Plant Reproduction Flashcards
Name the male parts of a flower
The anther and filament, together called the stamen
Name the female parts of a flower
Stigma, style, ovary, ovule. Together called the carpel
What is the function of the filament in a flower?
Contains the xylem and phloem that supply the anther
What is the function of the anther?
To produce pollen
Describe/draw a cross section of an anther
The anther should contain four pollen sacs. Each pollen sac is surrounded by tapetum. This is a food store and will provide energy for future cell divisions. Around this is a fibrous layer
, then a protective epidermis
What is the term for an anther splitting to release the pollen?
Dehiscence
Give the steps of pollen formation
Diploid pollen mother cells divides by meiosis-> a tetrad of haploid microspores. Microspore nucleus divides by mitosis forming a tube nucleus and a generative nucleus. Intine and exine layers develop around the cell. This is now a pollen grain.
Name the eight nuclei in the pollen sac and give their position
Three at the top are antipodal, two in the middle are polar, two synergids and an egg cell at the bottom
Give the steps in embryo sac formation
A mother megaspore cell divides by meiosis to form 4 haploid megaspore cells. Three degenerate, one survives and goes through three rounds of mitosis
Name the walls around the ovule
Inner and outer integument
Name the stalk that connects the ovule to the ovary
The funicle
Name the hole at the bottom of the ovule that the pollen tube enters through
Micropyle
How are flowers adapted for insect pollination?
Pollen is barbed to hook onto insect fur. Nectar, a scent, and brightly coloured petals. Sticky stigma
How are flowers adapted for wind pollination?
Pollen is small, smooth and light, produced in large numbers. No scent, no nectary, small green petals. Feathery stigma and exposed anthers
What are cross and self pollination?
Cross pollination is when pollen travels from the anther of one plant and lands on the stigma of another. Self pollination the pollen lands on the stigma of the same plant
What are the advantages and disadvantages of cross pollination?
Advantage is that it increases genetic variation, which helps species adapt to changing environments. However self pollination is more suited to a stable environment.
How do plants prevent self pollination?
Having the stigma above the stamen, having them mature at different times, genetic incompatibility, or separate male/female flowers or plants
What is pollination?
When pollen lands on the stigma
What happens after pollination?
The pollen germinates to produce a pollen tube, which digests a path down the style to the ovary. The generative nucleus divides by mitosis to produce two male gametes
What is the function of the tube nucleus in pollen?
To control the growth of the pollen tube and code for production of hydrolytic enzymes
What is double fertilisation?
When the tip of the pollen tube bursts, one male nucleus fertilises the egg, forming the diploid zygote. The other fertilises the two polar nuclei, forming the triploid endosperm
What is the function of the endosperm?
It is a storage tissue that normally provides nutrients to the developing embryo
After fertilisation, what do the ovule, ovary, funicle and integuments become?
The ovule becomes the seed, ovary the fruit, funicle leaves a scar called the hilum, integuments become the testa
Which part of the embryo forms the root, and which part the shoot?
Radicle becomes the root, plumule the shoot
What are the two possible food stores of a seed?
The endosperm or the cotyledons
What are the two groups flowering plants are divided into based on their seeds?
Monocotyledons and dicotyledons
List four ways seeds can be dispersed
Wind, water, mechanical, animals
Give the three conditions seeds need for germination
Water, oxygen, suitable temperature
Why do seeds need to inbibe water to break down food reserves?
Water activates the gene coding for gibberellin. Gibberellin diffuses to the aleurone layer and causes production of amylase, which breaks down the starch in the food store to maltose
Why do seeds need to inbibe water to respire aerobically?
When water is imbibed through the micropyle the cotyledons swell and the testa split to allow entry of more oxygen for aerobic respiration
What happens to a seed planted too deep in the soil?
It will use its full food store before the leaves reach the surface to photosynthesise
