Biology

Organisms and Populations

Question:

Why are coral reefs not found in the regions from. West Bengal to Andhra Pradesh but are found in Tamil Nadu and on the east coast of India?

Answer:

High salinity, optimal temperature and less siltation are essential to colonise corals. If siltation and fresh water inflow are very high, the corals don't colonise. In contrast when the siltation and fresh water inflow by the rivers are very less, the coral do colonise.

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Organisms and Populations

Q 1.

Does light factor affect the distribution of organisms? Write a brief note giving suitable examples of either plants or animals.

Q 2.

Why do all the fresh water organisms have contractile vacuoles whereas , majority of marine organisms lack them?

Q 3.

What is homeostasis?

Q 4.

What is the interaction between two species called?

Q 5.

List any four characters that are employed in human population census.

Q 6.

What is Mycorrhiza?

Q 7.

Lianas are vascular plants rooted in the ground and maintain erectness of their stem by making use of other trees for support. They do not maintain direct relation with those trees. Discuss the type of association the lianas have with the trees.

Q 8.

Define the following terms and give one example for each:
(a)Commensalism (b)Parasitism
(c)Camouflage (d)Mutualism
(e)Interspecific competition

Q 9.

In a sea shore, the benthic animals live in sandy, muddy and rocky substrata
and accordingly developed the following adaptations.
a. Burrowing  
b. Building cubes
c. Holdfasts/peduncle
Find the suitable substratum against each adaptation.

Q 10.

What is a tree line?

Q 11.

What would be the growth rate pattern, when the resources are unlimited?

Q 12.

Give an example for:
(a)An endothermic animal
(b)An ectothermic animal
(c)An organism of benthic zone

Q 13.

Comment on the following figures 1, 2 and 3:
A, B, C, D, G, P, Q, R, S are species
ncert-exemplar-problems-class-12-biology-organisms-and-populations-10

Q 14.

Which element is responsible for causing soil salinity? At what concentration does the soil become saline?

Q 15.

What is commensalism?

Q 16.

Species that can tolerate narrow range of temperature are called

Q 17.

What is brood parasitism? Explain with the help of an example.

Q 18.

In an aquarium two herbivorous species of fish are living together and feeding on phytoplanktons. As per the Gause's Principle, one of the species is to be eliminated in due course of time, but both are surviving well in the aquarium. Give possible reasons.

Q 19.

A population of Paramoecium caudatum was grown in a culture medium. After 5 days the culture medium became pvercrowded with Paramoecium and had depleted nutrients. What will happen to the population and what type of growth curve will the population attain? Draw the growth curve.

Q 20.

Give a suitable example for commensalism.

Q 21.

Emergent land plants that can tolerate the salinities of the sea are called

Q 22.

Define heliophytes and sciophytes. Name a plant from your locality that is either heliophyte or sciophyte.

Q 23.

How is diapause different from hibernation?

Q 24.

What is diapause and its significance?

Q 25.

List any three important characteristics of a population and explain.

Q 26.

Species that can tolerate wide range of salinity are called .

Q 27.

ncert-exemplar-problems-class-12-biology-organisms-and-populations-6
a. Label the three tiers 1, 2, 3 given in the above age pyramid.
b. What type of population growth is represented by the above age pyramid?

Q 28.

If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?

Q 29.

In an association of two animal species, one is a termite which feeds on wood and the other is a protozoan Trichonympha present in the gut of the termite. What type of association they establish?

Q 30.

Observe the set of 4 figures A, B, C and D, and answer the following questions: •
(i) Which one of the figures shows mutualism?
(ii) What kind of association is shown in D?
(iii) Name the organisms and the association in C.
(iv) What role is the insect performing in B?
ncert-exemplar-problems-class-12-biology-organisms-and-populations-9

Q 31.

Write a short note on
(a)Adaptations of desert plants and animals
(b)Adaptations of plants to water scarcity
(c)Behavioural adaptations in animals
(d)Importance of light to plants
(e)Effect of temperature or water scarcity and the adaptations of animals.

Q 32.

What is high altitude sickness? Write its symptoms.

Q 33.

The following diagrams are the age pyramids of different populations. Comment on the status of these populations.
ncert-exemplar-problems-class-12-biology-organisms-and-populations-12

Q 34.

Define ectoparasite and endoparasite, and give suitable examples.

Q 35.

If a fresh water fish is placed in an aquarium containing sea water, will the fish be able to survive? Explain giving reasons.

Q 36.

Why do submerged plants receive weaker illumination than exposed floating plants in a lake?

Q 37.

In an association of two animal species, one is a termite which feeds on wood and the other is a protozoan Trichonympha present in the gut of the termite. What type of association they establish?

Q 38.

Define zero population growth rate'. Draw an age pyramid for the same.

Q 39.

Define phenotypic adaptation. Give one example.

Q 40.

Last the attributes that populations but not individuals possess.

Q 41.

What are Eurythermic species?

Q 42.

In a pond, we see plants which are free-floating; rooted-submerged; footed emergent; rooted with floating leaves. Write the type of plants against each of them.
ncert-exemplar-problems-class-12-biology-organisms-and-populations-5

Q 43.

Give one example for each of the following:
(i) Eurythermal plant species ………………
(ii) A hot water spring organism ………………
(iii) An organism seen in deep ocean trenches ………………
(iv) An organism seen in compost pit ………………
(v) A parasitic angiosperm ………………
(vi) A stenothermal plant species ………………
(vii) Soil organism ………………
(viii) A benthic animal ………………
(ix) Antifreeze compound seen in antarcticfish ………………
(x) An organism which can conform ………………

Q 44.

If a marine fish is placed in a fresh water aquarium, will the fish be able to survive? Why or why not?

Q 45.

Most living organisms cannot survive at temperature above 45 °C. How are some microbes able to live in habitats with temperatures exceeding 100 °C?

Q 46.

An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?

Q 47.

Define stenohaline species.

Q 48.

Define aestivation.

Q 49.

What are the organisms that feed on plant sap and other plant parts called?

Q 50.

Give the scientific names of any two micro organisms inhabiting the human intestine.