Got Lactase?

What two monosaccharides (simple sugars) are formed when lactase enzyme hydrolyzes lactose?

• Glucose and fructose

• Glucose and galactose

• Galactose and maltose

• Glucose and maltose

Geneticists studying the gene for lactase did not find any differences in the coding region DNA (the sequence with instructions to make the protein) between people who could digest lactose and people who could not digest lactose. After they investigated further, they discovered that the difference between lactose tolerant and intolerant individuals was due to a mutation located in

• the genetic switch for the lactase gene

• the gene for glucose production

• an intron of the lactase gene

• different genes for different individuals

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NGSS.HS-LS3-1

Which statement accurately describes human evolution?

• Human evolution ended 200,000 years ago when humans (Homo sapiens) became a distinct species.

• Humans continued to evolve until the species adapted to a pastoralist way of life and then stopped evolving.

• Humans are still evolving and will continue to evolve through natural selection.

• Human evolution through natural selection ended with the advent of modern medicine

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Which discovery supports the hypothesis that evolution of the lactase persistence trait was driven by the use of milk in pastoralist cultures?

• The lactase gene is present both in humans and in domesticated animals

• Ancient pots used to hold milk are about the same age as the lactase persistence mutations.

• Most human cultures today drink milk and most people worldwide are lactase persistent.

• Scientists have identified different mutations that cause lactase persistence.

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Why would measuring blood glucose levels in an individual, 20 to 30 minutes after they drink a liter of milk, indicate whether they are able to digest lactose

• When lactose is digested by lactase in the small intestine, different cells in the body start releasing glucose into the bloodstream

• When lactose is digested by lactase, the glucose that is produced enters the bloodstream from the small intestine

• When lactose enters the large intestine, glucose is digested by bacteria and then enters the bloodstream

• The fats and proteins in milk are digested by the body, causing glucose levels in the blood to increase.

What would be the effect of a mutation in the coding region of the lactase gene?

• The lactase enzyme could have a different structure

• The lactase enzyme could have a different function

• The individual might not be able to digest lactose as an infant or as an adult

• All of the choices are correct

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Why could milk have provided strong favorable selection for lactase persistence?

• People who can digest milk can obtain calories during times when little other food was available

• Being lactase persistent guarantees that an individual will survive and reproduce

• Ancient humans could eat McFlurrys and Dairy Queen

• Lactose intolerant individuals were probably kicked out of their tribes because they got gas from drinking milk

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The majority of people worldwide are lactose intolerant

• True

• False

Select all of the sugars

• Glucose

• Galactose

• Lactose

• Lactase

A protein that speeds up chemical reactions is

• an enzyme

• a simple sugar

• a complex carbohydrate

• DNA