Benthic organisms are affected most by

Water-holding capacity of soil
Light reaching the forest floor
Surface turbulence of water
Sediment characteristics of aquatic ecosystems

Solution

The sediment characteristics often determine the type of benthic animals that can thrive there.

A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is :

15
05
zero
10

Solution

Net increase in population : (Natality + Immigration) – (Mortality + Emigration)(250 + 20) – (240 + 30) = 270 – 270 = 0

A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is :

Symbiosis
Commensalism
Amensalism
Ectoparasitism

Solution

Commensalism is an interaction where one species is benefitted and other is neither benefitted nor harmed.

What type of human population is represented by the following age pyramid?

Vanishing population
Stable population
Declining population
Expanding population

Solution

This age pyramid represents the declining population of any organism. Population decline is the reduction overtime in region’s census. It can be caused for several reasons that includes heavy immigration disease, famine or sub-replacement fertility.

The figure given below is a diagrammatic representation of response of organisms to a biotic factors. What do a, b and c represent respectively?

1-conformer; 2-regulator; 3-partial regulator
1-regulator; 2-partial regulator; 3-conformer
1-partical regulator; 2-regulator; 3-conformer
1-regulator; 2-conformer; 3-partial regulator

Solution

In the graph, the line a represents regulator, line b represents conformer and line c represents partial regulator. Organisms that are able to maintain homeostasis by physiological means that ensures constant body temperature are called regulators. Organism that are not able to maintain a constant internal temperature are called conformers.Partial regulators are organisms that have the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.

A country with a high rate of population growth took measures to reduce it. The Figure below shows age-sex pyramids of populations A and B twenty years apart.
Select the correct interpretation about them: Interpretations:

“B” is earlier pyramid and shows stabilised growth rate..
“B” is more recent showing that population is very young.
“A” is the earlier pyramid and no change has occurred in the growth rate.
“A” is more recent and shows slight reduction in the growth rate.

Solution

‘A’ is more recent and shows slight reduction in growth rate.

Cuscuta is an example of

ectoparasitism
brood parasitism
predation
endoparasitism

Solution

Cuscuta, or Dodder plant, is a parasitic plant that wraps around other plants for nourishment. Cuscuta is found on outer side of the host and is total stem parasite.

Consider the following four conditions (i) – (iv) and select the correct pair of them as adaptation to environment in desert lizards.

The conditions :

(i) Burrowing in soil to escape high temperature

(ii) Losing heat rapidly from the body during high temperature

(iii) Bask in sun when temperature is low

(iv) Insulating body due to thick fatty dermis

(iii) and (iv)
(i)
(iii), (ii) and (iv)
(i) and (ii)

Solution

Some species make permanent burrows deep into the soil to escape high temperature or sunlight and some cold blooded animals often like to bask in the sun to warm up their body.

Large woody vines are more commonly found in :

temperate forest
mangroves
tropical rainforests
alpine forests

Solution

Large woody vines are more commonly found in tropical rain forests. This is a common concern in the high humidity climatic condition.

Which one of the following is one of the characteristics of a biological community?

Stratification
Natality
Mortality
Sex ratio

Solution

Stratification is one of the characteristics of biological community. Natality, mortality, age, structure and sex ratio are basic characteristics of a population.

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