Ch 3: Genes, Environment, and Development

Question 1

Natural Selection

Answer 1

Involves the notion that some genes aid in adaptation more than other genes do, and thus are more likely to be passed on in future generations.

Question 2

Conception

Answer 2

Defined as the (magic) moment when the egg is fertilized by the sperm.

Question 3

At conception the _____ material of the mom’s ____ (egg) & Dad’s sperm unite to form a _____.

Answer 3

Genetic, ovum, zygote.

Question 4

Chromosomes

Answer 4

Consist of thousands of genes. Scientists estimate the average human cell contains 20-2500 genes.

Question 5

Identical Twins

Answer 5

Occur when a fertilized ovum (egg) divides to form 2 separate individual cells. (1 in 250 births)

Question 6

Fraternal Twins (“dizygotic”)

Answer 6

Involve any 2 individual ova being released and each of the two is fertilized by different sperm cells. (1 in 125 births)

Question 7

Identical twins share 100% of genes, therefore any differences between them must be due to ________.

Answer 7

Environment (pre- and post-natal).

i.e. 48% chance both twins get schizophrenia.

Question 8

Fraternal twins share ABOUT __% of genes.

Answer 8

50%.

On average, this is true about biological siblings born years apart.

Question 9

The __ chromosome is stubbier and has more genes than the __ chromosome.

Answer 9

X, Y.

X about 11000 genes and Y about 80

Question 10

Genetic Expression

Answer 10

Involves the ACTIVATION of particular genes in particular cells, at particular times. Genetic expression may be linked to environmental events, so that environmental occurrences may turn genes on or off.

Question 11

Polygenic Inheritance

Answer 11

The result of several genes in a combination, interacting with one another in environmental triggers. Causes most behavior and personality traits as well as mental illnesses.

Question 12

Phenotype & Genotype

Answer 12

Genotype: inherited genes (like genes on the X chromosome).
Phenotype: Involves overt expression of genes/genetic influence (like having blue eyes)

Question 13

Recessive Traits

Answer 13

Matching pair of genes needed to express (overtly show) a characteristic carried by a pair of genes. (2 recessive needed for trait to show).

Question 14

Incomplete Dominance

Answer 14

When there is a compromise between the effect of 2 genes (blending of two traits).

Question 15

Co-dominance

Answer 15

2 characteristic coexist.

Question 16

The Period of the Zygote begins with ______. A developing human traveling through the fallopian tube to the uterus.

Answer 16

Fertilization.

Question 17

Tina is in her 5th week of pregnancy. She is carrying an ____.

Answer 17

Embryo.

Question 18

Embryo

Answer 18

When a developing child has just become completely embedded in the wall of the uterus, about 2 weeks into the pregnancy. Lasts week 3 to 8.

Question 19

Is hemophilia most frequently passed onto the male or female offspring?

Answer 19

Male.

Question 20

Genetic Mutation

Answer 20

Involves some sudden change in the gene structure, that was not passed on by the parents.
i.e. exposure to significant radiation may result in mutation.

Question 21

All major organs completely develop in some fashion during the _____ period of pregnancy.

Answer 21

Embryonic.

Formation of primitive heart, sex organs, eyes and nose take shape but ears come in much later.

Question 22

__% of recognized pregnancies miscarry.

__% of un-recognized pregnancies miscarry.

Answer 22

20%, 50%.

Question 23

Main function of the Amnion:

Answer 23

To provide a protective cushion for the developing embryo. Protects against bumps etc.

Question 24

Main purpose of the Placenta:

Answer 24

Provide oxygen and nutrients to the fetus, while removing CO2.

Question 25

What is the third stage of pregnancy?

Answer 25

The Fetus, week 9-birth.

Question 26

How is a developing child known to be a fetus?

Answer 26

Known when there are 3 things:

1) Contractions can occur & the cervix can open or dilate
2) Crowning- baby’s head appears and is pushed out of vagina.
3) Placenta/after bith is expelled.

Question 27

Extra 21st chromosome causes and odds:

Answer 27

Down Syndrome. From either mom or dad (tirisomy 21).
Odds of having baby with Down Syndrome: 
Age 20-24: 1 in 1400
Age 24-29: 1 in 1100
Age 25: 1 in 350
Age 40: 1 in 100
Age 45: 1 in 25

Question 28

The odds of having a child with Down Syndrome _____ with maternal age, because the rate of having children decreases with age.

Answer 28

Increase.

Question 29

Huntington’s Disease

Answer 29

An unusual genetic disorder because the genetic impact does not occur until a person reaches middle age.

Question 30

Identical twins raised ______ score more similarly on IQ tests than fraternal twins raised ______. Therefore there is a strong genetic influence on development of such traits.

Answer 30

apart, together.

Question 31

If GENES alone contribute to a trait, what pattern would be seen (%)?
If shared ENVIRONMENT alone what pattern would be seen?

Answer 31

1. 00 for identical twins reared apart.
2. 50 for fraternal twins raised together.

No correlation for those reared apart.
1.00 for identical and fraternal raised together

Question 32

As we get older, genetic influences on intelligence _____, and environmental influences ______. However, shared environmental influences are ______ in importance.

Answer 32

Increase.
also increase.
Decreasing.

Question 33

When 1 to both parents have schizophrenia, the odd of their children having it are greater than the average risk, in response to an environmental factor, such as an infant contracting a virus. This is an example of ______.

Answer 33

Gene-environment Interaction

Question 34

In terms of identical twins raised apart, research shows that some of their traits are more influenced by genes than other traits. In order from highest to lowest the most influenced traits are:

Answer 34

1. Height (most)
2. Brain activity
3. IQ scores
4. Creativity

Question 35

Depression & Genes: some genes actually ______ a person from depression, while other genes ______ a person to depression.

Answer 35

Protect.

Predisopose.

Question 36

Active Gene-Environment Interaction

Answer 36

A person’s genes make it more likely he or she will seek out certain activities.
i.e. a child predisposed to be good at music actively pushes parents to get the family a piano and lessons for him.