Question

Give reasons:

1. Ventricles have thicker muscular walls than atria.
2. The transport system in plants is slow.
3. The circulation of blood in aquatic vertebrates differs from that in terrestrial vertebrates.
4. During the daytime, water and minerals travel faster through xylem as compared to the night.
5. Veins have valves whereas arteries do not.

Answer 1

The reasons for the statements are:

Statement a:

1. The ventricles form the lower chambers of the heart.
2. The muscular walls of ventricles are thicker compared to atria as they have to pump blood out of the heart.
3. They pump blood at a higher pressure to ensure it reaches all parts of the body.

Statement b:

1. Transport in plants occurs via the xylem and phloem.
2. Xylem transports water and minerals to the leaves while the phloem translocates food items throughout the plant.
3. The transportation is slow as they have a high composition of dead cells and thus have low energy expenditure.

Statement c:

1. The circulation system is involved in the transportation of oxygenated and deoxygenated blood in the body.
2. The terrestrial animals intake oxygen from the air through the lungs, whereas aquatic animals take oxygen from the water via gills.
3. Thus, the circulatory system present in terrestrial vertebrates is different from that in aquatic vertebrates.

Statement d:

1. Transpiration occurs through stomata during the daytime.
2. Transpiration creates water pressure in the xylem.
3. This pressure pulls the water via the stem to the leaves.
4. Thus, water is transported faster through the xylem during the day.

Statement e:

Veins have valves, whereas arteries do not because valves have to prevent the backflow of blood in veins and ensure blood flow in one direction.