Describe the role of auxins in phototropism when a plant is exposed to unilateral light.

Here are the answers to your questions:

3.1 Describe the role of auxins in phototropism when a plant is exposed to unilateral light.
When a plant is exposed to unilateral light, auxins, which are plant hormones produced in the shoot tip, migrate to the shaded side of the shoot. The higher concentration of auxins on the shaded side promotes faster cell elongation on that side compared to the illuminated side. This differential growth causes the shoot to bend towards the light source.

3.2 FSH Investigation Analysis

3.2.1 State TWO factors, regarding the females, that should have been kept constant during the investigation.

• Health status (all healthy).
• Not using hormone-based contraceptives.
• Day of the menstrual cycle when FSH was measured (Day 3).
• Number of cycles over which FSH was measured (5 cycles).
• Number of participants in each age group (250).

3.2.2 State TWO ways in which the reliability of the results was ensured.

• A large sample size was used (1000 females in total, 250 per group).
• FSH levels were measured over 5 cycles and an average was calculated.
• Measurements were taken on the same day (Day 3) of the menstrual cycle for all participants.

3.2.3 State ONE conclusion that can be drawn from the results.

• As the age of females increases, their average FSH levels also increase.

3.2.4 Explain why the oestrogen levels may remain low in the blood of the females in the 41-50 age group.
The high FSH levels in the 41-50 age group indicate that the ovaries are less responsive or have fewer remaining follicles. Since developing follicles are the primary source of oestrogen, a decline in ovarian function leads to lower oestrogen production. This is characteristic of perimenopause or menopause.

3.2.5 Explain why females that were using progesterone-based pills were excluded from the investigation.
Progesterone-based pills contain synthetic hormones that suppress the natural production of FSH by the pituitary gland through negative feedback. Including these females would have introduced a confounding variable, leading to artificially low FSH readings that would not accurately reflect their natural ovarian function or age-related changes.

3.3 Describe the development of the placenta and umbilical cord from the time of implantation.
After implantation, the outer layer of the blastocyst, called the trophoblast, develops into the chorion. The chorion forms finger-like projections called chorionic villi that extend into the uterine lining (endometrium). These villi interdigitate with the maternal blood vessels and tissues, forming the placenta. The placenta facilitates the exchange of nutrients, oxygen, and waste products between the mother and the developing embryo/fetus, and also produces hormones.

Simultaneously, the allantois and yolk sac (extra-embryonic membranes) contribute to the formation of the umbilical cord. The umbilical cord connects the fetus to the placenta and contains two umbilical arteries (carrying deoxygenated blood and waste from the fetus) and one umbilical vein (carrying oxygenated blood and nutrients to the fetus).