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CBSE Class 12 Biology Organisms and Populations. CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers.
1.Identify the curves ‘a’ and ‘b’ shown in the graph given below. List the conditions responsible for growth patterns ‘a’ and ‘b’.
2 Why and when do some animals like frogs hibernate?
3 Mention any two significant roles predation plays in nature?
4 Why is the polar region not a suitable habitat for tiny humming birds?
5 Name the type of interaction seen between whale and the barnacles growing on its back.
6 Name the interaction in each of the following:
a. Cuckoo lays her eggs in the crow’s nest
b. Orchid grows on a mango tree
c. Ticks live on the skin of dogs.
7 Certain species of wasps are seen to frequently visit flowering fig trees. What type of interaction is seen between them and why?
8 Egrets are often seen along with grazing cattle. How do you refer to this interaction? Give a reason for this association.
9 a) What is “r” in the population equation given below: dN/dt=rN
b) How does the increase and decrease in the value of ‘r’ affect the population size?
10 How does the Mediterranean orchid Ophrys ensure its pollination by bees?
11 a) How is cuscuta adapted to be a parasitic plant?
b) Why do cattle avoid browsing on Calotropis plants? Explain.
d. Sea anemone is often found on the shell of hermit crab.
13 Why is predation required in a community of different organisms?
Ques. The sum total of the populations of the same kind of organisms constitute
(a) colony (b) genus
(c) community (d) species.
Ques. Fertility of soil is measured by its ability to
(a) retain nutrients
(b) hold organic materials
(c) hold water
(d) support life.
Ques. Soil particles determine its
(b) field capacity
(c) water holding capacity
(d) soil flora.
Ques. Homeostasis is
(a) tendency of biological systems to change with change in environment
(b) tendency of biological systems to resist change
(c) disturbance of self regulatory system and natural controls
(d) biotic materials used in homeopathic medicines.
Ques. Deep black soil is productive due to high proportion of
(a) sand and zinc (b) gravel and calcium
(c) clay and humus (d) silt and earthworm.
Ques. Homeostasis is
(a) tendency to change with change in environment
(b) tendency to resist change
(c) disturbance in regulatory control
(d) plants and animal extracts used in homeopathy.
Ques. Which of the following is not an attribute of a population?
(a) Sex ratio (b) Natality
(c) Mortality (d) Species interaction
Ques. Carnivorous animals lions and leopards, occupy the same niche but lions predate mostly larger animals and leopards take smaller ones. This mechanism of competition is referred to as
(a) character displacement
(c) resource partitioning
(d) competitive exclusion.
Ques. Between which among the following, the relationship is not an example of commensalism?
(a) Orchid and the tree on which it grows
(b) Cattle Egret and grazing cattle
(c) Sea Anemone and Clown fish
(d) Female wasp and fig species
Ques. Natality refers to
(a) death rate
(b) birth rate
(c) number of individuals leaving the habitat
(d) number of individuals entering a habitat.
Ques. Which one of the following plants shows a very close relationship with a species of moth, where none of the two can complete its life cycle without the other?
(a) Hydrilla (b) Yucca
(c) Banana (d) Viola
Ques. In a growing population of a country,
(a) pre-reproductive individuals are more than the reproductive individuals
(b) reproductive individuals are less than the postreproductive individuals
(c) reproductive and pre-reproductive individuals are equal in number
(d) pre-reproductive individuals are less than the reproductive individuals.
Ques. Which one of the following population interactions is widely used in medical science for the production of antibiotics?
(a) Commensalism (b) Mutualism
(c) Parasitism (d) Amensalism
Ques. Asymptote in a logistic growth curve is obtained when
(a) K = N
(b) K > N
(c) K < N
(d) the value of ‘r’ approaches zero.
Ques. Mycorrhizae are the example of
(a) amensalism (b) antibiosis
(c) mutualism (d) fungistasis.
Ques. Which of the following is correct for r-selected species?
(a) Large number of progeny with small size
(b) Large number of progeny with large size
(c) Small number of progeny with small size
(d) Small number of progeny with large size
Ques. If ‘+’ sign is assigned to beneficial interaction, ‘–’ sign to detrimental and ‘O’ sign to neutral interaction, then the population interaction represented by ‘+’ ‘–’ refers to
(a) mutualism (b) amensalism
(c) commensalism (d) parasitism.
Ques. The principle of competitive exclusion was stated by
(a) C. Darwin (b) G.F. Gause
(c) Mac Arthur (d) Verhulst and Pearl.
Ques. When does the growth rate of a population following the logistic model equal zero? The logistic model is given as dN/dt = rN(1–N/K)
(a) when N/K equals zero
(b) when death rate is greater than birth rate
(c) when N/K is exactly one
(d) when N nears the carrying capacity of the habitat.
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