Question

1. You meet a woman who is heterozygous for an X-linked dominant disorder. Who did this woman inherit this disorder from?

Select one:

a. Both her mother and her father

b. Her mother

c. Either her mother or her father

d. Her father

e. It is not possible to determine without more information.

2. If a photosynthetic organism is supplied with water (H₂O) containing a heavy isotope of oxygen (¹⁸O)—H₂¹⁸O, which can be readily distinguished from ‘normal’ water (H₂¹⁶O)—predict the product(s) of photosynthesis that contain(s) the ¹⁸O?

Select one:

a. More than one of the above answer options is correct.

b. Water (H₂O)

c. Molecular oxygen (O₂)

d. Carbohydrates, like glucose (C₆H₁₂O₆)

e. None of the other answer options are correct.

Answer 1

1) females have 2 X chromosomes, one from father and other from mother, and males inherit X chromosome from mother only.

let`s show this using punnet square

female is XX and male is XY

let`s use Xm to indicate maternal X chromosome and Xp to indicate paternal X chromosome.

XmXm * XpY

	Xm	Xm
Xp	XmXp	XmXp
Y	XmY	XmY

so females are XmXp, that is females inherit X chromosome from both father and mother.

The female is affected with sex-linked dominant trait and she is heterozygous so she could have inherited the dominant allele from either father or mother so the answer is c) Either her mother or her father.

2) water undergoes photolysis,

H2O2H+ + 1/2O2+ 2e-

water is split into H+, electrons, and oxygen by the water-splitting complex associated to the Photosystem II, electrons from the water replace the electron lost from the PSII via excitation by the photons, so the answer is c) Molecular oxygen (O2)