Unit 8 Lesson 11: Expressed Traits

Question 1

What is necessary for natural slection to occur

Answer 1

Variation within a population is necessary for natural selection to occur, as it allows for different reproductive success, or genetic fitness, based upon the traits.

Question 2

The variations that can be found from population to population of organisms can be the result of differences in

Answer 2

gene expression

Question 3

Gene expression

Answer 3

Gene expression is when the nucleotides that make up the gene are made into a functional gene unit, such as a protein.

Question 4

Sometimes, though, these variations in expression can be related to environmental factors. Whats that

Answer 4

environmental factor – any living or nonliving factor that influences a living organism

Question 5

distribution

Answer 5

distribution – how the variation in traits is spread across a population

Question 6

One way that scientists can determine if the environment plays a part in the distribution of traits is by comparing the traits of a particular population to the average population traits. Provide an example

Answer 6

For example, scientists were able to discover that sunlight can affect the color of the fish in a population. A population of fish had a higher level of light silver fish compared to dark grey. In the population the scientists studied, there were more dark gray fish because their habitat received a lot of sunlight.

Question 7

Changes in traits can occur due to changes in the chromosomes. Elaborate

Answer 7

Changes in traits can occur due to changes in the chromosomes, such as through crossing-over, when homologous chromosomes swap genetic material during meiosis. When this process occurs, it is not influenced by the environment.

Question 8

Some mutations that create changes in the DNA can influence the variation of a species. Elaborate

Answer 8

For example, scientists can self-pollinate flowers to analyze if variations, such as colors, are a result of the environment or from a change in the DNA. In the purple monkeyflower, also known as Lewis’s monkeyflower, white flowers are produced rather than the typical pink color.
Scientists analyzed the genes for color for gene expression and compared this to the normal population expression. They were able to conclude that a frameshift mutation, not environmental factors, was the cause of the variation in the trait.

Question 9

Explain why variation is necessary in a population.

Answer 9

Variation is necessary in a population as part of natural selection to allow for reproductive success in the population.

Question 10

If there is a correlation between an environmental factor and expression of traits in organisms, does this mean it is a cause for the variation in expression?

Answer 10

No, unless that specific environmental factor and trait are being studied in a controlled lab. If all other factors are taken away and the traits are still experiencing a variation, then it could be determined to have causation. Otherwise, it is just a correlation.

Question 11

The environment can be a factor in the distribution of traits in a population.

Is the statement true or false?

Responses

true

false

Answer 11

True; Environmental factors can affect the traits that are expressed in populations.

Question 12

correlation

Answer 12

correlation – a relationship between two variables but it does not mean that one causes the other

Question 13

causation

Answer 13

causation – the act of producing an end result

Question 14

What are telmeres

Answer 14

Telomeres are the end of the DNA that help protect the DNA.

Question 15

When do telomeres shorten

Answer 15

The telomere tends to shorten as people age.

Question 16

What effects the length of telomeres

Answer 16

Other environmental factors, such as diet and stress, can also affect the length of telomeres.