Which of the following are not the effects of
Parathyroid hormone?
A.Stimulates the process of bone resorption
B.Decreases Ca2+ level in blood
C.Reabsorption of Ca2+ by renal tubules
D.Decreases the absorption of Ca2+ from digested food
E.Increases metabolism of carbohydrates
Choose the most appropriate answer from the
options given below:
If a colour blind female marries a man whose
mother was also colour blind, what are the chances
of her progeny having colour blindness?
Explanation:
Color blindness is an X-linked recessive trait. A color-blind female has genotype XbXb. If she marries a color-blind man (mother color-blind makes him XbY), their children will inherit Xb from the father and Xb from the mother for daughters (XbXb) and Xb from the mother with Y from the father for sons (XbY). Thus all offspring will be color blind. Therefore the chances are 100% (option 3).
🧠 Did You Know?
NCERT states that color blindness is an X-linked recessive trait, so it is passed through X chromosomes and often affects males more commonly.
💡 NCERT Memory Line:
Color blindness is an X-linked recessive trait; a color-blind female (XbXb) crossed with a color-blind male (XbY) yields color-blind offspring of all sexes.
Ten E.coli cells with 15N- dsDNA are incubated in medium containing 14N nucleotide. After 60 minutes, how many E.coli cells will have DNA totally
free from 15N ?
Explanation:
Start with 10 E.coli cells containing 15N- dsDNA. In 14N medium, DNA replication produces one old strand and one new strand per chromosome. After each generation, the proportion of 14N-only DNA increases. After 1st generation (≈20 min): all cells are hybrid (15N-14N). After 2nd generation: 1 cell becomes 14N-14N (light) and 1 remains hybrid per two cells, so 50% light. After 3rd generation: light cells produce two light, and hybrid cells produce one light and one hybrid, giving 3 light and 1 hybrid among 4 cells. With 10 initial cells, total cells after 3 generations = 80; light (14N-only) cells = 3/4 of 80 = 60. So 60 cells are totally free from 15N.
🧠 Did You Know?
This follows the Meselson–Stahl experiment logic used in NCERT to show semi-conservative DNA replication and the appearance of light (14N) and hybrid (15N-14N) DNA generations in a 14N medium.
💡 NCERT Memory Line:
In 14N medium, after n generations, the fraction of 14N-only DNA is (1/2)^(n-1) for the first half? Actually, cumulative: after 3 generations, 3/4 of cells are 14N-only.
The recombination frequency between the genes a &
c is 5%, b & c is 15%, b & d is 9%, a & b is 20%, c & d is 24% and a & d is 29%.
What will be the sequence of these genes on a linear chromosome ?
Explanation:
In a linear chromosome, the recombination frequencies reflect the distance between adjacent genes. The order a–c–b–d gives: a–c = 5%, c–b = 15%, b–d = 9%. Then a–d = 5 + 15 + 9 = 29%, c–d = 15 + 9 = 24%, and a–b = 5 + 15 = 20%, all matching the given data. Hence the correct gene sequence is a, c, b, d. Options that place the genes in different adjacent arrangements do not fit all the given recombination frequencies. For example, option 2 (a, b, c, d) would not produce a–c = 5% and c–d = 24% simultaneously, etc.
🧠 Did You Know?
Recombination frequency is used to map genes on a chromosome in map units (mu); 1% recombination equals 1 mu, a key NCERT concept in genetic mapping.
💡 NCERT Memory Line:
Order the genes so that all pairwise distances add up to the given figures; the adjacent distances must sum to the total distances for non-adjacent pairs.
Statements related to human Insulin are given below.
Which statement(s) is/ are correct about genetically engineered Insulin?
A. Pro-hormone insulin contain extra stretch of
C-peptide
B. A-peptide and B-peptide chains of insulin were
produced separately in E.coli, extracted and
combined by creating disulphide bond between
them.
C. Insulin used for treating Diabetes was extracted from Cattles and Pigs.
D. Pro-hormone Insulin needs to be processed for converting into a mature and functional hormone.
E. Some patients develop allergic reactions to the foreign insulin.
Choose the most appropriate answer from the
options given below:
Given below are two statements: Statement I: In a scrubber the exhaust from the thermal plant is passed through the electric wires to charge the dust particles. Statement II: Particulate matter (PM 2.5) can not be removed by scrubber but can be removed by an electrostatic precipitator.
In the light of the above statements, choose the
most appropriate answer from the options given
below:
