3.1.1 During which month was the abscisic acid concentration the lowest? 3.1.2 Explain the trend of the graph from March to May - NSC Life Sciences - Question 3 - 2023 - Paper 1

From March to May, the abscisic acid concentration increases steadily. This is due to the tree preparing for the onset of warmer temperatures as it approaches spring, requiring higher levels of abscisic acid for growth and development.

The dormancy in cherry trees during the winter months can be attributed to decreased sunlight, resulting in lower photosynthesis rates, which minimizes energy demands and allows the tree to conserve resources.

Auxins play a critical role in the development of roots by promoting downward growth or positive geotropism. They stimulate the elongation of cells on the lower side of the root, enhancing root growth and anchorage in the soil.

When a plant is placed horizontally, auxins accumulate on the lower side of the stem, causing cell elongation which leads to upward growth of the stem. In contrast, auxins in the roots inhibit growth on the lower side, causing the roots to bend downwards.

The gland that secretes aldosterone is the adrenal gland.

The independent variable is the aldosterone level/increased aldosterone level.

The dependent variable is the blood pressure.

1. The study involved 1,688 volunteers, providing a large sample size, which enhances the validity of the results.
2. The procedure was done four times for each individual, ensuring consistent data collection.

1. A controlled diet ensures that dietary factors do not influence the results of blood pressure measurements.
2. It helps in maintaining the consistency of other potential variables that could affect the outcomes.

Participants’ blood pressure was measured before the start to establish a baseline for comparison against measurements taken after the administration of aldosterone.

After injection of aldosterone, the permeability of the renal tubules increases for salt, leading to greater resorption of sodium and thus, a decrease in salt levels in the urine.

Adrenaline secretion stimulates the conversion of glycogen to glucose, increasing blood glucose levels, which provides immediate energy. It also enhances heart rate, deepens breathing, and redistributes blood flow to vital organs, all contributing to heightened readiness and energy efficiency.

Structure F is the iris.

1. Fluid A helps to maintain the shape of the eye.
2. It plays a role in refraction of light, allowing the eye to focus clearly.

Area B contains a high concentration of photoreceptors, while area C does not contain photoreceptors or rods and cones, which are essential for light detection.

The visual defect is known as astigmatism.

If cataracts develop in part D, the lens may become clouded, leading to blurred vision as less light can pass through, disrupting clear sight.

When an object is less than 6 metres away, the ciliary muscles contract, which thickens the lens, allowing it to become more rounded. This change in shape increases its refractive power, enabling the eye to focus clearly on nearby objects.