Which domestic sewage mixes with river water

• small animals like rats will die after drinking river water

• the increased microbial activity releases micronutrients such as iron

• the increased microbial activity uses up dissolved oxygen

• the increased microbial activity uses up dissolved oxygen

An imporved variety of trasgenic basmati rice

• does not require chemical fertilisers and growth hormones

• gives high yield nd is rich in vitamin-A

• is completely resistant to all insect pests and diseases of paddy

• is completely resistant to all insect pests and diseases of paddy

The breakdown of detritus into smaller particles by earthworm is a process called 

• humification 

• fragmentation

• mineralisation

• mineralisation

The Indian rhinoceros is a natural inhabitant of which one of the Indian states?

• Uttarakhand

• Uttar Pradesh

• Himachal Pradesh

• Himachal Pradesh

The biomass available for consumption by the herbivores the decomposers is called

• net primary productivity

• secondary productivity

• standing crop

• standing crop

DDT residues are rapidly passed through food chain causing biomagnification because DDT is 

• liposoluble

• moderately toxic

• non-toxic to aquatic animals

• non-toxic to aquatic animals

Study the four statements (1-4) given below and select the two correct one out of them.

1. A lion eating a deer and a sparrow feeding on grain are ecologically similar in being consumers
2.Predator starfish pisaster helps in maintaining species diversity of some invertebrates
3.Predators ultimately lead to the extinction of prey species
4.Production of chemicals such as nicotine, strychnine by the plants are metabolic disorders

The two correct statements are 

• (2) and (3)

• (3) and (4)

• (1) and (4)

• (1) and (4)

Both, hydrarch and xerarch successions lead to

• medium water conditions

• xeric conditions

• highly dry conditions

• highly dry conditions

Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

• Phytoplankton 

• Fish

• Zoonplankton

• Zoonplankton

Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D.

• A	B	C	D
  Nitrification	Ammonification	Animals	plants

• A	B	C	D
  Dentirificiation	Ammonification	Plants	Animals

• A	B	C	D
  Nitrification	Denitrification	Animals	Plants

• A	B	C	D
  Nitrification	Denitrification	Animals	Plants