The diagram below shows a phase during meiosis in an animal cell - NSC Life Sciences - Question 2 - 2021 - Paper 1

The phase represented in the diagram is metaphase.

Homologous chromosomes are pairs of chromosomes that have the same structure, length, and genes at corresponding loci. One chromosome of each pair is inherited from each parent.

The chromosomes appear as X-shaped structures because they are duplicated chromatids that are held together at their centromeres. During the crossing over in prophase I, segments of DNA may be exchanged between homologous chromosomes, resulting in chromatids with a mixture of genetic material from both parents.

Part A, which represents the spindle fibers, functions to contract and pull the chromosomes apart to the opposite poles of the cell during anaphase.

The parent cell had 48 arbitrary units of DNA before the division, as each daughter cell ends up with 12 units and there are two daughter cells formed.

Part B is identified as the sweat gland.

Structure A, representing blood vessels, constricts to reduce blood flow to the surface of the skin, thereby decreasing heat loss to the environment. This helps to maintain body temperature.

Temperature needs to be kept constant in the human body to ensure that enzymatic processes function optimally. Deviations from the normal body temperature can lead to denaturation of enzymes and proteins, affecting metabolic reactions.

The gland that secretes ADH (Antidiuretic Hormone) is the pituitary gland.

On a cold day, the body conserves water by reabsorbing it in the kidneys. The secretion of ADH is decreased, leading to less urine production and conserving water in the body.

For the individual resistant to the effects of ADH, the body compensates by increasing the levels of ADH in response to the higher osmolarity of the blood, attempting to re-establish normal hydration levels.

The type of fertilisation in guppies is internal fertilisation.

1. Internal fertilisation allows sperm to be deposited directly inside the female's body, increasing the chances of successful fertilisation.
2. Gametes are safeguarded within the female's body, protecting them from environmental threats and predators.

Guppies are regarded as ovoviviparous because the fertilised eggs develop within the female's body until they hatch, and the young are born live, retaining many characteristics of oviparous organisms.

Progesterone helps maintain the endometrium, ensuring the pregnancy continues. It prepares the uterus and prevents contractions that could lead to premature delivery.

The independent variable is the administration of progesterone treatment (or the dosage and frequency of injections).

The dependent variable is the glucose levels of the pregnant women, measured to assess the development of gestational diabetes.

They determined whether participants in Group A had developed gestational diabetes by closely monitoring and recording their glucose levels daily during the study.

1. The dosage was kept constant at 250 mg of progesterone.
2. The frequency of injections was kept constant, occurring once a week.

Group B acts as a control group to provide a baseline to compare against Group A. By not receiving progesterone treatment, it allows for the assessment of how effective the treatment was in preventing gestational diabetes.