Sexual reproduction

Question 1

reproduction success meaning

Answer 1

determined by its ability to produce fertile offspring that survive to reproductive maturity: measured by the individual

Question 2

biological fitness meaning

Answer 2

how likely alleles will be present in future generations: measured by the allele

Question 3

two types of reproduction

Answer 3

asexual and sexual

Question 4

process of sexual reproduction

Answer 4

two haploid gametes fuse in a process called fertilisation to create a zygote; offspring has mixed genetics- one set of paternal chromosomes and one set of maternal chromosomes

Question 5

advantages of sexual reproduction

Answer 5

• introduces genetic variation
• offspring may gain a selective advantage

Question 6

disadvantages of sexual reproduction

Answer 6

• requires a greater expenditure of time + energy
• requires more investment by an individual than asexual reproduction

Question 7

unisexual meaning

Answer 7

animals which are separate male and female individuals

Question 8

hermaphrodite meaning

Answer 8

animals in which individual has both male and female reproductive organs

Question 9

hermaphrodite better for

Answer 9

low population densities or non-motile

Question 10

hermaphrodite disadvantage

Answer 10

less genetic variation + larger energy expenditure to grow + maintain two sets of reproductive organs

Question 11

fertilisation

Answer 11

in which gametes meet, and do not get dehydrated in the process

Question 12

external fertilisation

Answer 12

occurs outside the body, more suited to aquatic/moist environments

Question 13

internal fertilisation

Answer 13

occurs within the body, suited to terrestrial organisms

Question 14

summary on external fertilisation

Answer 14

• external = less time + energy for parents, but more gametes to ensure young survive
• usually results in less parental care for young
• release of gametes and distribution via biotic/abiotic factors results in less competition for food + living space
• can be synchronised over species using environmental cues or pheromones

Question 15

amphibians’ reproduction

Answer 15

life cycle involves both land and water
- most amphibians: gametes released in fresh water; lack of parental care, tadpoles = easy prey
- some frogs: eggs fertilised externally but swallowed by female; extreme parental care increases survival chances

Question 16

summary of internal fertilisation

Answer 16

• internal: protects gametes from dehydration + immediate predation
• requires fewer gametes for sufficient no. of offspring
• usually means less offspring + more parental care to ensure survival of offspring

Question 17

oviparous

Answer 17

development in which internally fertilised egg develops shell and laid in external environment

Question 18

eviviparous

Answer 18

development in which fertilised egg becomes embryo, nurtured in female’s body, nutrients through placenta, born alive

Question 19

ovo-viviparous

Answer 19

development in which eggs with yolk for nourishment retained inside mother’s body + hatched, newly hatched young are born alive

Question 20

reptiles

Answer 20

most have eggs that are fertilised internally, then deposited outside mother’s body
- eggs can be hard-shelled or soft and leathery

Question 21

birds

Answer 21

internal fertilisation preceded by courtship
- once egg fertilised, laid with calcium carbonate shell that hardens with contact with air, incubated by parents to maintain warmth
- hard egg = protection, parental care

Question 22

mammals

Answer 22

all undergo internal fertilisation

Question 23

monotremes

Answer 23

oviparous; after internal fertilisation, eggs develop outside mother’s body
- e.g. platypus + echidna

Question 24

marsupials

Answer 24

offspring develop internally for short time after fertilisation before continue development in pouch
- can have three offspring in different stages of development at once: one out of pouch, one in pouch, one fertilised ovum in uterus

Question 25

embryonic diapause

Answer 25

development of youngest triggered when second-youngest detaches from pouch, delay in embryo development

Question 26

eutherians

Answer 26

placental mammals, offspring develops inside mother’s body with placenta
- placenta gives nutrients, diffuses waste
- few young but massive investment

Question 27

angiosperms vs gymnosperms

Answer 27

angiosperms: flowering plants
gymnosperms: conifers

Question 28

flower

Answer 28

reproductive organ in plants, contains male or female parts or both

Question 29

female angiosperm reproductive parts

Answer 29

carpel
- Stigma: sticky surface, where pollen goes
- Style: joins stigma to ovary
- Ovary: where ovules are formed, develops into the fruit

Question 30

male angiosperm reproductive parts

Answer 30

stamen
- Anther: where pollen is formed
- Filament: stalk that carries anther; length determines pollination method(longer for wind, shorter for insects)

Question 31

cross-pollination

Answer 31

relying on outside agents to transfer pollen from anthers to stigmas

Question 32

pollination by abiotic factors

Answer 32

inefficient + effective; requires large amounts of energy to make a lot of pollen
- used by conifers
- e.g. white cypress pine

Question 33

pollination by biotic factors

Answer 33

reduces wastage of pollen, right flower pollinated
- efficient to have mutualist relationship with animal
- reward for pollination = fruit or nectar
- insects/animals attracted to color + nectar
- used by angiosperms
- e.g. bottlebrushes

Question 34

seed dispersal

Answer 34

occurs after pollination + fertilisation
- seeds: fertilised ovules from inside ovary

Question 35

advantages of wide distance dispersal of seeds

Answer 35

prevents overcrowding + competition for resources, increases chance of continuity of species in other locations

Question 36

germination

Answer 36

development of plant from a seed or spore after period of dormancy
- plant embryo: dehydrated + dormant, survives adverse conditions until it lands in sufficient environment for growth
- develops radicle(young root) for water + nutrients and plumule(young stem) to grow leaves for photosynthesis