1. What is Apical dominance?
Ans: The phenomenon of the suppression of the growth of lateral buds by the terminal bud is known as “Apical dominance”
2. How trachea is prevented from collapsing?
Ans: The walls of trachea are supported by several ‘c’ shaped cartilaginous rings. They prevent the trachea from collapsing and closing.
3. What is a mixed gland? Give an example.
Ans: The gland which acts as an exocrine as well as endocrine gland is called a mixed gland. e.g.: Pancreas
4. Why there is more pressure in arteries than in veins.
Ans: The arteries receive the blood from heart. So, blood pressure is more in arteries than in veins.
5. What are ‘gyri’ and ‘sulci’? What is the advantage of these structures?
Ans: The outer portion of cerebral hemisphere is called cerebral cortex. It consists of several ridges called ‘gyri’ and the grooves called ‘sulci’. They increase the surface area of the cortex so that it can accommodate more number of neurons.
6. What is blood transfusion?
Ans: Administering of blood from one person to another person through vein is called blood transfusion.
7. What is “Heart Attack”?
Ans: There are a pair of coronary arteries. They carry oxygenated blood to the heart muscles. In some people, the coronary arteries get blocked with age. When this happens muscle cells in the heart do not recieve oxygenated blood and stop working. This is called heart attack.
8. What is an electron acceptor? Give some examples.
Ans: The substance which accepts the electrons is called an electron acceptor.
e.g.: (1) Nicotinamide Adenine Dinucleotide (NAD)
(2) Nicotinamide Adenine Dinucleotide Phosphate (NADP)
(3) Cytochromes
(4) Plasto quinones
(5) Fermredoxins etc
9. What are the differences between a dendrite and an axon?
Ans:
Dendrite – Axon
1. Dendrites are short and branched. 1. Axon is long and unbranched.
2. One to thousand of dendrites are 2. Only one axon is
present in each neuron. present in each neuron.
3. Dendrites arise from all the 3. Axon arise from one
corners of neuron. corner of the neuron.
4. They transmit information from 4. They receive information and
one cell to cell or effector organ transmit it to the cell body.
10. What are the functions of cytokinins?
Ans: 1. Cytokinins are a group of substances produced by plants and are capable of stimulating cell division and cell elongation.
2. These substances are produced in actively growing tissues of the plants like roots, embryos and developing fruits.
3. In mature plants cytokinins are made in the roots and transported to the shoots.
4. Cytokinins promote cell division.
5. Cytokinins have the ability to delay the process of aging in leaves.
6. Cytokinins prolong the life of fresh leaf crops like cabbage, spinach etc.
7. They are useful in keeping the flowers fresh.
8. Sometimes they are also used to break the dormancy of seeds.