Correct Answer: A) nephridia

Explanation

Earthworms are invertebrates that belong to the phylum Annelida. They are known to possess an excretory system that helps in removing waste materials from their body. The excretory organ of an earthworm is called nephridia. Nephridia are tiny, coiled tubes that are found in pairs in each segment of an earthworm's body. They are responsible for filtering waste products such as excess water, salts, and nitrogenous waste from the blood. These waste products are then excreted out of the body through tiny pores called nephridiopores present on the surface of the worm's body. Flame cells are found in the excretory system of flatworms, while malphiligan tubules are found in insects like grasshoppers, and chloragogenus cells are found in the body cavity of some invertebrates like annelids and arthropods. Kidneys are the excretory organs found in vertebrates, including humans. Therefore, the correct answer to this question is Option A: nephridia.

Correct Answer: D. vascular bundles

Explanation

The spongy mesophyll's function is to allow for the interchange of gases (CO 2) that are needed for photosynthesis.

Explanation

(a)To demonstrate the effect of auxin on growth of a plant shoot, cut off the growing tip of coleoptile or shoot of three potted maize seedlings A,B, and C. Get three agar blocks A.B.C. Place one of the cut tips on an agar block A, so that the auxins in the tip can diffuse into the agar block. Then put three drops of IAA or Synthetic auxin on agar blockB. Put agar blocks A and B on one side or on top of the cut tip of the coleoptile or shoot A and B respectively. Then place the untreated agar block C on the side or tip of third cut coleoptile or shoot tip C as control experiment. Leave the three coleoptiles or shoots in unilateral light for 12 to 36 hours. The Coleoptiles or Shoots carrying agar block A and B show growth curvature while C shows no growth curvature. This shows that auxin promotes growth

(b)The use of auxin in agriculture are:

(i) Auxin helps to induce ripening of fruits.

(ii) It also helps to produce lateral bud development in stem

(iii) It helps in controlling weeds as well as controlling flowering and fruiting in plants.

(v) It assists in breaking seed dormancy.

(vi) It helps to initiate adventitious roots in stem cuttings and for parthenocarpic fruiting.

(c) Mechanism of transmission of impulses through a nerve fibre is characterised by change in electrical, potential and ionic charge. When at rest, the outside of the nerve is positively charged while the inside is negatively charged. Chemically, the nerve fibres possess potassium ions which are concentrated inside the fibre, while sodium ions are concentrated more on the outside. The change in permeability of the cell membrane is brought about when the fibre is stimulated and sodium ions enter the nerve while potassium ions move to the outside. The change in permeability along the nerve or change in electrical potential and ionic change along the fibre cause the movement of the electrical current along the fibre. In this way, the impulse is propagated or transmitted while the original resting stage of the nerve is restored as soon as the impulse passes.

Correct Answer: B. mollusca

Explanation

The organism labelled IV is a Snail. Snails belong to the Phylum Mollusca. This phylum is characterized by soft-bodied animals that usually have an external shell, like snails, clams, and squids.

Correct Answer: C. All their daughters will be carriers

Correct Answer: A. Ability to respond to stimuli

Explanation

Irritability, also known as responsiveness or excitability, refers to the ability of cells to detect and respond to various stimuli or changes in their environment.

Correct Answer: A. dendrites

Correct Answer: C. of energy loss at each trophic level

Correct Answer: D) before every mitotic division

Explanation

This question is asking about where meiosis occurs in animals. Meiosis is a type of cell division that produces sex cells, such as sperm and eggs. The question is asking when this process occurs in animals. Option A suggests that meiosis occurs after fertilization. This is incorrect because fertilization occurs when a sperm cell and an egg cell join together to form a zygote, which then undergoes mitotic divisions. Option B suggests that meiosis occurs after every mitotic division. This is also incorrect because mitosis and meiosis are two different types of cell division. Mitosis produces two identical daughter cells, while meiosis produces four non-identical daughter cells. Option C suggests that meiosis occurs before fertilization. This is the correct answer because meiosis is the process that produces the haploid gametes (sperm and egg cells) that combine during fertilization to form a diploid zygote. Option D suggests that meiosis occurs before every mitotic division. This is incorrect because mitotic divisions produce identical daughter cells, while meiosis produces non-identical daughter cells. Option E suggests that meiosis occurs during fertilization. This is also incorrect because meiosis occurs before fertilization, not during it. In conclusion, the correct answer is option C: before fertilization. Meiosis is the process that produces haploid gametes before they combine during fertilization to form a diploid zygote.

Correct Answer: B. leaching, underground seepages and run-off