IGCSE Biology Paper-2: Specimen Questions with Answers 198 - 199 of 203
Question 198
Question
MCQ▾Which combination of sex chromosomes in the sperm and the egg will produce a male child?
Choices
| Choice (4) | |
|---|---|
a. | sex chromosome in sperm-Y, sex chromosome in egg-X |
b. | sex chromosome in sperm-X, sex chromosome in egg-X |
c. | sex chromosome in sperm-X, sex chromosome in egg-Y |
d. | sex chromosome in sperm-Y, sex chromosome in egg-Y |
Answer
a.Explanation
- The sex chromosomes are also known as Allosomes or heterosomes. In females, the sex chromosomes are XX and in males, they are XY.
- The Y chromosome in human determines the maleness. It carries a gene ‘Sry’ (sex determining region of Y-chromosome) which codes for a product called TDF (Testis determining factor) . TDF is required for the development of male sex and its absence leads to the femaleness.
Question 199
Question
MCQ▾Why is yeast used in bread making?
Choices
| Choice (4) | |
|---|---|
a. | Aerobic respiration produces alcohol. |
b. | Aerobic respiration produces lactic acid. |
c. | Anaerobic respiration produces carbon dioxide. |
d. | Anaerobic respiration produces alcohol. |
Answer
c.Explanation
- Bread is fermented using Baker՚s yeast (Saccharomyces cerevisiae) . “Saccharomyces Cerevisiae” used for bread making commonly called as brewer՚s yeast is also used for fermenting malted cereals and fruit juices to produce ethanol.
- Depending on the type of raw material used for fermenting & type of processing, different types of alcoholic drinks are obtained.
