Everyday Biology Questions CBSE Class 9 Biology Worksheets Set 04

Questions with Answers

Question 1. Why do the leaves of the 'touch-me-not' plant curl up when touched?
Answer:
In Mimosa pudica, touch is a stimulus. Water quickly moves out of the swollen cells at the base of the leaf (pulvinus) into the spaces between cells. The cells lose turgor and the leaflets droop and fold. When the stimulus is gone, the cells regain water and the leaf opens again.
In simple words: Cells at the leaf base lose water and become limp, so the leaf folds.

Teacher's Note:
1. This is a touch-controlled (seismonastic) movement, not growth.
2. Turgor pressure keeps leaves firm; loss of turgor makes them droop.

Question 2. Who discovered that the malaria parasite is carried by mosquitoes?
Answer:
Sir Ronald Ross, a British doctor born in India, showed in 1897 that the malaria parasite is transmitted by the female Anopheles mosquito.
In simple words: Ronald Ross found that the Anopheles mosquito carries malaria.

Teacher's Note:
1. Only the female Anopheles mosquito spreads malaria.
2. The malarial parasite is Plasmodium.

Question 3. Flying fox is not a fox. Why?
Answer:
The flying fox is a fruit-eating bat. It is called a flying fox because its head, long snout and large eyes look like a fox, but it is a mammal of the order Chiroptera and not a member of the dog family.
In simple words: It is a large bat with a fox-like face.

Teacher's Note:
1. Bats are the only mammals capable of true flight.
2. Common names can be misleading; scientific classification is based on structure.

Question 4. Which is the smallest bone in the human body?
Answer:
The stapes (stirrup), one of the three tiny bones in the middle ear, is the smallest bone in the human body. The other two are the malleus and the incus.
In simple words: The stapes in the ear is the smallest bone.

Teacher's Note:
1. The three ear bones carry vibrations from eardrum to inner ear.
2. The femur (thigh bone) is the longest bone.

Question 5. What percentage of the total body weight of a normal person is blood?
Answer:
About 8 per cent of the body weight. For an adult this is about 5 to 6 litres.
In simple words: Blood is roughly 8 per cent of body weight.

Teacher's Note:
1. Blood is a fluid connective tissue.
2. A person of 60 kg has about 4.8 kg of blood.

Question 6. Which bird is referred to as the 'laughing jackass'?
Answer:
The kookaburra, an Australian kingfisher, whose loud call sounds like human laughter.
In simple words: The kookaburra.

Teacher's Note:
1. Birds are identified by their calls as well as their features.
2. Kookaburras belong to the kingfisher family.

Question 7. Which branch of biology deals with the study of bones?
Answer:
Osteology is the study of bones.
In simple words: Osteology.

Teacher's Note:
1. The human skeleton has 206 bones in an adult.
2. The study of muscles is called myology.

Question 8. What is meant by apiculture?
Answer:
Apiculture is bee-keeping, the rearing of honeybees on a large scale to obtain honey and wax.
In simple words: Bee-keeping for honey and wax.

Teacher's Note:
1. Bees also help in pollination of crops.
2. Sericulture is silk worm rearing.

Question 9. What is meant by a sprain?
Answer:
A sprain is an injury in which a ligament at a joint is stretched or torn. It causes pain and swelling. Rest and a cold compress reduce the swelling.
In simple words: A stretched or torn ligament.

Teacher's Note:
1. Ligaments join bone to bone; tendons join muscle to bone.
2. A fracture is a break in the bone, not a sprain.

Question 10. Name the insect which is widely used in genetical studies.
Answer:
The fruit fly, Drosophila. It is cheap to rear, breeds quickly, produces many offspring and has only four pairs of chromosomes, including giant salivary gland chromosomes.
In simple words: Drosophila, the fruit fly.

Teacher's Note:
1. T. H. Morgan used Drosophila in his experiments.
2. Short life cycle makes it ideal for genetic studies.

Question 11. Which element plays an important role in the process of blood clotting?
Answer:
Calcium (Ca²⁺ ions) is required in several steps of blood clotting. Vitamin K is also needed for making clotting factors.
In simple words: Calcium.

Teacher's Note:
1. Without calcium blood does not clot normally.
2. Platelets also help in clotting.

Question 12. What is an electroencephalogram?
Answer:
An electroencephalogram (EEG) is a record of the electrical activity of the brain, taken with electrodes placed on the scalp.
In simple words: A recording of brain waves.

Teacher's Note:
1. An ECG records electrical activity of the heart.
2. EEG is used in the diagnosis of epilepsy.

Question 13. Which polysaccharide is stored in the animal body?
Answer:
Glycogen, stored mainly in the liver and muscles. It is called animal starch.
In simple words: Glycogen.

Teacher's Note:
1. Plants store starch.
2. Glycogen is broken to glucose when energy is needed.

Question 14. Which insect transmits plague from man to man or from rat to man?
Answer:
The rat flea, Xenopsylla cheopis.
In simple words: The rat flea.

Teacher's Note:
1. Plague is caused by the bacterium Yersinia pestis.
2. Controlling rats helps to control plague.

Question 15. Which vitamin is synthesised by the skin in the presence of sunlight?
Answer:
Vitamin D. Ultraviolet rays of sunlight change a substance in the skin into vitamin D, which helps in the absorption of calcium. Its deficiency causes rickets in children.
In simple words: Vitamin D.

Teacher's Note:
1. Sunlight is the natural source of vitamin D.
2. Rickets and osteomalacia are caused by lack of vitamin D.

Question 16. Name the plants which can be compared to amphibians.
Answer:
Bryophytes (mosses and liverworts). They live on land but need water for the male gametes to swim to the egg for fertilisation, just as amphibians need water for breeding.
In simple words: Bryophytes.

Teacher's Note:
1. Pteridophytes have vascular tissue but bryophytes do not.
2. Bryophytes are the amphibians of the plant kingdom.

Question 17. In which organisms do we find an open circulatory system?
Answer:
In arthropods (insects, prawns) and most molluscs. The blood is pumped by the heart into body cavities (sinuses) and flows slowly around the tissues before returning to the heart.
In simple words: Arthropods and some molluscs.

Teacher's Note:
1. In humans blood flows inside vessels: a closed system.
2. An open system gives slower blood flow.

Question 18. Name the cell organelle which is closely associated with protein synthesis.
Answer:
Ribosomes, found free in the cytoplasm or attached to the rough endoplasmic reticulum, make proteins.
In simple words: Ribosomes.

Teacher's Note:
1. Ribosomes are called the protein factories of the cell.
2. Rough ER has ribosomes on it, smooth ER does not.

Question 19. What were the gases found on the earth at the time of its formation?
Answer:
The primitive atmosphere had hydrogen, methane, ammonia, water vapour and some carbon dioxide and nitrogen. There was no free oxygen.
In simple words: A reducing atmosphere without oxygen.

Teacher's Note:
1. Oxygen was added later by photosynthesis of early plants and algae.
2. Miller and Urey tried to make amino acids with such a mixture.

Question 20. Why do you feel hot when you run or do exercise?
Answer:
During exercise, muscles respire faster and use more oxygen. More energy is released and a part of it appears as heat, so body temperature rises, and heartbeat and breathing also quicken.
In simple words: Muscles release more energy and heat when working.

Teacher's Note:
1. Sweating removes the extra heat.
2. Cellular respiration releases energy from food.

Question 21. Name the institute in India that has discovered twenty million year old fossil forests.
Answer:
The Birbal Sahni Institute of Palaeobotany, Lucknow.
In simple words: Birbal Sahni Institute of Palaeobotany.

Teacher's Note:
1. Palaeobotany is the study of fossil plants.
2. Fossils tell us about past life.

Question 22. Where are genes located in a cell?
Answer:
Genes are located on chromosomes in the nucleus, arranged in a line. They are made of DNA.
In simple words: On chromosomes, in the nucleus.

Teacher's Note:
1. Genes carry hereditary information from parents to offspring.
2. Chromosomes are made of DNA and protein.

Question 23. What is demecology?
Answer:
Demecology is the study of populations of a species in relation to their environment. It deals with population size, density, growth and fluctuation.
In simple words: Ecology of populations.

Teacher's Note:
1. Autecology studies a single species and synecology a community.
2. A population is a group of the same species in an area.

Question 24. Why is curd or yoghurt very easy to digest?
Answer:
Lactic acid bacteria ferment milk sugar (lactose) into lactic acid and partly break down proteins. Curd therefore is partly pre-digested, and it also contains useful bacteria that help digestion.
In simple words: Bacteria have already begun to break down milk in curd.

Teacher's Note:
1. Lactobacillus changes milk to curd.
2. People who cannot digest lactose can often take curd.

Question 25. Name two protein deficiency diseases in children.
Answer:
Kwashiorkor and marasmus.
In simple words: Kwashiorkor and marasmus.

Teacher's Note:
1. Kwashiorkor is due to lack of protein, marasmus to lack of both protein and calories.
2. A balanced diet prevents deficiency diseases.