Topic 7 Plant Reproduction Flashcards
What are the differences between asexual and sexual reproduction?
Sexual:
- two parents
- offspring genetically different to parents
Asexual:
- one parent
- offspring identical to parents = clones
What are the advantages of sexual reproduction?
- genetic variation in population
- species can adapt to new environments
- less likely to be affected by a disease as a whole
What are the advantages of asexual reproduction?
- population can increase rapidly
- can exploit a suitable habitat quickly
What are the disadvantages of sexual reproduction?
- takes time + energy to find a mate
- not possible for isolated individuals
What are the disadvantages of asexual reproduction?
- no variation in population
- species only suited to one habitat
- disease may affect all individuals in population
What are three examples of plants that reproduce asexually?
- tubers (potatoes)
- runners (strawberry plants)
- bulbs (onions)
What is the male part of the flower?
Stamen
What is the female part of the flower?
Carpel
Where is the male gamete found and made?
- pollen grain
- made in anther
Where is the female gamete found and where is it made?
- ovule
- ovary
What is fertilisation?
Fusion of male + female gamete to produce a zygote (fertilised female gamete)
- zygote undergoes cell division (by mitosis) + develops into an embryo (found in seed)
What is the function of petals?
Bright colours to attract insects
What is the function of the anther?
Produce male gametes (in pollen grains)
What is the function of the stigma?
Top of female part of flower which collects pollen grains
What is the function of the ovary?
Bottom of female part of the flower
Produces female gametes (ovules)
What is the function of the nectary?
Produces sugary nectar to attract insects
What is the function of the sepals?
Protect unopened flower bud
What is the function of the stamen?
Male parts of flower consisting of anther held up on the filament
Artificial asexual in plants .. how does this occur?
- humans cutting + planting branch elsewhere
What is pollination?
Transfer of pollen from anther to stigma
What plants do insect pollination?
Sunflowers
Dandelions
Tulips
What plants do wind pollination?
Hazel tree catkins
Rye grass
Sweet chestnut
What are petals like in an insect / wind pollinated plant?
- Large + colourful (attract insects)
2. Small + not colourful (doesn’t need to attract insects)
What is nectary / scent like in insect/wind pollinated flowers?
- Has one to attract insects
2. Doesn’t have one, doesnt need to attract insects
What is the stigma (type and position) like in insect/ wind pollinated plants?
- Sticky -> pollen attaches from insects
2. Feathery -> latch pollen in the wind
What is the stamen (position) like in insect/wind pollinated plants?
- Enclosed within flower -> insect must make contact
2. Exposed -> wind can easily blow pollen away
What are pollen grains like in insect/wind pollinated plants?
- Barbed -> stick to insect bodies
2. Small + smooth + large quantities -> transported by wind
What is self pollination and what is cross pollination?
- Pollen falls from anther to stigma of same flower
2. Pollen travels to different flower of same species (more variation)
What are the methods plants use to encourage cross pollination?
- Stigma above stamen
2. Stigma + stamen mature at different times
What happens once the pollen grain has arrived on a stigma?
- Grows pollen tube -> stimulated by chemicals secreted by stigma (sugars)
- Different flowers -> secrete diff chemicals -> only grows tube on own species
Describe the route of the pollen tube and fertilisation
- Pollen tube grains down style
- Enzymes are secreted by the tip, which digests tissues of style
- Inside tube, male gamete travels to ovule
- When tube reaches ovule, male gamete enters thru micropyle (small hole)
- Pollen tube dissolves + pollen grain nucleus fuses w nucleus of female gamete (fertilisation)
- Zygote forms, cell division -> embryo
After fertilisation : What does the fertilised ovule become?
Seed
After fertilisation: What does ovary wall become?
Fruit
After fertilisation: What do the other flower parts do?
Fall off
What is a dormant seed?
No metabolic reactions occurring
What do the contents of the ovule become?
Food store
What does the ovule wall become?
Seed coat (testa)
What is the importance of the seed food store?
- energy
- provides protein for growth
- doesn’t need to photosynthesise
- underground, so needs food store
What is the importance of the testa?
- protects embryo eg when eaten by animal
Testa is waterproof
What is plumule?
Embryo shoot (inside seed)
What is radicle?
Embryo root (inside seed)
What is the importance of seed dispersal?
- reduce competition between plants for space, light, water, nutrients eg nitrates
What is germination?
- process controlled by enzymes, in which a seed develops into a young plant
When does germination end?
- when shoot appears out of soil (as it can now photosynthesise)
What allows germination to begin?
- Water
- softens testa + allows it to split so shoot can exit seed
- activates enzymes to start chemical reactions for growth
- Oxygen
- needed as reactant in aerobic respiration to release energy so that seed can grow - Suitable temperature
- enzymes break down starch into glucose which is used during aerobic respiration to release energy for growth
What do enzymes in the seed do?
- Amylase breaks down starch into maltose, and maltase breaks that down into glucose
- which is used in aerobic respiration for growth
Explain how you would do the practical investigating conditions for seed germination
5 boiling tubes
- Dry cotton wool, room temp, light + oxygen
- Moist cotton wool, room temp, in light + oxygen
- Moist cotton wool, room temp, in dark + oxygen
- Moist cotton wool, cold temp in fridge, in dark + oxygen
- Moist cotton wool, room temp, in light without oxygen
What are results?
Those lacking water, suitable temp + oxygen wont grow
Ones in dark are yellow
