Question

1. Among the following organisms, which organisms have sex chromosomes (XY)?

A. lizard and alligator

B. tortoise and turtle

C. anemone fish

D. flies and humans

E. all of the above

2. Among the following genes, which gene detects the ratio of autosomes to X chromosomes in flies?

A. Sry

B. Sxl

C. Tra

D. Dsx-M

E. Dsx-F

(Q3-6) The following are the various karyotypes we can observe among the organisms with the XY sex determination system.

a. XY​​b. XX​​c. XO​​d. XXX​​e. XXY​​f. XYY

3. Which karyotypes are all females in flies?

A. b, c, e,

B. b, e, f

C. b, d, e,

D. b, c, f,

E. a, c, f,

4. Which karyotypes are all males in flies?

A. b, c, e,

B. b, e, f

C. b, d, e,

D. b, c, f,

E. a, c, f,

5. Which karyotypes become opposite sexes between flies and humans?

A. a, c

B. b, c

C. c, d

D. c, e

E. c, f

6. Which karyotypes will show at least one Barr body?

A. b, d, e

B. a, b, d

C. b, d, f

D. a, d, e

E. b, c, e

Answer 1

1. The correct answer is D. Flies and humans have XY sex chromosomes.

• Option A is incorrect as lizards don't have morphologically distinguishable sex chromosomes. Alligators also don't have a heteromorphic sex chromosome and the sex is determined by the incubation temperature of the egg during embryonic development.
• Option B is incorrect. Turtles demonstrate the genotypic and temperature-dependent sex-determining mechanism.
• Option C is incorrect. Anemone fish male has ZZ chromosome, females represent the presence of the WZ chromosome.