Identify the stage of meiosis.

Metaphase I is a stage in meiosis where homologous chromosomes align at the metaphase plate.

During prophase I, crossing over occurs between homologous chromosomes, leading to genetic variation. Each chromosome at metaphase I consists of two sister chromatids, making it a double-threaded chromosome.

Therefore, chromosomes in metaphase I are double-threaded and show variation due to crossing over.

The correct option is C.

Question 1.1.2

• (i) Diffusion of oxygen from the mother to the foetus: This is a primary function of the placenta, facilitating gas exchange. (Correct)
• (ii) Production of progesterone: The placenta produces hormones like progesterone to maintain pregnancy. (Correct)
• (iii) Diffusion of excretory wastes from the mother to the Foetus: This is incorrect. Excretory wastes diffuse from the foetus to the mother for elimination. (Incorrect)
• (iv) Diffusion of nutrients from the mother to the foetus: The placenta transfers essential nutrients from the mother to the developing foetus. (Correct)

The correct functions are (i), (ii), and (iv).

The correct option is B.

Question 1.1.3

Kangaroos are mammals, and mammals typically undergo internal fertilisation, where the sperm fertilizes the egg inside the female's body.

The description states "has a gestation period of 33 days. It then gives birth to an offspring." This indicates that the embryo develops inside the mother's body and is born live, which is characteristic of viviparous reproduction.

Red kangaroos exhibit internal fertilisation and are viviparous.

The correct option is A.