Modern Human Variation Questions and Answers

Answer: D

The immediate response to exposure to a cold environment is vasoconstriction, the narrowing of the blood vessels of the skin and extremities. It reduces blood flow to the surface and so cuts heat loss from the body core within seconds of the exposure.

Thermogenesis (shivering and non-shivering heat production) is a later, supplementary response. Vasodilation is the heat-dumping response to warm conditions. Homeostasis is the general name for keeping the internal state steady, not a specific response to cold.

Answer: A

'Human Heredity' is a book by Ashley Montagu, the anthropologist known for work on race and human biology. Of the authors named, only he wrote this title.

R.H. Lowie is known for 'Primitive Society', E.A. Hoebel for 'The Law of Primitive Man', and A.M. Brues for 'People and Races', so none of them fits.

Montagu's other well-known works include 'Man's Most Dangerous Myth: The Fallacy of Race' and 'The Natural Superiority of Women', which show the same interest in biology and society that makes 'Human Heredity' his book.

Answer: D

Both statements are correct. Goitre, an enlargement of the thyroid gland, is common among populations of the Himalayan region, where soil and water are poor in iodine. The reason is also true, since goitre is caused chiefly by iodine deficiency, which leads to a deficiency of thyroid hormone and an enlarged gland.

The other options call one or both false, and so are wrong.

Iodine is a part of thyroxine, so where the diet lacks it the pituitary keeps stimulating the thyroid and the gland swells. Mountain regions far from the sea, with leached soils, are classic goitre belts, which explains why Himalayan groups are affected.

Answer: D

The correct matches are a-ii, b-iii, c-iv, d-i. Haemoglobin S (sickle cell) is common in Africa; Hb E is common in South-East Asia; thalassaemia is found around the Mediterranean, including Greece; migration is a microevolutionary force, together with mutation, selection, drift and gene flow. The code is ii iii iv i, option D.

Options A, B and C pair Hb S with the force or with Greece, or put Hb E in Africa.

Sickle cell, Hb E and thalassaemia are balanced polymorphisms linked to malaria resistance, so each is common where malaria was or is common, and that is why they are tied to regions in the list.

Answer: D

The correct matches are a-iv, b-iii, c-ii, d-i. The main line formula (for example 11.9.7.) records where the palmar main lines end; the hypothenar is an area of the palm; the angle atd is measured at the triradius of the palm; and the pattern type (loop, whorl, arch) is a finger pattern. The code is iv iii ii i, option D.

Options A, B and C pair the main line formula with the finger or the triradius, or pair the pattern type with the palm.

Answer: D

The correct matches are a-ii, b-iv, c-i, d-iii. Blood group A has the genotypes AA or AO, group B has BB or BO, group O is OO, and group AB is AB. The code is ii iv i iii, option D.

Options A and B pair group A with OO, which is group O. Option C gives group B the OO genotype, so it is wrong too.

Remember that the ABO blood groups are the phenotypes, the visible result that is tested with antisera, while the genotypes are the allele pairs behind them. A and B are dominant over O, so group A can be AA or AO and group B can be BB or BO, whereas O needs two O alleles and AB shows both A and B.

Answer: C

The correct matches are a-iii, b-iv, c-ii, d-i. The occipital bone is part of the cranium (cranial part), the maxilla is a facial bone, the tibia is a bone of the lower limb, and the radius is a bone of the forearm. The code is iii iv ii i, option C.

Options A and B put the occipital bone in the lower limb, and option D calls it a facial bone and makes the radius part of the cranium; each fails at least two pairs.

Check each pair against the skeleton: the skull holds the cranial bones (occipital, frontal, parietal, temporal) and the facial bones (maxilla, mandible, zygomatic), and the limbs hold the long bones: radius and ulna in the forearm, femur, tibia and fibula in the leg.

Answer: A

Furuhata's index is whorls divided by loops, multiplied by 100.

In dermatoglyphics, Furuhata's index expresses the ratio of whorls to loops on the fingertips as a percentage, and it is used to compare populations.

Arches divided by whorls, multiplied by 100, is the Dankmeijer index, a different ratio. Two times whorls plus loops divided by N, the number of digits, is the pattern intensity index. So only the first option is Furuhata's index.

Answer: D

A normal distribution shows that most individuals lie near the average and few at the extremes, so the answer is Both (B) and (C).

In the bell-shaped curve for a continuous trait, the largest number of individuals is close to the mean, and the number falls off steadily towards each extreme, so fewer individuals have the extreme genotype.

Option A, that all individuals are homozygous for the trait, is wrong, because a normal distribution of a polygenic trait comes from variation in genotypes.

Answer: B

The term genetics was introduced by W. Bateson.

William Bateson proposed the word in a letter of 1905 and used it publicly at a conference in 1906, for the science of heredity and variation. He was also one of those who brought Mendel's work to wide attention in Britain.

A. Marshall, J. F. Crow and D. Falconer are not credited with coining the term. Crow and Falconer are known for population and quantitative genetics, and they worked much later than Bateson, so they could not have introduced it.