exam 3

Question 1

how many pairs of chromosomes are there

Answer 1

23 pairs

Question 2

what is a genotype

Answer 2

our DNA

Question 3

what is the difference between a heterozygous genotype and a homozygous genotype

Answer 3

heterozygous genotype: copies are different alleles

homozygous genotype: both copies are the same allele

Question 4

what is a phenotype

Answer 4

our observable characteristics or traits

Question 5

what affects your phenotype

Answer 5

our genes, environment, and chance define your phenotype

Question 6

what does it mean to say a trait is dominant or recessive

Answer 6

dominant- shown when a person only has one copy of that gene
recessive- when two copies of that gene is present

Question 7

what are the genotype and phenotype of someone who is a carrier

Answer 7

the trait is only shown on the recessive gene

ex: Aa

Question 8

what is incomplete dominance

Answer 8

phenotype of the heterozygote is intermediate between the two homozygotes Cs = wavy hair (CC =curly and ss = straight)

Question 9

how does meiosis halve the number of chromosomes per cell

Answer 9

lines them up along the midline and then pulls them apart into two separate cells

Question 10

what is the difference between autosomes and sex chromosomes

Answer 10

22 pairs of autosomes and 1 pair of sex chromosomes

Question 11

male genotype

Answer 11

X Y

Question 12

what is the location and function of the SRY gene

Answer 12

located on the Y chromosome, has instructions for making,ing a regular protein, signals for gonads to develop into testes

Question 13

what is a sex-linked trait

Answer 13

located on either the X or Y chromosome

Question 14

how can you use a Punnet square to predict the probabilities of X-linked phenotypes for children given the genotypes of the parents

Answer 14

you can match the two genotypes of each parent to make a percentage of their chances to get certain traits

Question 15

what are the symbols used in pedigrees

Answer 15

X Y

Question 16

why is a genotype not necessarily sufficient to predict phenotype

Answer 16

because phenotype is based on genes environment and chance

Question 17

what error in meiosis can change the number of chromosomes in a cell

Answer 17

the failure of chromosomes to separate during meiosis

Question 18

how does the number of chromosomes in a cell relate to Down syndrome

Answer 18

they have extra or less chromosomes

Question 19

what is a gene pool

Answer 19

collection of all of the alleles in a population

Question 20

what is a population

Answer 20

a group of organisms in a geographic area

Question 21

what is genetic drift

Answer 21

random changes in the allele frequencies of a population between generations

Question 22

what are two major mechanisms of genetic drift

Answer 22

the founder effect, the bottleneck effect

Question 23

how does natural selection result in adaptation

Answer 23

differential survival and reproduction of individuals within a population in response to environmental pressure

Question 24

what is necessary for natural selection to occur

Answer 24

individuals within a population vary, some variants have more offspring

Question 25

what is fitness and how does it relate to natural selection

Answer 25

organisms ability to survive and reproduce in a particular environment, higher fitness = increased likelihood of alleles being passed to the next generation

Question 26

female genotype

Answer 26

X X

Question 27

when did life first appear on earth and what type of life was it

Answer 27

first were prokaryotes 3.7 by a

Question 28

what is the order of events for the history of life on Earth

Answer 28

3.7 bya = first prokaryotes
2.7 bya= oxygen accumulates
2.1 bya = eukaryotes
1.5 bya= multicellular eukaryotes
1.0 bya= ancestors of land plants
540 mya= Cambrian explosion (aquatic) and appearance of animals
500 mya = first true plants and colonization of land

Question 29

what are phylogenetic trees

Answer 29

visual representations of evolutionary history among organisms - show ancestor - desendant relationships

Question 30

what is a species

Answer 30

groups of actually or potentially interbreeding members that produce viable fertile offspring

Question 31

what is the Biological Species Concept

Answer 31

species united by being reproductively compatible

gene flow: holds populations together genetically

Question 32

what are the three largest classifications of life

Answer 32

Archaea, Bacteria, and eukarya

Question 33

what are the four main groups of euaryotes

Answer 33

fungi, protists, animals, plants

Question 34

briefly characterize: plants

Answer 34

multicellular autotrophs
internal digestion
cell walls- cellulose
food source for humans

Question 35

briefly characterize: animals

Answer 35

heterotrophs
internal digestion
no cell walls
multicellular

Question 36

briefly characterize: protists

Answer 36

autotrophs and heterotrophs
external and internal digestion
cell walls and no cell walls
mainly unicellular some multicellular

Question 37

briefly characterize: fungi

Answer 37

mainly multicellular
heterotrophs
cell walls- chitin
external digestion

Question 38

why is their so much biodiversity

Answer 38

environments are constantly changing
random mechanisms of evolution
natural selection and adaptation