Fresno State BIO 10 Homework 9: Lactose Intolerance

Suppose that a mutation for lactase persistence occurred in each of the pastoral populations described below. In which population would the mutation be more likely to increase in frequency over time due to natural selection?

a. A population that raises wheat and sheep. b. A population that raises potatoes and chickens. c. A population that raises rice and tilapia fish. d. A population that raises corn and beans. correct answer: a, A population that raises wheat and sheep.

The primary sugar in milk is lactose. The enzyme lactase breaks lactose down into which compound(s)?

glucose fructose sucrose galactose Correct answer(s): glucose, galactose

Which individuals show evidence of lactase persistence?

Spencer Wells Peter Rachel Katherine Sarah Michael Arthur Correct Answers: Spencer Wells, Peter, Sarah, and Michael

Which discovery best supports the hypothesis that evolution of the lactase-persistence trait was driven by dairying, the use of milk as a source of adult nutrition in pastoralist cultures?

a. Ancient pots used to hold milk are about the same age as the lactase-persistence mutations. b. The lactase gene is present in both humans and domesticated animals. c. Present-day milk fats and animal body fats can be distinguished using carbon isotope analysis and gas chromatography. d. Scientists have discovered different mutations for lactase persistence in different cultures. correct answer: a. Ancient pots used to hold milk are about the same age as the lactase-persistence mutations

Four individuals measured their baseline blood glucose, then quickly drank a liter of milk. They then measured their blood glucose levels at regular 15 minute intervals for 60 minutes. The results are shown in the graph. Which individual or individuals are lactase persistent, and how do you know?

a. Arthur, because his glucose level goes down. b. Rachel, because her glucose level returns to her baseline level. c. Peter and Sarah, because their glucose levels increase dramatically after drinking milk. d. Peter, Rachel, and Sarah, because their glucose levels went up after drinking milk. Correct Answer: c. Peter and Sarah, because their glucose levels increase dramatically after drinking milk.

A person taking a glucose test is usually told to fast prior to the test. Why would fasting be necessary?

a. Galactase in the blood could impact the test results. b. Many types of foods are digested into glucose which would influence the test results by decreasing the amount of lactase in the blood. c. Many types of foods are digested into glucose which would influence the test results by not providing an accurate baseline level. d. So they are hungry enough to drink a liter of milk. correct answer: c, Many types of foods are digested into glucose which would influence the test results by not providing an accurate baseline level.

How could milk drinking have provided strong favorable selection for lactase persistence? Select all that apply.

a. Milk could have been a critical food source during times of famine. b. Milk is generally safer to drink than water. c. Milk is rich in proteins and fats. d. Milk could have been given to babies as a source of nutrition. correct answer(s): a,b,c

How would a biologist describe someone who is "lactose persistent"?

a. Someone who is able to digest and tolerate lactose as a child, but who loses the ability as an adult. b. Someone who is able to digest lactose as an adult. c. Someone who is unable to digest and tolerate lactose as an adult. d. Someone who is unable to digest and tolerate lactose as a child. correct answer: b, someone who is able to digest lactose as an adult

What did researchers discover about genetic mutations that cause lactase persistence?

a. They are found in the part of the DNA that encodes lactase "the lactase gene". b. They are found in a noncoding regulatory region (a "switch") near the lactase gene. c. The mutations that cause lactase persistence in European and African populations are identical. d. The mutations that cause lactase persistence in European and African populations affect different genes. correct answer: b, They are found in a noncoding regulatory region (a "switch") near the lactase gene.

It would be expected that the Maasai people of Kenya would be lactase persistent.

a. true b. false correct answer: a, true