Breathing and Exchange of Gases — BIOLOGY STD 11 Science — Question

Differentiate between vascular tissues of gymnosperms and angiosperms.

While teaching about the chemistry of life, teacher emphasised that carbohydrates, fats, proteins, vitamins and minerals are important for life in addition to water. Akash was under the impression that fats are not good for body and high cholesterol content generally causes heart related and other problems. Therefore, he asked his father who is a doctor about the role of fats in living organisms.

1. What are fats?
2. What is the average percentage of fats present in a cell?
3. How many fatty acid residues are found in one molecule of fat?
4. What values are indicated from Akash's character?

Lenticels are loosely arranged areas in the periderm.

1. How these are formed?
2. What are their numbers?
3. How the lenticels help the plants?

Define chrysophytes. Why are they considered as the chief producers in the ocean?

Cell membrane is semi-permeable in nature and thus allows passage to selected substances through it. Which of the following can be learnt from this property of the cell membrane? What are the benefits of selectively learning or adapting certain things for us?

1. We should only eat selected food.
2. We should follow good behaviour only and avoid bad behavior.
3. We should pay respect to selected persons only.

The flow of impulse in a nerve is unidirectional. Give reason.

How do you sense changes in the environment?

What is chiasmata? Mention its significance also.

Specify the position of the Thebesian valve and His bundle.