Reproduction and Growth : Plant Reproduction

Question 1

define reproduction.

Answer 1

• the ability of living organisms to produce offspring

Question 2

what environment is sexual reproduction an advantage in?

Answer 2

• a changing environment
• or where there is a threat of disease from pathogens

Question 3

what three steps need to occur in order for a new plant to be produced by sexual reproduction?

Answer 3

• pollination
• fertilisation
• germination

Question 4

what are the offspring produced in asexual plant reproduction called?

Answer 4

• clones

Question 5

what environment is asexual reproduction an advantage in?

Answer 5

• a stable environment
• because it allows parent plants with advantageous adaptations to produce offspring with the same beneficial characteristics

Question 6

describe the natural methods of asexual reproduction in plants.

Answer 6

• runners : a new plant is produced where the runner touches the ground
• tubers: swollen underground stems containing lots of stored food. one plant can produce many tubers which can each grow many shoots which form new plants
• bulbs: underground buds with thick fleshy leaves containing stored food. a main shoot will grow out of the parent bulb and another will grow out of the side ‘daughter’ bulb, forming two plants

Question 7

describe an artificial method of asexual reproduction in plants.

Answer 7

• to grow plants from cuttings
• a piece of a plant’s stem, with a few leaves attached, is cut from a healthy plant
• this is planted in damp compost, where it will grow roots and develop into a new plant

Question 8

what are flowers?

Answer 8

• the sex organs of plants

Question 9

what are the three main functions of flowers?

Answer 9

• production of gametes
• sites of pollination and fertilisation
• sites of seed and fruit formation

Question 10

what are the gametes of flowers?

Answer 10

• pollen: gamete produced in the anther, the male part (stamen) of the flower
• ova: gamete produced in the ovules found in the ovary within the female part (carpel) of the flower

Question 11

what is cross-pollination?

Answer 11

• the transfer of pollen from the anther of one flower to the stigma of another flower on another plant

Question 12

what is self-pollination?

Answer 12

• when the pollen doesn’t reach a different plant
• less commonly seen

Question 13

label the structure of a flower.

Answer 13

one note page

Question 14

what are the two types of adaptions of flowers?

Answer 14

• wind-pollinated
• insect-pollinated

Question 15

how is the stamen different in insect pollinated vs wind pollinated flowers?

Answer 15

• IP - enclosed within the flower
• WP- exposed outside of petals

Question 16

how is the stigma different in insect pollinated vs wind pollinated flowers?

Answer 16

• IP - enclosed within flower and sticky
• WP- exposed outside of petals, often ‘feathery’

Question 17

how are the petals different in insect pollinated vs wind pollinated flowers?

Answer 17

• IP - large and brightly coloured
• WP- small, usually green

Question 18

how are the nectaries different in insect pollinated vs wind pollinated flowers?

Answer 18

• IP - present- produce sugary fluid to attract insects
• WP - absent

Question 19

what are the two types of gametes in sexual reproduction?

Answer 19

• mobile male gamete (sperm and pollen)
• stationary female gamete (ovum)

Question 20

what must the gametes do?

Answer 20

• fuse (fertilisation)
• forms a single cell called a zygote
• zygote will divide many times by mitosis to form all the cells of the new organism

Question 21

describe the processes of pollination and fertilisation?

Answer 21

1. In plants pollen grains are deposited onto the stigma.
2. The pollen grain normally grows a pollen tube which grows down through the
   style.
3. Enzymes are secreted at the tip of the tube which digest the tissues of the style.
4. When the tube reaches an ovule the male gamete travels through the tube
   entering the ovule through a small hole called the micropyle.
5. It then fuses with the female gamete (ovum) in the process of fertilisation.
6. The fertilised ovum divides by mitosis to form the embryo
7. The ovule develops into the seed.
8. The ovary develops into the fruit

Question 22

label the pollination and fertilisation diagram.

Answer 22

one note page

Question 23

describe fruit formation.

Answer 23

The fertilised ovule becomes a seed and the ovary becomes a fruit, whose job it is to disperse the seeds. Specifically the following happens:
1. The zygote develops into an embryonic plant with a small root (radicle) and shoot (plumule)
2. The other contents of the ovule develop into COTYLEDONS which will be a food store for the young plant when it germinates.
3. The ovule wall becomes the seed coat, or TESTA (the hard coating of the seed)
4. The ovary wall becomes the fruit coat

Question 24

what do germinating seeds require?

Answer 24

• a great deal of energy quickly
• they therefore use their food stores using enzymes which break down carbohydrate stores
• and used as fuel in respiration to release energy
• this occurs until the leaves are in a position to photosynthesis

Question 25

what do plants need in order to germinate?

Answer 25

• oxygen - to aerobically respire
• warmth - optimum temperature for enzymes
• water - to activate the enzymes

Question 26

describe an experiment to investigate the conditions needed for germination.

Answer 26

Cress seeds are added to cotton wool in test tubes.
 Tube A is put in a fridge (no warmth) and the rest are kept on a windowsill.
 In tube C, the cotton wool is moistened with boiled water and an oxygen absorber such as sodium
pyrogallol is added (no oxygen).
 Tube E is wrapped in foil (no light).
 The cotton wool in tube B is kept dry (no water).
 Tube D has all the conditions present.
Check for germination after 2-3 days - you could combine class results and calculate % germination
or mean length of seed for each condition.