1. How do children in many parts of India get immune to hepatitis A by the time they are 5 years old? 
Ans. The vaccine of hepatitis A is given to the children below 5 years of age to produce immunity against hepatitis A.
2. (a) A flowering plant whose embryo possesses single cotyledon (Give scientific term). (b) A unicellular, eukaryotic aquatic organism (Name the kingdom) 
Ans. (a) Monocotyledonous plants (seeds with one cotyledon) (b) kingdom Protista
3. Why are we normally advised to take bland and nourishing food when we are sick?
Ans. When we are sick, our normal body functioning is disturbed. During that period, if we take bland and nourshing food, it helps in digestion and absorption by the body.
4. Why are antibiotics effective against bacteria but not against viruses? 
Ans. Antibiotics are effective against living organism like bacteria while the viruses are DNA fragments, not a living organism. Hence, viruses cannot be killed by any antibiotic.
5. (a) Give one characteristic difference between primitive and advanced organisms. (b) Name the phylum to which the following are included. (i) Spider (ii) Cockroach (iii) Prawn (iv) Housefly
Ans: (a) The activities of life are performed by a single cell in primitive organisms while there are different organs for performing various functions in advanced organisms.
(b) (i) Spider – Arachnida (ii) Cockroach – Dictyoptera (iii) Prawn – Arthropoda (iv) Housefly – Arthropoda
6. List three ways to control soil pollution. 
Ans. (i) Proper drainage and sewer system in densely populated areas, so that they do not go in open for defaecation.
(ii) Less use of chemicals in the form of fertilizers, pesticides, weedicides, etc.
(iii)Proper disposal of non-degradable waste materials such as plastic carry bags, glass bottles, electronic wastes, etc.
7. "The flow of energy is unidirectional whereas the biogeochemical transfer is cyclic". Explain why?
Ans: Energy transfer is said to be unidirectional because when the energy is absorbed by autotrophs from the sun, it is never reabsorbed by it. Similarly when consumers eat up the producers directly or indirectly the energy transferred in this process can never be reversed in the food chain. On the other hand in biogeochemical cycles are those through which chemical elements move from environment to organism and back to the environment. Hence, they are never lost.
8. Give cause and remedy of : (a) Hepatitis (b) AIDS (c) Malaria 
Ans. (a) Hepatitis : It is a serious disease caused by hepatitis virus.
Vaccines for Hepatitis A and Hepatitis B should be taken.
(b) AIDS — It is caused by a virus (HIV), Human Immunodeficiency Virus.
Avoid the transfer of HIV positive blood .
(c) Malaria — It is spread by female Anopheles mosquito
Quinine is a medicine for malaria treatment. It is obtained from a tree.
9. (i) Make neat and labelled sketch of Nitrogen cycle in nature.
(ii) Describe in brief the role of Nitrogen fixing bacteria and of lightening in fixing atmospheric nitrogen.
Ans: Make neat and labelled sketch of Nitrogen cycle in nature.
Certain bacteria and blue-green algae can fix atmospheric nitrogen directly into nitrates.
The nitrogen-fixing bacteria can be free-living, like Azotobacter and Clostridium, or symbiotic bacteria (Rhizobium). Rhizobium is found in the root nodules of certain leguminous plants, like peas and beans
10. What is immunization? Name any four diseases which can be prevented by immunization. 
Ans. Immunisation is a specific method for preventing diseases. Immunisation protects the body by either helping it to create new antibodies by presenting part or whole of the disease–causing agent to the person's immune system, a long term approach or by providing it with active antibodies, a temporary solution.
Polio, tuberculosis, measles, tetanus, etc. are the diseases which can be prevented by immunization.
Searches related to solved sample paper of 9th class
sample paper of science class 9th Click Here
Solve Sample paper [ 9th Biology] Download /View