R2101 - Structure & function of flowers fruits & seeds

Question 1

3.1 State the function of flowers.

Answer 1

• purely reproduction
• aid pollination
• give rise to seeds and fruits

Question 2

3.1 State the meaning of monoecious with two examples.

Answer 2

Monoecious plants have separate male and female parts on the same plant.

• Cucumis spp. (Cucumbers)
• Alnus spp. (Alders)

Question 3

3.1 State the meaning of dioecious with two examples.

Answer 3

Dioecious plants have male and female flowers on separate plants – so the individual plants are effectively either male or female.

• Ilex spp. (hollies)
• Salix spp. (willows)

Question 4

3.1 State the meaning of the term pollination.

Answer 4

The transfer of pollen from the stamen (male) to the stigma (female) of a flower - enabling the ovules to be fertilised.

Question 5

3.1 Describe the characteristics of wind pollinated plants - include flower structure and pollen

Answer 5

• Flowers - small, inconspicuous, green petals, reduced in size or absent
• Flower structure - often dangles loosely, stamens hang out of the flower.
• No scent or nectar
• Pollen - large quantities made, light and smooth and easily carried by wind
• Anthers - larger, loosely attached to long filaments, to release pollen more easily
• Stigmas - feathery, hang outside flower to catch passing pollen grains
• Grasses are wind-pollinated, as are many trees
• Catkins produced by trees produce are an example of wind pollination

Question 6

3.1 Give two examples of wind pollinated plants.

Answer 6

• Grasses are wind-pollinated e.g. zea mays (corn)
• Catkins produced by trees produce are an example of wind pollination e.g. Corylus avellana (hazel with catkins)

Question 7

3.1 Describe the characteristics of bee pollinated plants (8) - include flower structure and pollen.

Answer 7

• Shallow flowers with short floral tubes to match the length of the bee’s tongue
• Bright white, yellow or blue flowers
• Nectar guides sometime only visible to bees
• Sugar-rich nectar
• Sticky scented pollen
• Sweet, mild scent
• A landing stage, e.g. Antirrhinum, Digitalis
• Sometimes highly adapted to particular bee species

Question 8

3.1 Give two examples of bee pollinated plants.

Answer 8

Limnanthes douglasii (poached egg plant)

Borago officinalis (borage)

Question 9

3.2 State the meaning of the term fertilisation.

Answer 9

The fusion of a male gamete from pollen with a female gamete in the ovule to produce the embryo.

Question 10

3.2 State the meaning of the term fruit.

Answer 10

A fruit is formed from the ovary after fertilisation.

Question 11

3.2 State the term of the meaning seed.

Answer 11

A seed is formed from the ovule after fertilisation.

Question 12

3.2 State the function of fruits.

Answer 12

• distribution and protection of the seed
• may impose dormancy until conditions are favourable

Question 13

3.2 State the function of seeds.

Answer 13

• distribution and protection of the embryo
• may impose dormancy until conditions are favourable for germination
• gives rise to new plants

Question 14

3.2 Describe the means by which seeds are dispersed - wind with named examples.

Answer 14

wings - wing-like structures that spin in the wind as it falls from the plant e.g. Fraxinus excelsior (Ash)

parachutes - feathery parachutes attached that carry seeds long distances e.g. Taraxacum officinale (Dandelion)

censer - shaken from small pores in the fruit as the plant sways like a church censer e.g. Papaver rhoeas (poppy)

Question 15

3.2 Describe the means by which seeds are dispersed - water with named examples.

Answer 15

• fruits of plants growing in or near water are adapted to float for dispersal
• Cocus nucifera (coconut)
• Nymphaea alba (White waterlily)

Question 16

3.2 Describe the means by which seeds are dispersed - explosive with named examples.

Answer 16

• seed is distributed explosively by the fruit forming a spring mechanism as it dries
• Lathyrus odoratus (sweet pea)
• Lupinus perennis (Lupin)

Question 17

3.2 Describe the means by which seeds are dispersed - animals with named examples.

Answer 17

attachment - seed have tiny hooks to attach to fur or feathers: Gallium aparine (Goose grass)

scatter hoarding - seed is taken and buried by squirrels: Quercus robur (Common oak)

frugivory - fruit is eaten and the seeds then excreted far from the parent plant: Rubus fruticosus (blackberry)

Question 18

3.2 Describe the internal and external structure of the seed and state the function of the various parts: (10)

Answer 18

• Embryo = radicle, plumule, cotyledon, hypocotyl, epicotyl
• Testa = the seed coat
• Cotyledon = the seed leaves and food store (remember, monocots only have one of these, whilst dicots have two)
• Endosperm (in monocots) provides food for the embryo
• Plumule = forms the first shoot
• Radicle = forms the first root
• Epicotyl = elongates to grow the shoot and attaches the plumule to the cotyledon
• Hypocotyl = elongates to grow the root and attaches the radicle to the cotyledon
• Hilum = the scar showing where the seed was attached to the ovary
• Micropyle = a small gap where the pollen entered the ovule and often the place where water enters the seed to begin germination

Question 19

3.2 Describe ONE example of epigeal germination.

Answer 19

Epigeal germination is where the cotyledons emerge above ground. E.g Phaseolus vulgaris (french bean)

Question 20

3.2 Describe ONE example of hypogeal germination.

Answer 20

Hypogeal germination is where the cotyledons remain below ground. E.g. Vicia faba (broad bean)