The correct sequence of plants in a hyrdosere is 

1. Oak→Lantana →Scirpus→Pistia→Hydrilla→Volvax
2. Volvax→Hydrilla→Pistia→Scirpus→Lantana→Oak
3. Pistia→Volvax→Scirpus→Hydrilla→Oak→Lantana
4. Oak →Lantana→Volvax→Hydrilla→Pistia→Scirpus

About 70% of total global carbon is found in

1. grasslands

2. agro-ecosystems

3. oceans

4. forests

The slow rate of decomposition of fallen logs in nature is due to their

1. low moisture content

2. poor nitrogen content

3. anaerobic environment around them

4. low cellulose content

Consider the following statements concerning food chains

(i) Removal of 80% tigers from an area resulted in greatly increased growth of

vegetation

(ii) Removal of most of the carnivores resulted in an increased population of deers

(iii) The length of food chains is generally limited to 3-4 trophic levels due to energy loss

(iv) The length of food chains may vary from 2 to 8 trophic levels

Which two of the above statements are correct?

1. ii and iii

2. iii and iv

3. i and iv

4. i and ii

Quercus species are the dominant component in

1. temperate deciduous forests

2. alpine forests

3. scrub forests

4. tropical rain forests

Which of the following ecosystem types has the highest annual net primary productivity ?

1. Tropical rain forest

2. Tropical deciduous forest

3. Temperate evergeen forest

4. Temperate deciduous forest

Which one of the following is not used for construction of ecological pyramids?

1. Dry weight

2. Number of individuals

3. Rate of energy flow

4. Fresh weight

In a lake that undergoes thermal stratification, blooms of phytoplankton tend to occur

1. before thermal stratification 

2. after thermal stratification 

3. at the onset of thermal stratification 

4. at the mid-phase of thermal stratification 

Photosynthesis is absent in 

1. aphotic layer                 

2. photic layer        

3. benthic layer                 

4. pelagic layer.

The given type of ecological pyramid represents

1. pyramid of numbers in tree ecosystem

2. pyramid of biomass in a fallow land 

3. pyramid of biomass in a lake

4. energy pyramid in a spring