Rajesh observed a patch of greenish black powdery mass on a stale piece of bread.
(i) Name the organism responsible for this and its specific mode of asexual reproduction.
(ii) Name its vegetative and reproductive parts.

How is ozone formed in the upper atmosphere? State its importance. What is responsible for its depletion? Write one harmful effect of ozone depletion.

DDT was sprayed in a lake to regulate breeding of mosquitoes. How would it affect the trophic levels In the following food chain associated with a lake? Justify your answer. 

List any four methods of contraceptions used by humans. How does their use have a direct effect on the health and prosperity of a family?

Give any two ways in which biodegradable substances would affect the environment.

Why is vegetative propagation practiced for growing some types of plants?

State one ill-effect of the absence of decomposers from a natural ecosystem.

(a) Name the parts labelled A, B, C, D, and E
(b) Where do the following functions occurs?
(i) Production of an egg
(ii) Fertilisation
(iii) Implantation of zygote
(c) What happens to the lining of uterus
(i) before release of fertilised egg. (ii) if no fertilisation occurs

Which of the following will have the maximum concentration of harmful chemicals in its body?
Peacock, Frog, Grass, Snake, Grasshopper.

If all the waste we generate is biodegradable, will this have no impact on the environment?

Differentiate between 'Self-pollination' and 'Cross-pollination'. Describe double fertilisation in plants.

How is the process of pollination different from fertilisation?

Consider the following statements about ozone.
(A) Ozone is a poisonous gas.
(B) Ozone shield the earth surface from the infrared radiations in the Sun.
(C) Ozone is a product of UV radiation acting on oxygen molecules.
(D) At the lower level of the earth atmosphere ozone performs most essential function.
The correct statements are

Which of the following constituents do not form ecosystem?

The full form of AIDS is

The process where the unfertilised egg is released out of the body with the blood used to nourish the embryo is known as

The decomposers in an ecosystem

In a food chain, the third trophic level is always occupied by

Which among the following diseases is not sexually transmitted?

During adolescence, several changes occur in the human body. Mark one change associated with sexual maturation in boys

Assertion (A) Offspring produced by asexual reproduction are genetically similar to the parents.
Reason (R) Asexual reproduction involves a single parent.
(a) If both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

Assertion: Ozone, is a deadly poison at the ground level.
Reason: Ozone at the higher levels of the atmosphere is protective in nature.
Codes
(a) If both assertion and reason are true and the reason is correct explanation of assertion.
(b) If both assertion and reason are true but reason is not a correct explanation of assertion.
(c) If assertion is true and reason is false.
(d) If both assertion and reason are false.

Assertion: Harmful chemicals enter our bodies through the food chain.
Reason: The highest member in the food chain has the least amount of chemical.
Codes
(a) If both assertion and reason are true and the reason is correct explanation of assertion.
(b) If both assertion and reason are true but reason is not a correct explanation of assertion.
(c) If assertion is true and reason is false.
(d) If both assertion and reason are false.

Assertion: The ovary releases one egg every month.
Reason: This process is repeated every month and is called menstruation.
Codes
(a) If both assertion and reason are true and the reason is correct explanation of assertion.
(b). If both assertion and reason are true but reason is not a correct explanation of assertion.
(c) If assertion is true and reason is false.
(d) If both assertion and reason are false

In any given ecosystem, all living organisms are linked in a systematic chain with respect to their mode of manufacturing food/feeding habits. This sequential interlinking of organisms involving transfer of food energy from producers through a series of organisms with repeated eating and being eaten is called the food chain. A food chain may have 3-4 trophic levels.
(i) Which of the following statements regarding food chain is incorrect?
(a) It is a single straight pathway through which food energy travels in the ecosystem.
(b) It adds adaptability and competitiveness to the organisms.
(c) Presence of isolated food chains adds to instability of the ecosystem.
(d) Food chain binds up inorganic nutrients of the ecosystem.
(ii) Consider the following food chain.
Grass \(\longrightarrow\)A \(\longrightarrow\)Frog \(\longrightarrow\) Snake\(\longrightarrow\)Eagle
Which of the following can be placed at A?

(iii) Select the correct food chain.
(a) Aquatic plants \(\longrightarrow\) Tadpole \(\longrightarrow\)Water beetle\(\longrightarrow\)Pike\(\longrightarrow\)Perch
(b) Grass\(\longrightarrow\)Grasshopper\(\longrightarrow\)Snake\(\longrightarrow\) Frog\(\longrightarrow\) Eagle
(c) Grass\(\longrightarrow\) Rabbit\(\longrightarrow\) Wild cat\(\longrightarrow\) Tiger
(d) Zooplankton \(\longrightarrow\) Phytoplankton \(\longrightarrow\)Small fish\(\longrightarrow\)Fish
(iv) Food chains are sustained by producers and _____________.

(v) Select the incorrect statement.
(a) Food chain may terminate at level of herbivore
(b) Food chain is always straight
(c) Food chain may have 3-5 trophic levels
(d) In a food chain, 80 to 90% of potential energy is lost as heat, at each transfer

A newly married couple does not want have children for few years. They consulted a doctor who advised them barrier method and chemical method of birth control. Yet another couple who already have two children and are middle aged also consulted doctor for some permanent solution to avoid unwanted pregnancy. Doctor advised them surgical method of birth control.
(i) What are the barrier methods of birth control?

(ii) How physical barrier prevent pregnancy?
(a) They kill the sperms
(b) They kill the ovum
(c) They prevent sperms from meeting the ovum
(d) They prevent intercourse
(iii) How chemical methods prevent pregnancy?
(a) Vaginal pills contain chemical called spermicides which kill the sperms
(b) Oral pills prevent ovulation so there will be no fertilisation
(c) Oral pills stop menstruation in females
(d) Both (a) and (b)
(iv) Select the correct statement regarding surgical method of birth control.
(a) It involves termination of pregnancies in women particularly after eight weeks of conception
(b) Small portion of sperm duct or vas deferences in males is removed by surgical operation and both cut ends are ligated properly
(c) Small portion of oviducts in females is removed by surgical operation and cut ends are ligated
(d) Both (b) and (c)
(v) Select the correct statement regarding birth control methods.
(a) Barrier method of birth control also protects the couple from sexually transmitted diseases
(b) Some women experience unpleasant side effects on taking oral pills because of change in hormonal balance in body
(c) Surgical method in males is called vasectomy and in females is called tubectomy
(d) All of these

Given reason for the following.
(i) Name a unisexual and a bisexual flower.
(ii) Define cross-pollination. sate how it is carried out?
(iii) Observe the diagram given below and name the parts marked as 'A' and 'B'.

Mention the function of each of these parts.

Why is Government of India imposing a ban on the use of polythene bags? Suggest two alternatives to these bags and explain how this ban is likely to improve the environment?