Q.2 Tick the correct answer. (a) Yeast is used in the production of
(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen
(b) The following is an antibiotic
(i) Sodium bicarbonate (ii) Streptomycin (iii) Alcohol (iv) Yeast
(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito (ii) cockroach (iii) housefly (iv) butterfly
(d) The most common carrier of communicable diseases is
(i) ant (ii) housefly (iii) dragonfly (iv) spider
(e) The bread or idli dough rises because of
(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading
(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection

a) (ii) alcohol
b) (ii) Streptomycin
c) (i) female Anopheles mosquito
d) (ii) housefly
e) (iii) growth of yeast cells
f) (iii) fermentation

EXPLANATION:-

a) Yeast is a microorganism, made up of just a single cell. Yeast cells grow through a process called budding in which a small yeast cell grows on the outside of a mature one, until it is fully grown and ready to separate. The primary role of yeast is to convert glucose into ethanol and carbondioxide. Ethanol is released by the yeast cells as a waste product.

b) Streptomycin is an antibiotic medication used to treat a number of bacterial infections. This includes tuberculosis, Mycobacterium avium complex, plague, rat bite fever etc. Dosage is based on the kind of infection, weight of the infected individual, medical condition of the individual, streptomycin blood levels, and the side effects.

c) Malaria is transmitted to humans by female mosquitoes of the genus Anopheles. Thus female Anopheles mosquito acts as the malaria vector. Female mosquitoes take blood for their egg production.

d) House flies can spread diseases such as food poisoning and dysentery. They contaminate food and surfaces by defecating on them.

e) Yeast cells grow through a process called budding in which a small yeast cell grows on the outside of a mature one, until it is fully grown and ready to separate.

f) The process of conversion of sugar into alcohol is called fermentation. This fermentation is carried out by the yeast.