21.

What is common between chloroplasts, chromoplasts and leucoplasts

• Presence of pigments

• Possession of thylakoids and grana

• Storage of starch, proteins and lipids

• Ability to multiply by a fission-like process

Assertion: Our body secretes adrenaline in intense cold.

Reason: Adrenaline raises metabolic rate.

• 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: When the ambient temperature is high and soil contains excess of water, the plants tend to lose water in the form of droplets from lenticels.

Reason: Root pressure regulates the rate of loss of water form lenticels

• 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 angiosperms the conduction of water is more efficient because their xylem has vessels.

Reason: Conduction of water by vessel elements is an active process with energy supplied by xylem parenchyma rich in mitochondria

• 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: Gram-negative bacteria do not retain the stain when washed with alcohol.

Reason: The outer face of the outer membrane of Gram-negative bacteria contains lipopolysaccharides, a part of which is integrated into the membrane lipids

• 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: Under conditions of high light intensity and limited CO₂ supply,
photorespiration has a useful role in protecting the plants from photo-oxidative damage.

Reason: If enough CO₂ is not available to utilize light energy for carboxylation to proceed, the excess energy may not cause damage to plants.

• 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: Photosynthetically C₄ plants are less efficient than C3 plants.

Reason: The operation of C₄ pathway requires the involvement of only bundle-sheath cells.

• 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 falsen

• If both assertion and reason are false.

Assertion: Eukaryotic cells have the ability to adopt a variety of shapes and carry out directed movements.

Reason: There are three principal types of protein filaments - microfilaments, microtubules and intermediate filaments, which constitute the cytoskeleton.

• 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.

Which one of the following pairs of features is a good example of polygenic inheritance

• Human height and skin colour

• ABO blood group in humans and flower colour of Mirabilis jalapa

• Hair pigment of mouse and tongue rolling in humans

• Human eye colour and sickle cell anaemia

Mating of an organism to a double recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is called

• reciprocal cross

• dihybrid crossn

• test cross

• back cross