4.2- Sexual Reproduction In Plants Flashcards by Harriet Edwards

What is dehiscence ?

Splitting open of anther to release pollen

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What does diploid mean ?

Full chromosome number of 48

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What is the exine ?

Outer layer of pollen grain that provides a tough cell wall to resist desiccation

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What is haploid ?

Half the chromosome number

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What is the intine ?

Inner layer of pollen grain made of cellulose

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What is a pollen grain ?

Structure that contains male gamete of flowering plant, actual gametes are in the nuclei

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What is a pollen sac ?

Structure where pollen grains develop, anther has 4 pollen sacs

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What is the tapetum ?

Layer of cells around pollen sac that provides nutrients and regulatory molecules to developing pollen grains

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What is the embryo sac ?

Region of the ovule that contains the female gamete

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What are integuments ?

Outer layer of the ovule that forms the seed coat after fertilisation

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What is the micropyle ?

Small opening into the ovule through which the pollen tube enters the ovule

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What is the ovule ?

Within the ovary that consists of integuments, nucellus, embryo sac and female gamete.
Develops into the seed after fertilisation

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What is the nucellus ?

Layer of cells surrounding the embryo sac that provides nutrients

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What is the funicle ?

Stalk that attaches an ovule or seed to ovary wall

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What is the cotyledon ?

Seed leaves

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What does dormancy mean ?

Period when active growth is suspended. Germination occurs when specific conditions are met.

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What is an embryo ?

Collection of cels arising from mitosis of zygote that develops into a plant

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What is the plumule ?

Developing shoot

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What is the radicle ?

Developing root

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What is a seed ?

Structure developed from a fertilised ovule containing an embryo and food store within the seed coat/ testa

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Is an angiosperm diploid or haploid ?

Diploid

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What are the male spores of an angiosperm ?

Pollen grains produced in the anther

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What are the female spores of an angiosperm ?

Embryo sac produced in the ovule

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What is an haemaphrodite ?

1 flower contains male and female reproductive organs

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What are the 2 methods of pollination ?

Wind or insect

What is the function of a sepal ?

Protect and enclose developing bud

What is the function of petals ?

Attract insects for pollination

What is the function of the filament ?

Supports the anther, transports water, mineral ions and sucrose for pollen formation

What is the function of the anther ?

Pollen grains develop and transfer to insects here

What is the function of the stigma ?

Receive pollen during pollination

What is the style ?

Where male gametes pass down during fertilisation via the pollen tube to reach ovules

What is the function of the ovary ?

Contain ovules that can develop into a fruit

What are the adaptations of a wind pollinated flower ?

Anthers hang outside so pollen is caught by wind Lots of smooth pollen increases chance of pollination Produce small pollen grains to be carried by wind Lots Stamen provide large surface area

What provides nutrients and regulatory molecules in male gamete development ?

Tapetum

What are the names of the 2 nuclei produced in male gamete development ?

Regenerative and tube nucleus

In male gamete development how many cells does each mother cell form when they undergo meiosis ?

4 haploid cells- Tetrad

In male gamete development what does the regenerative nucleus produce via mitosis ?

2 male nuclei

What happens in male gamete development when pollen matures ?

Anther outer layers dry out causing tension in lateral grooves

How many ovules does 1 ovary contain the female gamete ?

1 or more

What undergoes mitosis in female gamete development and what is produced ?

Megastore mother cell producing 4 haploid cells, 3 of these disintegrate

How many rounds of mitosis does the 1 haploid cell undergo in female gamete development ?

3, producing 8 haploid nuclei

What does the fusing of 2 haploid nuclei create in female gamete development ?

Haploid polar nucleus

What does female gamete development produce ?

2 synergids 1 oosphere/ female gamete 3 antipodals 1 polar nucleus

What is pollination ?

Transfer of pollen grains from the anther to the mature stigma of a plant of the same species resulting in fertilisation

What is self pollination ?

Pollen from anther of a flower transfers to mature stigma of the same flower/ plant

What is cross pollination ?

Pollen is transferred from anthers of 1 flower to mature stigma on another plant of the same species

What are the genetic implications of self pollination ?

Inbreeding Depend on independent assortment, crossing over and mutations for genetic variation Greater chance of harmful allele fertilisation Preservation of successful genomes

What are the genetic implications of cross pollination ?

Outbreeding Increased genetic variation Reduced chance of producing harmful alleles Species can adapt top their environments increasing survival rate

How is cross pollination ensured ?

Dichogamy Anther below the stigma so pollen doesn’t fall on it Genetic incompatibility Separate male and female plants/ flowers

What is dichogamy ?

Structures developing at different rates

What is protandry ?

Stamen ripens before the stigma

What is double fertilisation ?

Process of a male and female gamete fusing to produce a zygote in seed plants

What do the 2 fusions in double fertilisation form ?

Zygote and endosperm

What does the pollen grain in double fertilisation germinate in ?

Sucrose solution secreted by stigma

What does the pollen tube nucleus code for in double fertilisation ?

Hydrolases- Cellulases and proteases

What structure becomes the seed ?

Testa

What are the 2 types of fruits and seeds ?

Dicotyledons and monocotyledons

What happens when a monocotyledon becomes dormant ?

Reduces metabolic rate until conditions reach optimum for germination

What are the different seed dispersal methods ?

Wind Transport Rolling Bursting Water carrying

How is the testa adapted for survival ?

Chemically resistant to protect the embryo

What happens to a seeds water content when dormant ?

Reduced to survive drought

What is germination ?

The biochemical and physiological processes through which a seed becomes a photosynthesising plant

What conditions are required for germination ?

Suitable temperature Water Oxygen

Why is water required for germination ?

To mobilise enzymes for transport in the xylem and phloem Makes cells turgid

How do seeds uptake water ?

Via the micropyle

What breaks down starch in germination ?

Amylase hydrolyses starch into maltose

What breaks down proteins in germination ?

Protease hydrolyses proteins to amino acids

What is the name of the plant growth regulator in seeds ?

Gibberelic acid

What affects does gibberelic acid have in the aleurone layer ?

Switches on genes which results in transcription and translation producing protease and amylase enzymes