Variation And Sexual Reproduction

Question 1

state two disadvantages of sexual reproduction

Answer 1

metabolic costs are high, successful genomes are disrupted and only 50% of population produce offspring

Question 2

give an example of conditions suitable for asexual reproduction

Answer 2

narrow and stable niche, decolonising disrupted habitats

Question 3

what is an advantage of sexual reproduction

Answer 3

removes deleterious alleles, variation

Question 4

what is the method of asexual reproduction in animals

Answer 4

parthenogenesis

Question 5

what is parthenogenesis

Answer 5

when an unfertilised egg develops into an individual

Question 6

what conditions are suited for parthenogenesis

Answer 6

areas with low parasitism and cooler climates, low selection pressure

Question 7

what method of asexual reproduction involves the offspring growing out of the parents body

Answer 7

budding

Question 8

what method of vegetative cloning do daffodils use

Answer 8

bulbs

Question 9

give an example of a species that use spores to asexual reproduce

Answer 9

fungi

Question 10

what is the method of asexual reproduction in prokaryotes

Answer 10

horizontal gene transfer

Question 11

what is the first stage of meoisis one

Answer 11

long uncoiled chromosomes replicate to form two identical chromatids

Question 12

what is the process called of crossing over genes at the chiasma

Answer 12

recombination

Question 13

are the cells at the end of meoisis 1 haploid or diploid

Answer 13

haploid

Question 14

what are linked genes

Answer 14

two genes located on the same chromosome

Question 15

how many cells will be produced by one parent cell at the end of a)meoisis 1 b)meoisis 2

Answer 15

a) 2 b) 4

Question 16

what makes chromosomes homologous

Answer 16

same size, centromere position and same order of genes(or genes at the same loci)

Question 17

what is meoisis

Answer 17

process of cell division that produces gametes

Question 18

what are the two things that can control sex determination

Answer 18

genetic and environmental

Question 19

what are hermaphrodites

Answer 19

organisms with male and female reproductive systems

Question 20

what is the homologous pair of the X chromosome

Answer 20

the y chromosome

Question 21

why are the X chromosome and y chromosome considered homologous

Answer 21

small area of homologous genes near the centromere

Question 22

what are the four environmental factors that can influence sex determination

Answer 22

size, temperature of egg incubation, competition, parasite infection

Question 23

give an example of how temperature of egg incubation influences sex determination

Answer 23

Hermann’s tortoises, less that 31 degrees = males, greater that 32 degrees = female

Question 24

in what species does genetic factors influence sex determination

Answer 24

placental mammals

Question 25

what does it mean if an individual is homogametic

Answer 25

they have two identical sex chromosomes. eg human females (xx)

Question 26

what would you call an organism such as an xy male mammal

Answer 26

heterogametic

Question 27

describe the role of the sry gene in sex development

Answer 27

the sry gene is like a master switch, it controls development of organisms into males and if it is expressed it transcribes specific genes causing characteristics of males to be expressed, if not development continues as a female

Question 28

why is x inactivation necessary

Answer 28

prevent a double dosage of gene products in females (dosage compensation)

Question 29

describe x inactivation

Answer 29

random process, occurs during development , when most genes on X chromosome are inactivated

Question 30

give an example of X inactivation having an effect on the phenotype

Answer 30

tortoiseshell cats

Question 31

what is a disadvantage of having males for sexual reproduction

Answer 31

disrupt successful parent genomes, can't produce offspring