Science (English Medium) कक्षा १२ - CBSE Important Questions for Biology

Answer the following question.
Mention the term used to describe a population interaction between an orchid growing on a forest tree.

Name and explain the interaction that is seen between clownfish and sea anemones.

Study the flow chart given below and complete the equation that follows by identifying 1, 2, 3 and 4.

N_{t + 1} = N_t + {(1+ 2) − (3 + 4)}

Mention the different ways by which the population density of different species can be measured.

Substantiate by giving two reasons as to why a holistic understanding of the flora and fauna the cropland is required before introducing an appropriate biocontrol method.

With the decline in the population of fig species it was noticed that the population of wasp species also started to decline. What is the relationship between the two and what could be the possible reason for decline of wasps?

What is mycorrhiza?

Sea Anemone gets attached to the surface of the hermit crab. The kind of population interaction exhibited in this case is ______.

Given below is the Age Pyramid of the population in one of the states in India as per 2011 census. It depicts the male population on the left-hand side, female population on the right-hand side, newborns towards the base and gradually increasing age groups as we move from base to the top, with the oldest population at the top. Study this pyramid and comment upon the appropriateness of the Assertion and the Reason.

                              Percentage to the total population

Assertion: It is a stable population.

Reason: The pre-reproductive and reproductive individuals are almost in equal numbers and the post-reproductive individuals are relatively fewer.

Write the observations made at the end of Connell's field, experiment on barnacles on the rocky sea coasts of Scotland.

Name any two categories of organisms that in general are adversely affected by competition.

What would be the best method to measure the total population density of a dense bacterial culture in a petridish and why?

What would be the best method to measure the total population density of the number of fishes in river and why?

Interaction between clown fish living among the stinging tentacles of sea anemone is an example of ______.

"Abingdon tortoise in Galapagos islands became extinct within a decade on introduction of goats in the island." Explain giving reason.

Many copepods live on the body surface of marine fish. This relationship is an example of ______.

"Some species of insects and frogs have evolved with various specific features that help them from being detected."

1. Justify the statement giving reasons.
2. Mention any two such features.

Observe the graph given below.

a) Which species is competitively superior? Support it with the data provided in the graph.

b) State the underlying principle for the above result and name the scientist associated with this principle.

c) Explain the mechanism in which two or more species competing with each other can co-exist.

OR

Graphs A and B shown below depict interaction of two species. Which graph indicates Mutualism? Give reason.

A	B

Write the equation that helps in deriving the net primary productivity of an ecosystem.

Why the pyramid of energy is always upright? Explain.