Genetics and Evolution — 4 Biology PYQs with Answers | UKPSC PYQ Hub

Question 1

The nitrogenous waste-uric acid is excreted out by

Accepted Answer

Birds and Lizards both. The nitrogenous waste uric acid is excreted by birds and lizards both. Birds and reptiles, are most terrestrial arthropods, such as insects are called uricothelic organisms because they convert toxic ammonia to uric acid or the closely-related compound guanine (guano), rather than urea. In contrast, mammals (including humans) produce urea from ammonia. However, they also form some uric acid during the breakdown of nucleic acids. In this case, uric acid is excreted in urine instead of in feces, as is done in birds and reptiles.

Question 2

Which of the following disease is a hereditary disease?

Accepted Answer

Hemophilia. Hemophilia is a hereditary disease, most commonly affecting males, that is characterized by a deficiency in blood clotting. The responsible gene is located on the X chromosome, and since males inherit only one copy of the X chromosome, if that chromosome carries the mutated gene then they will have the disease. Females have a second, usually normal, copy of the gene on their other X chromosome, so they are capable of passing on the disease without experiencing its symptoms.

Question 3

In Genetic engineering the latest technique developed is?

Accepted Answer

Gene mapping. Gene splicing, a core genetic engineering technique, allows the cutting and recombining of DNA. It enables scientist to modify organism's genes with advance methods like CRISPR making it more precise and effective. a 39. Two bacteria found to be very useful in genetic engineering experiments are ........ (a) Nitrosomonas and Kliebsiella (b) Escherichia coli and Agrobacterium (c) Nitrobacter and Azotobacter (d) Rhizobium and Diplococcus

Question 4

A marriage is solemnized between colour blind male with a normal female whose parents eye- sight was also normal. Then what percentage of children born will have the probability of being colour blind?

Accepted Answer

50%. Colour blindness is specifically linked to defects within the X chromosome. For colour blindness to be present all ‘X’ chromosomes within an individual have to be affected, and since men only have one X chromosome and women have two the chances of men being impacted are exponentially higher. However, in this case, it would seem that due to the genetic inheritance of the mother the chances of their child being colour blind would be approximately 50% because each parent is a carrier. However, the chances of inheriting a colour blind X chromosome would be twice as likely for a female child. Below is how this scenario breaks down, where the lower case x represents the affected X chromosome. M: xY (male) F: xX (Female) xx—-Female child (colour blind) xX—Female Child (not colour blind but a carrier) Yx—Male Child (Colour Blind) YX—Male Child (not colour blind and not a carrier) So, the correct answer is '50%'. Classification of Living