chapter 2

Question 1

during ejactulation how many sperm and released and what happens

Answer 1

200 million to 500 million sperm but only a few hundred complete the 15 to 20 centimetre journey to the fallopian tubes

Question 2

chromosomes

Answer 2

thread like structures in the nucleus of the cell that contain genetic material

Question 3

when an egg and sperm combine at fertilization

Answer 3

the new individual will have the full set of 46 chromosomes, when a sperm penetrates an egg, their chromosomes combine to produce 23 pairs of chromosomes

Question 4

in vitro fertilization (IVF)

Answer 4

involves mixing sperm and egg together in a laboratory dish and then places a few of these fertilized eggs in the mothers uterus

Question 5

autosomes

Answer 5

the first 22 pairs of chromosomes

Question 6

sex chromosomes

Answer 6

the 23rd pair of chromosomes, which determines the sex of the child

Question 7

DNA

Answer 7

a molecule composed of four nucleotide bases, DNA is the biochemical basis of heredity (each chromosomes consists of one molecule of DNA)

Question 8

gene

Answer 8

a group of nucleotide bases that provide a specific set of biochemical instructions

Question 9

genotype

Answer 9

a persons heredity makeup

Question 10

phenotype

Answer 10

the physical, behavioural, and psychological feature that are the result of the interaction between one’s genes and the environment

Question 11

allele

Answer 11

pairs of genes that carry the same traits and are located at the same place on pairs of chromosomes

Question 12

homozygous

Answer 12

containing a pair of the same alleles

Question 13

heterozygous

Answer 13

containing two different alleles

Question 14

dominant allele

Answer 14

expressed whether alone or in pairs, symbolized by a capital letter

Question 15

recessive allele

Answer 15

expressed only in the absence of a dominant allele, symbolized by lowercase

Question 16

incomplete dominance

Answer 16

the situation in which one allele does not dominate another completely

Question 17

sickle cell trait

Answer 17

a disorder in which individuals show signs of mild anemia only when they are seriously deprived of oxygen; occurs in individuals who have one dominant allele for normal blood cells and one recessive sickle cell allele

Question 18

Huntington’s disease

Answer 18

a type of dementia caused by a dominant allele; characterized by degeneration of the nervous system

Question 19

hemophilia

Answer 19

a disorder in which the blood does not clot easily and sufferers can bleed severely from even minor injury (sex-linked)

Question 20

down syndrome

Answer 20

a disorder caused by an extra 21st chromosome, that results in intellectual disability and a distinctive appearance

Question 21

a genetic counsellor constructs a

Answer 21

detailed family history that can be used to decide whether it’s likely that either the man or women carrie’s the allele for the disorder that concerns them

Question 22

behavioural genetics

Answer 22

the branch of genetics that deals with inheritance of behavioural and psychological traits

Question 23

polygenic inheritance

Answer 23

when phenotypes are the result of the combined activity of many separate genes

Question 24

monozygotic twins

Answer 24

twins that result when a single fertilized egg splits to for two new individuals

Question 25

because identical twins come from the same fertilized egg,

Answer 25

they have the same genes that control body structure, height, and facial features

Question 26

dizygotic twins

Answer 26

fraternal twins that are the result of the fertilization of two separate eggs by two sperm

Question 27

clustered regularly interspaced short palindromic repeats (CRISPR)

Answer 27

gene or genome editing has been made possible by the development of this procedure

Question 28

making edits genetically

Answer 28

short sequences of DNA can be cut out of or added to the genome. the procedure allows for specific genetic material to be deleted and replaced by other DNA

Question 29

reaction range

Answer 29

the phenomenon that a particular genotype can interact with various environments to produce a range of phenotypes

Question 30

children’s experiences can

Answer 30

help determine how and when genes are activated

Question 31

epigenesis

Answer 31

the continuous interplay between genes and multiple levels of the environment (from cells to culture) that drives development

Question 32

methylation

Answer 32

a process by which experience changes the expression of DNA, the genetic code is preserved but a gene is silenced by a methyl molecule (genes are “turned off”)

Question 33

heritability coefficient

Answer 33

an estimate of the extent to which differences among people reflect heredity

Question 34

heritability coefficients apply only to

Answer 34

a specific group of people living in a specific environment

Question 35

niche picking

Answer 35

the process of deliberately seeking environments that are compatible with one’s genetic make up

Question 36

example of niche picking

Answer 36

children who are bright (due in part to hereditary) may actively seek peers, adults, and activities that strengthen their intellectual development

Question 37

nonshared environmental influences

Answer 37

forces in the immediate environment (within a family) that make children different from one another

Question 38

many behavioural and psychological phenotypes reflect the combined activity of many genes. in behavioural genetics this is referred to as

Answer 38

polygenic inheritance

Question 39

inherited disorders are usually caused by

Answer 39

recessive alleles

Question 40

results of twin and adoption studies indicate that heredity affects

Answer 40

intelligence, psychological disorders, and personality

Question 41

canalization

Answer 41

used to describe the extent to which genetically determined characteristics are resistance to environmental influences

Question 42

three types of genotype-environment effects

Answer 42

passive effect, evocative effects, active effects

Question 43

passive effects

Answer 43

parents provide genes and environment, effects lessen with age (smart parents create smart environments due to smart genes)

Question 44

evocative effects

Answer 44

child’s characteristics elicit reactions from other, effects constant with age (smart kids due to smart genes evoke smart environments)

Question 45

active effects

Answer 45

child seeks out environments consistent with genotypes, effect increases with age (smart kids due to smart genes seek out smart environments)