Some students, during a study, caught, marked and released 80 fishes in a pond. Later

100 fishes were caught at random. Among these 40 were found to be marked. What is

the approximate number of fishes in the pond?

1. 50                   

2. 100

3. 200                 

4.  4000

The sphere of living matter together with water, air and soil on the surface of earth is

called

1. atmosphere                       

2. hydrosphere

3. lithosphere                       

4. biosphere

Mutualism is found in 

1. Hermit crab and sea anemone

2. Ox pecker and rhinoceros

3. Zoochlorellae and Hydra

4. E.coli and man.

July 11 is observed as:

1. World population day

2. No tobacco day

3. World environment day

4. World health day

Which one of the following is a matching pair of certain organism(s) and the kind of

association?

1. Shark and sucker fish - predation

2. Algae and fungi in lichens - mutualism

3. Orchids growing on trees - parasitism

4. Cuscuta (dodder) growing in other flowering plants - epiphytism 

The Great Barrier Reef along the east coast of Australia can be categorised as

1. population       

2. community

3. ecosystem       

4. biome

If the Bengal Tiger becomes extinct

1. Hyenas and wolves will become scars

2. The wild areas will be safe for man and domestic animals

3. Its gene pool will be lost forever

4. The population of beautiful animals like deers will get stabilized. 

Which one of the following correctly represents an organism and its ecological niche?

(1) Vallisneria and pond

(2) Desert locust (Schistocerca) and desert

(3) Plant lice (aphids) and leaf

(4) Vultures and dense forest

In an experiment, freshly hatched larvae of an insect (Khapra beetle) were reared on a basal diet ( complete diet without cholesterol) with increasing amounts of cholesterols. Results obtained are shown in the graph given in the table:

The graph indicates that

(1) Cholesterol is an essential dietary requirement of Khapra beetle

(2) Growth of Khapra beetle is directly proportional to cholesterol concentration

(3) Cholesterol concentration of 2 ug/g is the optimum level.

(4) Growth of Khapra beetle is inhibited when cholesterol concentration exceeds 5ug/g diet.

Two opposite forces operate in the growth and development of every population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called

(1) Fecundity

(2) Environmental resistances

(3) Biotic control

(4) Mortality