Assertion: The concentration of methane in the atmosphere has more than doubled in the last 250 years.

Reason: Wetlands and rice fields are the major sources of methane.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: Escherichia coli, Shigella sp. and Salmonella sp. are all responsible for diarrhoeal disease.

Reason: Dehydration is common to al I types of diarrhoeal diseases and adequate supply of fluids electrolytes should be ensured.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: Deforestation is one main factor contributing to global warming.

Reason: Besides CO₂, two other gases methane and CFCs are also included under green house gases.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: An organism with lethal mutation may not even develop beyond the zygote stage.

Reason: All types of gene mutations are lethal.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: Inflammation of a skeletal joint may immobilize the movements of the joint.

Reason: Uric acid crystals in the joint cavity and ossification of articular cartilage lead to this

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: In tropical rain forests, O-horizon and A-horizon of soil profile are shallow and nutrient-poor.

Reason: Excessive growth of micro-organisms in the soil depletes its organic content.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: Polytene chromosomes have a high amount of DNA.

Reason: Polytene chromosomes are formed by repeated replication of chromosomal DNA without separation of chromatids.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: UV radiation causes photodissociation of ozone into O₂ and O₃ thus causing damage to the stratospheric ozone layer.

Reason: Ozone hole is resulting in global warming and climate change.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: The earliest organisms that appeared on the Earth were non-green and presumably anaerobes.

Reason: The first autotrophic organisms were the chemoautotrophs that never released oxygen.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Assertion: LSD and marijuana are clinically used as analgesics.

Reason: Both these drugs suppress brain function.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.