521: Corpus luteum is a mass of cells found in
(a) brain
(b) ovary
(c) pancreas
(d) spleen
522: Which one of the following organisms is likely to show the highest- concentration of DDT once it has been introduced into the ecosystem ?
(a) Grasshopper
(b) Toad
(c) Snake
(d) Cattle
Explanation:
The increased levels of DDT's concentration from one trophic level to other in the food chain is called Biomagnification. 'Snakes' shows the highest concentration of DDT because they are tertiary consumers. Grasshoppers and Cattle occur in the same trophic level as primary consumers, so DDT's concentration is least. Toad is secondary consumer and shows medium concentration of DDT.
523: Which of the following is / are the characteristic / characteristics of Indian coal?
1. High ash content
2. Low sulphur content
3. Low ash fusion temperature
Select the correct answer using the codes given below.
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3
Explanation:
Indian coals are high in ash content but low in sulphur content. Indian coal has very high ash fusion temperature of about 1,500 degree celcius.
So statement 1 and 2 are correct and third is wrong.
524: Alpha-keratin is a protein present in
(a) blood
(b) skin
(c) wool
(d) eggs
Explanation:
Alpha-keratin, a secondary structural protein is present in 'wool and hair' while Beta-keratin in 'nail and hoof'.
525: Pyrilla is a
(a) Disease of teeth and gums
(b) An insect pest
(c) A character of ancient Greek mythology
(d) A building heated by solar energy