Organisms and evolution - 2

Question 1

what is sexual reproduction?

Answer 1

the production of new living organisms by combining genetic information from two individuals of different sexes

Question 2

what are the benefits of sexual reproduction?

Answer 2

• maintains greater genetic variation
• allows species to adapt and survive in a changing environment
• enables long term evolutionary change

Question 3

what is fertilisation?

Answer 3

random process resulting in new combinations of alleles

Question 4

what is variation?

Answer 4

differences that exist between individuals in a population determined by the alleles that are inherited

Question 5

what are some of the costs of sexual reproduction?

Answer 5

• male half of population can’t produce offspring
• slow reproduction rate
• metabolic expenditure high
• interrupts successful genome

Question 6

what is asexual reproduction?

Answer 6

offspring arise from a single organism

Question 7

when is asexual reproduction successful?

Answer 7

succesful in very narrow, stable niches

Question 8

what is asexual reproduction called in plants?

Answer 8

vegative cloning

Question 9

what is asexual reproduction called in animals?

Answer 9

parthenogenesis

Question 10

what does asexual reproduction allow plants to do?

Answer 10

allows plants to successfully recolonise disturbed habitats

Question 11

what can increase genetic variation in prokaryotes?

Answer 11

horizontal gene transfer

Question 12

what is parthenogenesis?

Answer 12

when offspring develops from an unfertilised egg

Question 13

where is parthenogenesis most common?

Answer 13

in cooler climates with low parasite diversity

Question 14

what is meiosis?

Answer 14

the process of nuclear division that results in the production of haploid gametes

Question 15

what cells are the only diploid cells capable of carrying out meiosis?

Answer 15

gamete mother cells

Question 16

where are gamete mother cells located?

Answer 16

located in sex organs

Question 17

what happens before meiosis begins?

Answer 17

each chromosome separates forming two identical chromatids held together by a centromere

Question 18

what are homologous chromosomes?

Answer 18

pairs of chromosomes

Question 19

what do homologous chromosomes have in common?

Answer 19

• same size/length
• same location of centromere
• same location of genes

Question 20

what can be done to increase variation during meiosis ?

Answer 20

• independent assortment

- crossing over

Question 21

what does independent assortment produce?

Answer 21

produce gametes with varying combinations of maternal and paternal chromosomes

Question 22

how can the number of different combinations from independent assortment be calculated?

Answer 22

2^n (n=haploid number)

Question 23

what is independent assortment?

Answer 23

the random order in which chromosomes line up

Question 24

what is the cross over point called?

Answer 24

chiasma

Question 25

what happens during crossing over?

Answer 25

the inner chromatids break at chiasma and swap a section of their genetic material

Question 26

what does crossing over result in?

Answer 26

results the recombination of alleles

Question 27

what are linked genes?

Answer 27

genes on the same chromosome

Question 28

what does a greater distance between linked genes show?

Answer 28

greater frequency of recombination

Question 29

what chromosomes determine if an organism is male or female?

Answer 29

sex chromsomes

Question 30

what determines the development of male traits?

Answer 30

sex-determing region Y (SRY) gene on Y chromosome

Question 31

what is the SRY gene?

Answer 31

provides instructions for making transcription factor

Question 32

what is the transcription factor for male traits known as?

Answer 32

testis-determing factor (TDF)

Question 33

what does the SRY gene activate?

Answer 33

activates male genes in genome

Question 34

what is a transcription factor?

Answer 34

protein that binds to specific regions of DNA

Question 35

what does transcription factors help to control?

Answer 35

helps control the activity if particular genes

Question 36

what are the sex chromosomes for a female?

Answer 36

XX

Question 37

what are the sex chromosomes for a male?

Answer 37

XY

Question 38

what are the sex chromosomes for a female bird?

Answer 38

ZW

Question 39

what are the sex chromosomes for a male bird?

Answer 39

ZZ

Question 40

what is the default pathway for humans?

Answer 40

females

Question 41

which chromosome is smaller, X or Y?

Answer 41

Y chromosome

Question 42

what causes sex-linked patterns of inheritance?

Answer 42

X-chromosome has many genes that don't have homologous genes on the Y-chromosome

Question 43

are X-linked disorders more common in females or males?

Answer 43

males

Question 44

name some examples of x-linked disorders

Answer 44

- colour blindness | - haemophilia

Question 45

why are most genes on one X-chromosme in each cell inactivated in females?

Answer 45

so that the cells have a single working copy of the X-chromosme genes

Question 46

is X inactivation a random or non-random process?

Answer 46

random process

Question 47

what is what factors lead to sex determination?

Answer 47

genetic or environmental factors

Question 48

what are the 4 environmental factors?

Answer 48

- temperature - size - competition - parasitic infection

Question 49

in what species are temperature dependant sex determination (TSD) most common in?

Answer 49

reptiles, some birds and fish

Question 50

what enzyme is influenced by temperature and therefore determines sex in TSD?

Answer 50

aromatase

Question 51

what is a hermaphrodite?

Answer 51

an animal that has both male and female sex organs or other sexual characteristics