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

The phase represented in the diagram is metaphase.

Homologous chromosomes are a pair of chromosomes that have the same structure and length, containing the same sequence of genes. One is inherited from the maternal parent and the other from the paternal parent.

The chromosomes in the diagram appear as replicated structures. Each chromosome consists of two sister chromatids that are joined at the centromere. During meiosis, crossing over can occur where homologous chromosomes exchange genetic material, leading to genetic diversity.

Since each daughter cell contains 12 arbitrary units of DNA, the parent cell must have had a total of 48 arbitrary units of DNA at the beginning of the cell division.

Part B is identified as a sweat gland.

Structure A, which is a blood vessel, will constrict to reduce blood flow towards the surface of the skin. This reduces heat loss and helps to maintain the body temperature in cold conditions.

Temperature needs to be kept constant in the human body because enzymes function optimally at a specific temperature (around 37°C). Any deviations can lead to enzyme denaturation or loss of activity, affecting metabolic processes.

The pituitary gland secretes ADH.

On a cold day, the body conserves water by reabsorbing it in the kidneys while reducing the amount of sweat produced. This is largely controlled by ADH, which promotes water reabsorption in the renal tubules.

In this person's case, the renal tubules are resistant to the effects of ADH. Consequently, water is not reabsorbed effectively, leading to the production of large volumes of dilute urine, which results in abnormally low ADH levels.

The type of fertilisation in guppies is internal fertilisation.

1. Internal fertilisation allows sperm to be deposited directly inside the female, which increases the chances of successful fertilisation by minimizing the risk of environmental factors affecting sperm and eggs.
2. The fertilised eggs remain in the female’s body until they are ready to hatch, providing protection from predators and environmental dangers, leading to a higher survival rate for the offspring.

Guppies are regarded as ovoviviparous because the fertilised eggs develop inside the female's body, and the young are born live, rather than laying eggs externally.

The injection of progesterone is a good treatment to prevent premature delivery as it maintains the lining of the uterus, thus supporting the pregnancy and preventing contractions that could lead to early labor.

The independent variable is the dosage of progesterone administered to the participants.

The dependent variable is the glucose levels measured in the participants.

The investigators determined if participants from Group A developed gestational diabetes by measuring their glucose levels daily. A sustained increase in glucose levels would indicate the development of the condition.

1. The dosage of progesterone given was kept constant at 250 mg.
2. The timing of the injection was kept constant for all participants, occurring between weeks 16 and 20 of gestation.

Group B serves as the control group, which helps to establish a baseline for comparison against Group A. This allows researchers to determine the effects of progesterone treatment specifically, as any changes in glucose levels can be attributed to the treatment compared to a group that did not receive it.