Reproduction in Flowering Plants

Question 1

what is sexual reproduction?

Answer 1

the process involving the fusion of nuclei of a male and female gamete to form a zygote

Question 2

what is asexual reproduction?

Answer 2

the process resulting in the production of genetically identical offspring from one parent without the fusion of gametes

Question 3

what are the parts of a flower?

Answer 3

• sepal
• petal
• carpel
• stamen
• flower stalk
• receptacle

Question 4

what is the structure of the sepal and its function?

Answer 4

modified leaves that form the outermost layer of the floral leaves, enclosing and protecting the developing bud

Question 5

what is the structure of the petal and its function?

Answer 5

modified leaves that form the most obvious part of the flower that attracts insects that help pollinate the flower

Question 6

what does the carpel comprise of and their functions?

Answer 6

1. stigma - swollen structure where pollen lands, when mature, it secretes a sugary fluid that stimulates the pollen grains to germinate
2. style - elevates the stigma to receive pollen
3. ovary - contains one or more ovules and becomes the fruit upon successful fertilisation
4. ovule - contains the female gamete and becomes the seed upon successful fertilisation

Question 7

what does the stamen comprise and their functions?

Answer 7

1. anther - where pollen grains are produced and when matured, it splits open to release pollen grains
2. filament - holds the anther in a suitable position to disperse pollen
3. pollen grain - contains the male gamete

Question 8

what is the structure of the flower stalk and its function?

Answer 8

the stalk of the flower which attaches the flower to the stem

Question 9

what is the structure of the receptacle and its function?

Answer 9

the swollen part of the flower that supports the weight of the flower or fruit

Question 10

what is pollination?

Answer 10

the transfer of pollen from the anther to the stigma of a flower of the same species

Question 11

what is the difference between self-pollination and cross-pollination?

Answer 11

self-pollination occurs on the same flower or between flowers on the same plant whereas cross-pollination occurs between flowers of different plants but of the same species

Question 12

what features favour self-pollination?

Answer 12

• bisexual flowers with anthers and stigma that mature at the same time
• stigma is located below or close to the anthers
• flowers that never open

Question 13

what features favour cross-pollination?

Answer 13

• bisexual flowers where anthers and stigma mature at different times
• stigma is above and further away from the anthers
• dioecious plants that bear either male or female flowers

Question 14

what are the advantages of self-pollination?

Answer 14

• only one parent required
• beneficial qualities are more likely to be passed down to offspring
• does not depend on external factors for pollination
• higher success rate due to closeness of anthers and stigma
• less pollen and energy wasted

Question 15

what are the disadvantages of self-pollination?

Answer 15

• less genetic variation in offspring, hence less well-adapted to environmental changes
• offspring becomes weaker and smaller

Question 16

what are the advantages of cross-pollination?

Answer 16

• offspring can inherit beneficial qualities from both parents
• greater genetic variation, hence a higher chance of surviving environmental changes
• seeds are more viable and can survive longer before germination

Question 17

what are the disadvantages of cross-pollination?

Answer 17

• two parents are needed
• depends on external factors for pollination
• lower rate of success
• more energy and pollen wasted

Question 18

what are the structures of an insect-pollinated flower?

Answer 18

• brightly coloured petals with nectar guides to guide insects
• nectar present to lure pollinators
• fragrant or other smells to attract pollinators
• fairly abundant pollen
• sticky or spikey pollen to cling onto the insect
• small compact stigma that does not protrude out of the flower
• non-pendulous stamen that does not protrude out of the flower

Question 19

what are the structures of a wind-pollinated flower?

Answer 19

• small, dull-coloured and without petals, and no nectar guides
• no nectar
• no smell
• more abundant pollen
• tiny, smooth and light pollen
• large, feathery stigma which protrudes out of the flower to provide a large surface area to trap pollen
• long, pendulous filaments with protruding anthers so pollen grains can easily be shaken out

Question 20

what is the fertilisation process?

Answer 20

1. after pollination, the pollen grain of the same species germinates aftercoming into contact with the stigma, in response to the sugary fluid secreted by the mature stigma
2. pollen tube grows out of the pollen grain and male gametes enter the tube
3. pollen tube secretes enzymes to digest the surrounding tissue of the stigma and style as it grows down into the ovary from the style
4. pollen tube enters the ovule through the micropyle
5. tip of the pollen tube absorbs cell sap and bursts, releasing the male gametes
6. nucleus of the male gamete fuses with the nucleus of the ovum to form a zygote
7. ovary develops into a fruit and the ovule becomes a seed, where the zygote is the embryo in the seed