one species occupying a particular geographic area, at a given time form a/an
(a) community
(b) biome
(c) population
(d) deme

7. The formula of exponential population growth curve, is
(a) dN/dt = rN
(b) dt/dN rN
(c) dN/rN = dt
(d) rN/dN = dt

8. Niche overlap indicates
(a) mutualism between two species
(b) active cooperation between two species
(c) sharing of one or more resources between the two species
(d) two different parasites on the same host.

9. Amensalism is an association between two species where [NCERT Exemplar]
(a) one species is harmed and other is benefitted
(b) one species is harmed and other is unaffected
(c) one species is benefitted and other is unaffected
(d) both the species are harmed.

10. A population has more young individuals compared to the older individuals. What would be the status of the population after some years? ]NCERT Exemplar]
(a) It will decline
(b) It will stabilise
(c) It will increase
(d) It will first decline and then stabilise

11. Which of the following would necessarily decrease the density of a population in a given habitat? [NCERT Exemplar]
(a) Natality > mortality
(b) Immigration > emigration
(c) Mortality and emigration
(d) Natality and immigration

12. What parameters are used for tiger census in our country’s national parks and sanctuaries? [NCERT Exemplar]
(a) Pug marks only
(b) Pug marks and faecal pellets
(c) Faecal pellets only
(d) Actual head counts

13. The organisms which can tolerate and thrive in a wide range of temperature, are called _______ .

Answer/Explanation

Answer:
Explaination: Eury thermal

14. The salinity (measured in parts per thousand) in the sea is ______ .

Answer/Explanation

15. _______ is any attribute of an organism (morphological, physiological and behavioural) that enables it to live and reproduce in the given area. 24 Match the terms in Column I with their

Answer/Explanation

Answer:
Explaination: Adaptation

16. _______ refers to the number of births during a given period of time that are added to the initial density.

Answer/Explanation

Answer:
Explaination: Natality

17. In a logistic growth curve, the final phase is an _______ .

Answer/Explanation

Answer:
Explaination: Asymptote

18. _______ fish breed only once in their life time.

Answer/Explanation

Answer:
Explaination: Pacific salmon

19. An orchid growing as an epiphyte on a mango tree, is an example of _______ .

Answer/Explanation

Answer:
Explaination: Commensalism

20. _______ is an important process as it facilitates energy transfer through various organisms.

Answer/Explanation

Answer:
Explaination: Predation

21. _______ showed that five closely related species of warblers living on the same were able to avoid competitions and co-exist.

Answer/Explanation

Answer:
Explaination: MacArthur

22. Zooplanktons enter, a state of suspended development under unfavourable conditions.

Answer/Explanation

Answer:
Explaination: Diapause

23. Match the terms in Column 1 with those in Column II.

Column I Column II
A. Amensalism 1. The interspecific interaction, where both are equally benefitted.
B. Parasitism 2. The interspecific interaction, where one is benefitted and one is neutral.
C. Mutualism 3. The interspecific interaction, where one is harmed and the other is neutral.
D. Commen­salism 4. The interspecific interaction, where one is benefitted and one is harmed.
E. Competition
Answer/Explanation

Answer:
Explaination: A – 3, B – 4, C – 1, D – 2

24 Match the terms in Column I with their descriptions in Column II.

Column I Column II
A. Home­ostasis 1. Animal which can tolerate a wide range of temperature.
B. Confor­mers 2. The number of births in a given population at a given time.
C. Natality 3. Per capita births in a given population.
D. Eury- thermal 4. A Maintenance of a relatively constant internal environment.
5. Animals which change their body temperature according to the ambient temperature.
Answer/Explanation

Answer:
Explaination: A – 4, B – 5, C – 2, D – 1

25. Zooplanktons enter a state of suspended development, called diapause, under unfavourable conditions. [True/False]

Answer/Explanation

26. The success of mammals is due to their ability to change their body temperature according to their surroundings. [True/False]

Answer/Explanation

27. Small animals like shrews and humming birds are rarely found in polar regions. [True/False]

Answer/Explanation

28. Organisms living in water bodies (lake, sea, river) do not face any water related problems. [True/False]

Answer/Explanation

Answer:
Explaination: False.

29. dSfdt=rN is the equation describing logistic growth. [True/False]

Answer/Explanation

Answer:
Explaination: False.

Directions (Q30 to Q32): Mark the odd one in each of the following groups.
30. Aestivation, Migration, Hibernation, Diapause.

Answer/Explanation

Answer:
Explaination: Migration.

31. Parasitism, Predation, Commensalism, Amensalism.

Answer/Explanation

Answer:
Explaination: Amensalism.

32. Ticks, Lice, Copepods, Tapeworm.

Answer/Explanation

Answer:
Explaination: Tapeworm.

33. Who is considered as the ‘Father of Ecology ’ in India?

Answer/Explanation

Answer:
Explaination: Ramdeo Misra.

34. What is ecology at the organismic level?

Answer/Explanation

Answer:
Explaination: Ecology at the organismic level is essentially physiological ecology, which tries to understand how different organisms are adapted to their environments in terms of not only survival but also reproduction.

35. What causes the annual variation in the intensity and duration of temperature?

Answer/Explanation

Answer:
Explaination:
– Rotation of earth around the Sim.
– Tilt of the earth on its axis.

36. Name the two factors that cause the formation of major biomes.

Answer/Explanation

Answer:
Explaination:
– Variation in the intensity and duration of temperature.
– Variation in precipitation.

37. What does the ecological niche of an organism represent?

Answer/Explanation

Answer:
Explaination: Ecological niche of an organism represents the range of conditions it can tolerate, the resources it utilises and its functional role in the ecosystem.

38. Why are mango trees unable to grow in temperate climate? [AI 2016C]

Answer/Explanation

Answer:
Explaination:
– The levels of thermal tolerance of species determine their geographical distribution, because temperature affects the physiological functions by affecting the kinetics of enzymes.
– Stenothermal organisms (like mango) can tolerate and survive only in a narrow range of temperature, say tropics.

39. Mention the effect of global warming on the geographical distribution of stenothermals like amphibians. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Stenothermal animals have tolerance to a narrow range of temperatures and hence their geographical distribution would be much affected.

40. Between amphibians and birds, which will be able to cope with global warming? Give reason. [HOTS]

Answer/Explanation

Answer:
Explaination: Birds will be able to cope with global warming they are eurythermals and can tolerate a wide range of temperatures.

41. How do herbs and shrubs survive under the shadow of big canopied trees in forests?

Answer/Explanation

Answer:
Explaination: The herbs and shrubs growing in the forests are adapted to photosynthesise optimally under very low light conditions.

42. Name a ‘photoperiod’-dependent process, one each in plants and in animals. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:
– Flowering in plants.
– Timing of foraging or migration in plants.

43. Mention any two activities of animals which get cues from diurnal and seasonal variations in light intensity. [Delhi 2011C]

Answer/Explanation

Answer:
Explaination:
(i) Timing their foraging.
(ii) Migratory activities.
(iii) Reproduction. (any two)

44. Why are green algae not likely to be found in the deepest strata of the ocean? [AI 2013] [HOTS]
Or
Why are green plants not found beyond a certain depth in the ocean? [Delhi 2011] [HOTS]
Or
Why are green algae not found at lower depths of a sea? [Delhi 2011C]

Answer/Explanation

Answer:
Explaination: Green algae or plants are not found beyond a certain depth, as light (not all colour components of visible spectrum) is not available.

45. What is the advantage of homeostasis to organisms that exhibit it?

Answer/Explanation

Answer:
Explaination: Homeostasis enhances the overall fitness of organisms because all biochemical reactions and physiological functions proceed with maximal efficiency.

46. Which feature of mammals, is the success rate of them, attributed to?

Answer/Explanation

Answer:
Explaination: Their ability to maintain a constant body temperature irrespective of the environmental temperature.

47. Why have many animals not evolved thermo¬regulation? [HOTS]

Answer/Explanation

Answer:
Explaination: Thermoregulation is an energy-expensive phenomenon considering the cost and benefit, many animals have not evolved thermoregulation.

48. What are partial regulaters?

Answer/Explanation

Answer:
Explaination: Partial regulaters are those species which have the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.

49. What are osmoconformers?

Answer/Explanation

Answer:
Explaination: Osmoconformers are those organisms which regulate the osmolarity of their body fluids according to their surrounding medium.

Answer/Explanation

Answer:
Explaination: Migration refers to the movement of animals from the stressful habitat to a more hospitable area and return to the original place once the stressful period is over.

51. Name the National Park in India where migratory birds arrive in winter from Siberia.

Answer/Explanation

Answer:
Explaination: Keolado National Park, Bharatpur.

52. Mention how bears escape from stressful time in winter. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: Bears go into hibernation in winter.

53. How do snails escape from the stressful time in summer? [AI2013C]
Or
How do animals like fish and snails avoid summer-related unfavourable conditions? [Delhi 2010]

Answer/Explanation

Answer:
Explaination: Snails and fish go into aestivation in summer.

54. When and why do animals like frog/bear hibernate?

Answer/Explanation

Answer:
Explaination: If the unfavourable (stressful) conditions are for a short duration and if the animals are not able to migrate, they hibernate during extreme winter to avoid the stress by escaping in time.

55. When and why do animals like snails go into aestivation?

Answer/Explanation

Answer:
Explaination: When the snails are not able to migrate from the stressful conditions in the habitat, they undergo aestivation during hot summers to avoid stress by escaping in time.

56. Give an example of an organism that enters ‘diapause’ and why? [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
– Zooplankton.
– It is to tide over the temporary unfavourable conditions in the habitat.

57. How do seed-bearing plants tide over dry and hot weather conditions? [AI 2013C]

Answer/Explanation

Answer:
Explaination: In seed-bearing plants, the seeds and other vegetative reproductive structures serve to tide over the unfavourable conditions they germinate to form new plants under favourable conditions.

Answer/Explanation

Answer:
Explaination: Adaptation is defined as any morphological, physiological or behavioural attribute of an organism that enables it to survive and reproduce in its habitat.

59. How do spines help the cactus plants survive in the desert?

Answer/Explanation

Answer:
Explaination:
(i) Leaves are reduced to spines to check transpiration.
(ii) Spines keep away the browsing animals.

60. What is meant by Allen’s Rule?

Answer/Explanation

Answer:
Explaination: Allen’s rule refers to the reduction of heat loss in animals by having shorter ears and limbs.

61. Why is population ecology considered an important area of ecology?

Answer/Explanation

Answer:
Explaination: Population ecology is an important area of ecology, because it links ecology with population genetics and evolution natural selection operates at the level of population.

62. If 8 individuals in a laboratory population of 80 fruit flies died in a week, then what would be the death rate of the population for the said period? [Delhi 2010]

Answer/Explanation

Answer:
Explaination: The death rate of fruit flies is 8/80, i.e. 100 per thousand or 10 per cent or 0.1 per individual.

63. In a pond, there were 20 Hydrilla plants. Through reproduction, 10 new Hydrilla plants were added in a year. Calculate the birth rate of the population. [Delhi 2010]

Answer/Explanation

Answer:
Explaination: The birth rate of Hydrilla is 10/20, i.e. 500 per thousand or 50 per cent or 0.5 per individual.

64. Define population density.

Answer/Explanation

Answer:
Explaination: Population density refers to the total number of individuals of a species present per unit area or volume at a given time.

65. Provide an instance where the population size of a species can be estimated indirectly, without actually counting them or seeing them. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Tiger census is carried out by counting the pug marks or faecal pellets.

Answer/Explanation

Answer:
Explaination: Natality is defined as the number of births that are added to the initial density in a population during a given period of time.

Answer/Explanation

Answer:
Explaination: Mortality refers to the number of deaths in the population during a given period.

68. What does nature’s carrying capacity for a species indicate? [Foreign 2016]

Answer/Explanation

Answer:
Explaination: It refers to the maximum number of individuals of a population that the given environment can sustain with its resources.

69. Name two organisms (one plant and one animal) which breed only once in their lifetime.

Answer/Explanation

Answer:
Explaination: Bamboo Pacific Salmon Fish.

70. Why have life history variations evolved?

Answer/Explanation

Answer:
Explaination: Life history variations have evolved in organisms to maximise their reproductive fitness or Darwinian fitness in their natural habitats.

71. Mention any two reasons why plants depend on other organisms for their survival, even though they make their own organic food.

Answer/Explanation

Answer:
Explaination:
(i) Plants depend on animals (mainly insects) for pollination.
(ii) They also depend on animals for dispersal of seeds and/or fruits.
(iii) They depend on the soil microbes, which can carry out decomposition of organic matter and return the inorganic nutrients to the soil for absorption by plants. (any two)

72. Why are cattle and goats not browsing the Calotropis growing in the fields? [Foreign 2011]

Answer/Explanation

Answer:
Explaination: Calotropis plants produce highly toxic cardiac glycosides hence, the cattle avoid browsing them.

73. Write one common feature among predation, parasitism and commensalism.

Answer/Explanation

Answer:
Explaination: In all these, the interacting species live closely together and one of the species is benefitted.

74. What term is given to the predators of plants.

Answer/Explanation

Answer:
Explaination: Herbivores.

75. What type of interaction is shown by a sparrow eating the seeds?

Answer/Explanation

Answer:
Explaination: Predation.

76. An exotic variety of prickly pear introduced into Australia turned out to be invasive. How was it brought under control? [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: By introducing a cactus-feeding moth.

77. Why are predators ‘prudent’ in nature? [HOTS]

Answer/Explanation

Answer:
Explaination: Predators are prudent in nature because if a predator is too efficient and over-exploits its prey, then the prey might become extinct and following it, the predator will also become extinct.

78. Why do predators avoid eating monarch butterfly? How does the butterfly develop this protective feature? [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
– The monarch butterfly is highly distasteful to the predators.
– It is due to a chemical present in its body the butterfly acquires this chemical during its caterpillar stage, by feeding on a poisonous weed.

79. Write what the phytophagous insects feed on. [Delhi 2012]

Answer/Explanation

Answer:
Explaination: Phytophagous insects feed on the sap and other parts of the plants.

80. Why is the problem of predation in plants more severe than that in animals? [HOTS]

Answer/Explanation

Answer:
Explaination: Problem of predation is severe for plants because they cannot move away from their predators.

We hope the given Biology MCQs for Class 12 with Answers Chapter 13 Organisms and Populations will help you. If you have any query regarding CBSE Class 12 Biology Organisms and Populations MCQs Pdf, drop a comment below and we will get back to you at the earliest.


Fibre to Fabric Class 6 Extra Questions Science Chapter 3

NCERT Extra Questions for Class 6 Science Chapter 3 Fibre to Fabric

Variety in fabrics

Question 1.
What is fabric?
Answer:
Fabric means a woven material, a textile or other material resembling woven cloth. Fabric is made up of yarns. Fabrics are made by the two main processes known as weaving and knitting.

Question 2.
On what factors does our type of clothing depend?
Answer:
Type of clothing which we wear is influenced by climate, occupation, culture and daily needs.

Question 3.
Why are cotton and woollen clothes rough and silk, rayon, nylon, polyester smooth to touch?
Answer:
Roughness of cotton and woollen fibre is due to presence of many folds and uneven surfaces in it. Silk, rayon, nylon and polyester are smooth because they have long plain, fine structure.

Question 1.
Classify the following fibres into natural and man-made: cotton, nylon, jute, wool, silk, rayon, polyester.
Answer:

Question 2.
From where wool is obtained?
Answer:
Wool is obtained from the fleece of sheep or goat.

Question 3.
What is known as golden fibre?
Answer:
Jute is the cheapest natural fibre and is known as the golden fibre.

Question 4.
When we burn wool, why do we get the smell of hair bum?
Answer:
Wool is obtained from the fleece (hair) of sheep, goat, yak, etc. This is the reason why burning of wool gives smell like burning of hair.

Some plant fibres

Question 1.
Name the plant from which jute is obtained. From which of its part do we get jute?
Answer:
Jute is obtained from ‘Putson’. It is obtained from its stem.

Question 2.
Which parts of these plants have fibres?

Question 3.
Name the country which invented cotton clothing.
Answer:
India.

Question 4.
In which states of India, cotton is grown?
Answer:
Cotton is grown in Maharashtra, Gujarat, Punjab, Rajasthan, Tamil Nadu and Madhya Pradesh.

Question 5.
In which states of India, jute is cultivated?
Answer:
West Bengal, Bihar and Assam are the main producers of jute in India.

Question 6.
Which method is used to harvest cotton from the plants?
Answer:
Hand picking.

Question 7.
What is ginning?
Answer:
Ginning is the process of separating cotton fibres from its seeds.

Question 8.
What are bales?
Answer:
Raw cotton fibres are compressed into bundles of approximately 200 kg. These compressed cotton bundles are called bales.

Question 9.
Which type of soil is the best for the cultivation of cotton?
Answer:
Black soil.

Question 10.
Which type of soil is best suited for jute crop?
Answer:
Alluvial soil in the delta regions of rivers like the Ganga and the Brahmaputra are the best for the cultivation of jute.

Question 11.
In which season, jute (putson) is cultivated?
Answer:
Rainy season.

Question 12.
What are the uses of cotton?
Answer:
Cotton has a variety of uses. Some uses of cotton are given below:

  • Cotton or cotton in combination with other fibres is used in manufacture of textiles.
  • Cleaned cotton is used as an absorbent in hospitals.
  • Unspun cotton is used ,as fillers in mattresses, pillows and quilts.
  • Cotton is used as a main raw material in manufacturing of rayon and in paper industry.
  • Due to high water absorption property, clothes made from cotton are extensively used as mops in household and for cleaning machines in industries.

Question 13.
Explain various steps in the manufacture of cotton fabric from cotton.
Answer:
Important steps in the manufacture of cotton fibres are as described below:

  1. Cotton is hand picked from the plants.
  2. Ginning: The picked cotton is taken to godowns where the seeds are pulled out of the cotton by steel combs.
  3. Bailing: Ginned cotton is compressed tightly into bundles weighing approximately 200 kg called bales.
  4. Raw cotton from bales is cleaned from straw and dried leaves, combed and straightened and finally converted into rope like strand called sliver.
  5. Spinning: To make this strand into yam strong enough for wearing, it is pulled and twisted.
  6. Yarn is wound on big reels called ‘bobbins’. These bobbins of yam are subjected to weave for making cloth.
  7. Weaving: Weaving from yam is done in the looms.
  8. Bleaching and dyeing: Fabric made in the loom is grey in colour. The fabric is now bleached and dyed at a finishing plant.

Question 14.
In which season is cotton planted? What is its course of growth?
Answer:
It is planted early in the spring. Cotton plants grow steadily and soon become bushes of 3 to 6 feet high. After about 2 months, they bear white or yellowish flowers which turn pink or red after a few days. The petals of the flowers fall, leaving behind tiny green seeds. This later grows into spherical-shaped structure of the size of a walnut, which is called cotton boll. As the cotton bolls grow steadily, the seeds and the fibres grow inside. On maturing, the green bolls begin to turn brown. On complete maturation, they become ready to burst open, exposing the white fibres. As the fibres dry in the sun, they become fluffy.

Question 15.
Why are jute plants cut at flowering stage and not on complete maturation?
Answer:
Jute plants are cut at the time of flowering stage because a good quality of fibre is obtained at this stage. On complete maturation of plant, fibres of its stem become very hard.

Question 16.
What are the important uses of jute?
Answer:

  • Jute is extensively used for making gunny bags, potato sacks, carpets, curtains, coarse clothes and ropes, etc.
  • These days, fine quality of jute is also used for making jute fabrics.

Question 17.
What is retting? Explain how fibres are obtained from the jute plants.
Answer:
Jute plants are cut at the flowering stage when plants are 8-10 feet high. The cut plants are grouped at different places in the field for a few days when most of the leaves dry up and fall down. The plants are now tied into small bundles. The bundles are made to sink in stagnant water of a pond for a few days and then the gummy skin rots out to separate fibres. This process is called ‘retting’. Fibre is extracted from the retted jute by hand, with jerks and pulls. The.dried fibres are then tied together in small bundles.

Spinning cotton yarn

Question 1.
What is spinning?
Answer:
The process of making yam from fibres is called spinning.

Question 2.
Name two simple devices used for spinning.
Answer:

Question 3.
Name the person who made the charkha popular during independence movement.
Answer:
Mahatma Gandhi

Question 4.
Where were the cotton and flax plants cultivated in ancient Egypt?
Answer:
Cotton and flax plants were cultivated near the river Nile in ancient Egypt.

Question 5.
How are natural fibres better than synthetic fibres?
Answer:
The natural fibres absorb sweat, give cooling effect and comfort in all seasons.

Activity 4.
Hold some cotton wool in one hand. Pinch some cotton between the thumb and forefinger of the other hand. Now, gently start pulling out the cotton, while continuously twisting the fibres (See Fig. 3.2 on page 31). Are you able to make a yam?

Yes, the cotton fibres are drawn out and twisted into long thread like strands. These strands are spun with the help of spinning machines to yam.

Yarn to fabric

Question 1.
What is weaving?
Answer:
The process of arranging two sets of yam together to make a fabric is called weaving.

Question 2.
What is knitting?
Answer:
In knitting, a single yam is used to make a piece of fabric.

Question 3.
What are looms?
Answer:
Loom is a device on which weaving of fibres is done.

Question 4.
Name the two types of looms.
Answer:
Looms are of two types:

History of clothing material

Question 1.
What were the wearings of the people of stone age?
Answer:
During the stone age, people wore bark, big leaves of trees or animal skins to keep themselves warm. ‘

Question 2.
Why primitive life was confined to the tropics? When was it possible for the people to migrate to colder regions?
Answer:
Primitive men and women had no idea about clothes, and were at the mercy of their environment. Primitive life was confined mostly to the tropics where the climate was warm and no clothing was needed. Only after the invention of fire, it became possible for people to migrate to colder regions.

Question 3.
What are the three stages in history of the development of clothing material? t
Answer:
In terms of raw materials, cloth making was developed in three stages. The first stage was cloth from plant fibres, such as flax, cotton, nettles and inner bark of the trees. The second stage began with the use of animal fibres especially wool and silk. Silk came to various parts of the world from China. The third stage in the history of clothing began in the late 19th century with the development of man-made or synthetic fibres like rayon, nylon and polyester. Now man-made fibres combined with other animal with or without plant fibres are used for making clothes for improved strength, wearing ability and other qualities.

Question 4.
When stitching was not known, how did people use fabrics available with them?
Answer:
When stitching was not known, people simply draped the fabrics around different parts of their body. Many different ways of draping fabrics were used.

Question 5.
Name the clothes which are used as an unstitched piece of fabric even now.
Answer:
Saree, dhoti, lungi or turban are the clothes which are used as an unstitched piece of fabric even now.

Objective Type Questions

Question 1.
Match the following items given in Column A with that in Column B

Column A Column B
(a) Jute is obtained from (i) Charkha
(b) Fibre from retted jute are extracted by (ii) Sliver
(c) Separation of fibres from jute stem (iii) Bales
(d) Compressed bundles of cotton (iv) Retting
(e) Cotton is collected from cotton plants by (v) Hand picking
(f) Separation of cotton from seeds (vi) Silk and wool
(g)Loose rope of cotton fibres (vii) Stem of‘putson’
(h) Animal fibres (viii) Hands with jerks and pulls
(i)Suitable for wearing in kitchen (ix)Ginning
(j) Used to spin yams (x) Cotton clothes

Column A Column B
(a) Jute is obtained from (vii) Stem of ‘putson’
(b) Fibre from retted jute is extracted by (viii) Hands with jerks and pulls
(c) Separation of fibres from jute stem (iv) Retting
(d) Compressed bundles of cotton (iii) Bales
(e) Cotton is collected from cotton plants by (v) Hand picking
(f) Separation of cotton from seeds (ix) Ginning
(g) Loose rope of cotton fibres (ii) Sliver
(h) Animal fibres (vi) Silk and wool
(i) Suitable for wearing in kitchen (x ) Cotton clothes
(j) Used to spin yams (i) Charkha

Question 2.
Fill in the blanks with appropriate words:

  1. Clothes are made up of …………… .
  2. Different clothing materials have ………………. properties.
  3. Cotton plants need…………………. climate.
  4. Cotton is planted in the ………….. .
  5. …………… soil is excellent for the cultivation of cotton.
  6. …………………….. Usually cotton is picked from the plants.
  7. Separation of cotton fibres from their seeds is called …………….. .
  8. A ………………. of cotton is a loose strand of cotton fibres.
  9. In villages, the cloth is woven on small scale in …………… .
  10. Jute is cultivated in ……………… season.
  11. Jute is grown in …………………. soil.
  12. On large scale, cotton clothes are made by machines in ……………. .
  13. Twisting of fibres into yarn increases the ………………. of fibres.
  14. Cotton fibres are obtained from the …………….. of cotton plant.
  15. Jute fibre is obtained from the …………………. of jute plant.
  16. Tightly compressed bundles of cotton are called ……………. .
  17. The process of getting fibres from the jute stem is called …………… .
  18. People migrated to colder regions only after the invention of …………… .
  1. fibres
  2. different
  3. warm
  4. spring
  5. Black
  6. hand
  7. ginning
  8. sliver
  9. handloom
  10. rainy
  11. alluvial
  12. powerloom
  13. cohesion and strength
  14. seeds
  15. stem
  16. bales
  17. retting
  18. fire

Question 3.
State whether the statements given below are True or False:

  1. Ml the plants have fibres in their body structure.
  2. Cotton is the most important industrial crop.
  3. India was the proud inventor of cotton clothing.
  4. Cotton plants need cold climate.
  5. Alluvial soil is best suited for cotton.
  6. Jute is obtained from the stem of ‘putson’.
  7. Jute fibres are quite strong, 6-8 feet long and have a silky lusture.
  8. Primitive men and women had no idea about clothes.
  9. Type of clothing which we wear is influenced by climate, occupation, culture and daily needs.
  10. Cotton and woollen clothes are smooth to touch.
  11. Clothes are made from threads, and threads, in turn, are spun from fibres, (xii) Coconut fibres are good for making yarn.
  12. Twisting of fibres into yam increases cohesion. ‘
  13. While working in kitchen, we should wear cotton clothes.
  14. Clothes protect us from adverse weather condition.
  1. True
  2. True
  3. True
  4. False
  5. False
  6. True
  7. True
  8. True
  9. True
  10. False
  11. True
  12. False
  13. True
  14. True
  15. True

Question 4.
Choose the correct option in the following questions:

(i) Which one of the following is a synthetic fibre?
(a) Nylon
(b) Rayon
(c) Polyester
(d) All of these
Answer:
(d) All of these fibres are man-made.

(ii) Which is a natural fibre?
(a) Silk
(b) Nylon
(c) Rayon
(d) All of these
Answer:
(a) Only silk is natural.

(iii) The clothes are made up of thinner and thinner strands called
(a) yam
(b) thread
(c) fibre
(d) fabric
Answer:
(c) Fibre is thinnest unit of fabric.

(iv) Separation of fibres of cotton from its seeds is known as
(a) weaving
(b) spinning
(c) knitting
(d) ginning
Answer:
(d) Cotton fibres are separated from seeds by combing and the process is called -¬ginning.

(v) Jute fibres are obtaine from
(a) stem of jute plant
(b) seeds of jute plant
(c) fruit covering of jute plant
(d) roots of jute plant
Answer:
(a) Jute fibres are obtained from the stem of jute plant.

(vi) Number of yams used to make fabric by weaving and knitting are
(a) two sets of yams in each case
(b) single yam in each case
(c) two sets of yams in weaving and single in knitting
(d) single yam in weaving and two sets in knitting
Answer:
(c) In weaving two sets of yam are arranged while knitting is done by a single yam.

(vii) Weaving of fabric is done in
(a) handlooms
(b) power looms
(c) both (a) and (b)
(d) takli
Answer:
(c) Weaving is done both in handlooms and power looms.

(viii) Which one is spinning device?
(a) Takli
(b) Loom
(c) Charkha
(d) Both (a) and (c)
Answer:
(d) In looms, fabric is woven while by takli and charkha, yam is made.

(ix) Which of the following is a plant fibre?
(a) Wool
(6) Silk
(c) Cotton
(d) Nylon
Answer:
(c) Cotton is a plant fibre.

(x) The right time to cut jute plants is
(a) matured stage
(b) before flowering stage
(c) flowering stage
(d) any time after flowering
Answer:
(c) Jute plants are usually cut at the flowering stage.


Materials and Methods

The 10 studies are (A) a population of 31 recombinant inbred lines of Arabidopsis thaliana (Paul-Victor et al. 2010) (B) nine European sand-dune annual species (Turnbull et al. 2008a) (C) five European monocarpic species (A. Goodenough, unpublished data) (D) seven European monocarpic species (Rose et al. 2009) (E) nine west Asian annual grass species (J. Cunniff, unpublished data) (F) eight European grass species including five perennials (J. Houghton, unpublished data) (G) nine European perennial grass species (Hautier et al. 2010) (H) 21 C3 and C4 grass species including 18 perennials (Taylor et al. 2010) (I) eight European herbaceous perennial species (Y. Hautier, unpublished data) (J) six Bornean tree species from the family Dipterocarpaceae (P. Saner, unpublished data see Plate 1). For more details of all studies, see Appendix A. For the two monocarpic perennial data sets, there was complete overlap among species however, they are independent experiments carried out at different times. For the four grass data sets, there was very little species overlap (only one species, Dactylis glomerata occurs in two data sets). Seed mass data was taken from the original studies and more details are provided in Appendix A. The data sets were grouped in three different ways: (1) by life form (forbs, grasses, trees), (2) by co-occurrence (whether or not the species represent a pool of naturally co-occurring species), (3) by life span (whether the species are short or long lived). The typical life span of established plants in the short-lived category is less than 3–5 years this group consists of annuals and short-lived monocarpic perennials in the long-lived category, typical life span of established plants is often greater than five years this group consists of perennial grasses, forbs, and trees. We used all studies for the life-form analysis, but only included the five perennial species from study F and the 18 perennial species from study H in order to have no studies with multiple life-form categories. Plants were usually started from seed (except study J where seedlings were used) and repeatedly measured (study D) or repeatedly harvested (all others). The experiments often incorporated additional treatments, e.g., high/medium/low light or different pot sizes. In this case, parameters are presented from one treatment only, always the one with the highest growth rate, e.g., the highest light level or the largest pot size.

Dipterocarp seedlings growing in a shadehouse in Malaysian Borneo (Study J). Photo credit: C. D. Phillipson.

Growth rate calculations

Conventional RGR was calculated using either the average size of all individuals at the first and last available harvests (Eq. 1) or the slope of a linear regression between ln(size) and time. For comparison, we calculated SGR by fitting growth curves to plots of size vs. time and calculating SGR at a common reference size (Mc) in this case, the average size of all plants halfway through the study (see also Rose et al. 2009, Hautier et al. 2010, Paul-Victor et al. 2010, Taylor et al. 2010, Paine et al. 2011). Calculating SGR involves fitting a growth curve using non-linear regression for each species to a plot of plant size (usually mass) vs. time. SGR can be calculated at any size or simply plotted as a function of size however, we used the average size halfway through the experiment to get a value of SGR that is comparable to conventional RGR (which is also an average). The reference size obviously differs among studies, in keeping with the range of life forms represented. Another advantage of choosing the average size halfway through each study is that, within a given study, all species occurred at the reference size during the lifetime of the experiments. Thus, we can calculate, for each species, the growth rate at Mc without extrapolating beyond the range of sizes observed for any species.

Fitting growth curves

Because of the nature of the data, we fitted different functional forms to different data sets. For all studies except one (sand-dune annuals, see Appendix B) we fitted growth curves in R (R Core Development Team 2011) using either nonlinear mixed-effects models where models required both fixed and random effects (nlme) or nonlinear standard regression models where no random effect was required (gnls). When repeated measures were made on individuals, plant identity was included as the random effect (see Pinheiro and Bates 2000 for a description). In total, we used four different growth functions, as appropriate for the different growth trajectories: power-law, asymptotic regression, asymptotic regression with an offset (von Bertalanffy), and the four-parameter logistic. The choice of curve was determined by the nature of the data, in particular whether there was an indication of an asymptote, and refined by examining plots of residuals. All models were fitted with the help of a self-starting routine (with the exception of the power-law function) and following the general guidance laid out in Pinheiro and Bates (2000). For more detailed guidance on choosing a suitable growth curve and the mechanics of fitting such models see Paine et al. (2011). We illustrate the general method using power-law growth for other growth functions see Appendix B.

Power-law growth

Comparison of RGR and SGR

Once we had values of both RGR and SGR for each species, we carried out an analysis of covariance and a mixed-effects model analysis (Pinheiro and Bates 2000) on the log-transformed growth rates. We used both types of analysis because statistical inference is simpler for analysis of covariance (Bolker et al. 2009), but this analysis does not allow us to partition the variance in slopes due to the grouping variables (e.g., life form, co-occurrence, and life span). Average slopes were calculated from the analysis of covariance model using contrasts. We carried out Spearman rank correlations on SGR and RGR values obtained from each study to see whether or not the rankings of species with respect to growth rate is affected by the choice of growth rate methodology.


Monocots versus Dicots

In 1682, John Ray published his Methodus Plantarum Nova, in which Dicotyledones and Monocotyledones were first given formal taxonomic standing. This system was popularized by the French botanist Antoine Laurent de Jussieu in his Genera Plantarum of 1789, a work which improved upon, and gradually replaced, the system of plant classification devised by Linnaeus.

The fuzzy distinction between the classes.

Even after the general acceptance of Monocots and Dicots as the primary groups of flowering plants, botanists did not always agree upon the placement of families into one or the other class. Even in this century some plants called paleoherbs have left problems for taxonomy of angiosperms. These plants have a mix of characters which do not occur together in most other flowering plants. For instance, the Nymphaeales, or water lilies, have reticulate venation in their leaves, and what may be a single cotyledon in the embryo. It is not clear whether it is a single lobed cotyledon, or two which have been fused. The water lilies also have a vascular arrangement in their stem similar to that of monocots.

There are also monocots which posses characters more typical of dicots. The Dioscoreales and Smilacaceae have broad reticulate-veined leaves the Alismataceae have acropetal leaf development and Potamogeton is one of several monocots to have floral parts in multiples of four.

This "fuzziness" in the definitions of Monocotyledonae and Dicotyledonae is not simply the result of poor botany. Rather, it is a real phenomenon resulting from the shared ancestry of the two groups. It is now believed that some of the dicots are more closely related to monocots than to the other dicots, and that the angiosperms do not all fit neatly into two clades. In other words, the dicots include a basal paraphyletic group from which the monocots evolved. Click here for a cladogram which illustrates our current understanding of basal angiosperm relations.

The characters which distinguish the classes.

Despite the problems in recognizing basal angiosperm taxa, the standard distinctions between dicots and monocots are still quite useful. It must be pointed out, however, that there are many exceptions to these characters in both groups, and that no single character in the list below will infallibly identify a flowering plant as a monocot or dicot.

The table summarizes the major morphological differences between monocots and dicots each character is dicussed in more detail below. For more information, refer to the page on monocot morphology.

Common questions about the classes.

Having taught in introductory botany for more than five years, I have fielded many questions from students, and present below some of the more common questions and misconceptions. Thanks go to my students for taking an active role in their own education, and asking these questions

Q: Are pine trees monocots or dicots?

A: Pines are conifers, and are neither monocots nor dicots. Only flowering plants are considered to be members of these two classes. This question is similar to asking whether a chicken is a monocot or a dicot it is neither.

Q: Do all dicots produce flowers?

A: Yes, sort of. All dicots and monocots are flowering plants, and so are descended from flower-producing plants. However, the flowers are not always large and showy the way we expect flowers to be. Oaks, maples, and sycamore are all dicot trees, but they do not produce obvious flowers. Grasses and cattails are monocots whose flowers are often overlooked because they do not have sepals or petals.

There are also some flowering plants which flower only rarely. Duckweeds are tiny flowering plants which reproduce and spread primarily by vegetative growth they grow by cellular division, and the resulting cluster will then break apart.

Q: If monocots don't have wood, then what supports palm trees?

A: Palms rely on overlapping leaf bases, thickened enlarged cells, and prop roots to stay up. This strategy is also used by cycads and tree ferns. We hope to have a special exhibit soon expanding on the architecture of trees which will explain this in more detail.


Welcome

The species is extremely dioeciously, with male and female flowers on the different plants. It is a small deciduous tree, typically growing to the 8-15 m tall. This fruit, syncope of achene, is roughly spherical, but very bumpy, and 7-15 cm in the diameter and it is filled with a sticky white sap. Fall color is a bright yellow-green with a lovely faint orange odor.

Aggregate fruit meaning

Aggregate means collection of small fruits. A fruit that contains a number of small fruits (fruitlets) is called an aggregate fruit. Fruitlets that are derived from a single flower are collectively called as etaerio. An aggregate fruit develops from the apocarpous ovary of a flower. The flower has multiple carpels which are not joined together and thus forms individual fruitlets on the same receptacle.

Aggregate fruit examples

Raspberry
Blackberry
Strawberry
Custard apple

Gluten

Gluten is a protein found in wheat, barley, rye and oats that can cause intestinal permeability (i.e. leaky gut). “The problem with gluten is that no human can digest it. It’s impossible to digest the gluten proteins that are in wheat, barley and rye,” certified chiropractic nutritionist Tom O’Bryan, author of “The Autoimmune Fix.” explained on a Bulletproof Radio podcast episode.

The spectrum of reaction to indigestibility of gluten places people into two categories: celiac or non-celiac gluten sensitivity, most of the population being the latter. Indigestible substances in the digestive system cause an immune response, immune responses take the form of inflammation. Inflammation is, more times than not, the culprit behind our brain fog, digestive discomfort and suboptimal nutrient absorption.

Gluten-containing grains break down in the gut into opioid compounds called gluteomorphins that trigger the same brain receptors as opiate drugs like heroin — meaning, they’re highly addictive.

Structurally, gluten is made up of two types of storage proteins, prolamins and glutelins. [3] Wheat-based glutelins are called glutenins, which consist of high molecular weight (HMW) and low molecular weight (LMW) subunits. Wheat products made with higher levels of HMW tend to be more elastic and subsequently more chewy (pizza dough or pretzels) whereas lower levels of HMW tend to take the form of pastries. [4] Originally, giladin (the wheat based prolamin) was thought to be the main antinutrient contributor to gluten, but its been shown that glutenin is equally as toxic. [5] So just because you are eating something that feels lighter, you are still downgrading your digestive system when you eat any form of gluten.

Gluten is hidden in places beyond the obvious sources products like soy sauce, beer and even processed meats contain gluten that may be downgrading your performance.


Bio 112 chapter 13 Quiz/Multiple choice study test

Green beetles are more visible to birds than brown beetles, so birdseed more green beetles.

Brown beetles survive to reproduce more often than green beetles do. The brown allele increases in frequency.

Pesticide is applied to a population of insects

Some insects have a gene that makes them resistant to the pesticide. these insects survive. insects without the gene die.

The surviving insects reproduce. the frequency of the resistant insects in the population increases.

A.More than one-half of the initial population died during the drought.
B. Finches with larger beaks had a survival advantage in the 1977 drought.
C. The most common beak size of the initial population was 8.8 millimeters. A very small proportion (

5%) of the initial population with this beak size survived.
D. The most common beak size of the surviving population was 10.3 millimeters. A very small proportion (

How many different genotypes are in this rabbit population?

How many different phenotypes are in this rabbit population?

How many different fur color alleles are in this rabbit population?

What is the allele frequency for the F allele in this population's gene pool?


A new holistic framework for the evolution of flower form

It is not surprising that plant reproductive ecologists have, until recently, had a narrow view of floral evolution, focusing almost exclusively on the process of pollination. Pollination is, after all, an event unique to flowers and one that defines the flowering plants or angiosperms as a group. But focusing narrowly on sexual functions of flowers and on the role of pollinators in mediating sexual reproduction has two shortcomings. This focus overlooks both other important functions of floral organs and the physiological integration of flowers with the vegetative body of the plant.

Scientists studying the functional ecology of plant secondary chemistry came to a similar juncture 20 years ago, when the diversity of secondary chemicals was viewed only in relation to herbivore pressure (apparency theory Feeny 1976, Rhoades and Cates 1976). Plant secondary chemistry was thought to reflect the ease with which plants could be found by herbivorous insects. Variation among habitats in the availability of resources such as carbon or nitrogen, which are the building blocks of secondary defenses, was ignored. Apparency theory nicely predicts interspecific variation in secondary chemistry in some plant communities but falls short of explaining patterns in others ( Howe and Westley 1988). A sea change in that discipline occurred when Coley (1983) and Coley et al. (1985) published papers that emphasized theoretical and empirical connections between plant secondary chemistry and resource availability. In showing how plant defenses might evolve in relation to underlying resources as well as herbivore pressure, Coley's work provided a powerful springboard for understanding plant chemical diversification. Similarly, our understanding of floral evolution can benefit from a more holistic approach to flower function that incorporates not only plant-pollinator relationships but also resource requirements for flower development and maintenance.

Clearly, hypotheses about the functional significance of floral variation are not mutually exclusive as illuminated by studies of P. viscosum, multiple ecological forces may act on flowers simultaneously. Pollinators, enemies, and resource heterogeneity appear to operate simultaneously in exerting selection on flower size and shape in this system and in at least one other system that has received comparable long-term study (I. aggregata Brody 1992, Campbell 1997). Recently, O'Connell and Johnston (1998) also reported that the magnitude of selection on flower size from insect pollinators varies markedly among microhabitats in a population of the pink lady's slipper orchid, Cypripedium acaule. Although still few in number, these examples point to the need for a more pluralistic view of natural selection on floral traits.

There are promising signs that plant reproductive ecologists are embracing broader new perspectives: Recently, an issue of Ecology spotlighted connections between pollination and herbivory ( Strauss and Armbruster 1997). Such studies may provide an ideal arena for addressing the resource-cost hypothesis because herbivores, by selectively reducing leaf area, essentially create resource (photosynthate) heterogeneity within plant populations. The abiotic environment is also gaining recognition as a source of selection on reproductive traits. For example, studies on the correlated evolution of physiological and reproductive characters are bringing new light to bear on the evolution of gender differences, no small part of which involves changes in flower morphology ( Laporte and Delph 1996, Dawson et al. 1998, Dawson and Geber 1999).

In this article, I have suggested that resource availability may influence the efficacy of pollinator-mediated selection in bringing about increases in flower size. An alternative and little-explored way in which the abiotic environment may affect the evolution of flower size or shape is as a force of natural selection on the developmental processes that underlie the growth and differentiation of flowers. For example, small flowers may reflect a history of selection for abbreviated development time under growing seasons characterized by rapidly deteriorating environmental conditions (Geurrant 1989, Eck-hart et al. 1998, Runions and Geber 1998). By resolving how abiotic stress, as a source of selection on developmental processes, affects the evolution of flower shape and size, such new research may illuminate not only why, but how, flowers come to vary.