BY5.3 - Plant Reproduction Flashcards
Name and give the functions of the male reproductive organs of an angiosperm
Collective name: Stamen
1) Filament - supports the anther - contains PHLOEM TISSUE - supplies anther with sucrose and other organic molecules for POLLEN GRAIN FORMATION
2) Anther - Produces pollen grains - contain male gametes
Name and give the functions of the female reproductive organs of an angiosperm:
Collective: Carpel
1) Ovary - contains OVULES - contain female gametes
2) Style - stalk structure
3) Stigma - surface receives pollen
What is a receptacle?
Apex of the flower stalk
What are sepals?
leaf - like structures which protect the flower in bud
What is a corolla?
landing platform for insects
How do petals attract insects?
- Brightly coloured
- Scented
- Have nectar
What is pollination?
The transfer of pollen grains from the anther to the stigma of a plant of the same species
What is Self-Pollination?
The transfer of pollen from the anthers to the stigma of the same flower/different flower of the same plant
What is Cross-Pollination?
When pollen is transferred from the anther of one flower to the stigma of a flower on a different plant of the same species
What is the difference in anthers between Insect and Wind Pollinated flowers?
Insect Pollinated : inside the Flower
Wind pollinated : Outside the flower so wind can blow pollen away
What is the difference in Stigmas between Insect and Wind Pollinated flowers?
Insect pollinated: Inside the flower
Wind pollinated: large, feathery stigmas
- large surface area to catch pollen grains
What is the difference in pollen grains between insect and wind pollinated plants?
Insect: small amount, sticky pollen
Wind: - large amount
- Small, smooth, light pollen
What is the biological term for self-fertilisation?
Inbreeding
What is the biological term for cross-fertilisation?
Outbreeding
How is genetic variation generated in the genotypes of Self-fertilised species?
1) Random assortment / crossing over in meiosis
2) mutation
What effect does Inbreeding have on the genotype of a plant species?
less genetic variation in genotype
What is an advantage of Inbreeding?
Offspring produces will have genotypes/phenotypes that are adapted to a stable environment
Why is outbreeding more important in terms of evolution?
Different genotypes are required for Natural Selection to occur
What is the name of the thick outer wall of a pollen grain?
Exine
What is the name of the thin inner wall of a pollen grain?
Intine
Describe the formation of a pollen grain:
1) Diploid cells in the pollen sac undergo meiosis to form haploid cells
2) each haploid cell develops into a pollen grain with an exine and intine
3) When the pollen is ripe, the outer layers of the anther dry out
4) the pollen sacs curl away
5) Pollen grain is exposed
What is fertilisation?
The process whereby the male gamete fuses with the female gamete to produce a zygote
Describe the process of fertilisation in plants:
1) pollen grain lands on stigma
2) Pollen grain absorbs water and germinates
- pollen tube forms
3) Pollen tube secretes pectinase enzymes, digesting style tissues
4) Pollen tube moves down style and enters ovule via the micropyle
5) tip of tube bursts
6) Male gamete nucleus enters embryo sac
7) male nucleus fuses with female nucleus
8) zygote develops
What does an Embryonic Plant consist of, and how is it formed?
1) Diploid zygote divides by mitosis - forms embryonic plant
2) Consists of:
a) plumule
b) radicle
c) endosperm
d) cotelydons (1-2)
What is the endosperm, and what is it formed from?
1) food reserve for developing embryo
2) formed from embryo sac
What is a plumule?
An embryo shoot
What is a radicle?
embryo root
What is a testa, and what is it formed from?
SEED COAT Formed from INTEGUMENTS
What happens to the Micropyle after fertilisation?
nothing - It remains but in the testa
What is the seed formed from?
fertilised ovule
What is a fruit formed from?
fertilised ovary
What are Monocotyledons?
seeds which contain one cotelydon
which forms the first leaf
Cotyledon surrounded by endosperm e.g. cereals
What are Dicotyledons?
seeds which contain two cotelydons
cotelydons contain endosperm
e.g. broad bean
What are the 3 main requirements for successful germination?
1) temperature - optimum needed for enzymes in germination
2) water - needed for mobilisation of enzymes
- cell transport
- cell vacuolation
3) oxygen - aerobic respiration -> ATP -> metabolism and growth (mitosis)
How do broad beans (dicotyledons) germinate?
1) Water absorbed - tissues swell, enzymes mobilise
2) testa ruptured
3) Radicle pushes through testa downwards
4) plumule pushes upwards - Bent over into hook
5) amylase hydrolyses starch to maltose - maltose transported to growing points for respiration
6) plumule emerges, unfurls and begins photosynthesis
7) Cotyledons food reserves are depleted
Why is the plumule bent over when it emerges from the testa?
To prevent soil abrasion
What occurs to the cotyledons in germination?
1) remain below ground
2) endosperm get depleted within cotyledons
