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Biology > Plant reproduction > Flashcards

Plant reproduction Flashcards

1
Q

Whats an angiosperm?

A

A plant that uses flowers for reproduction

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2
Q

What is the male spore?

A

Pollen grain

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3
Q

What is the female spore?

A

Embryo sac

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4
Q

What are the 4 layers of the recepticle?

A

Outmost is calyx, then the lining of petals called corolla.
Then male parts, followed by female.

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5
Q

What does the stamen consist of?

A

Filament and anther

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6
Q

What does the carpel consist of?

A

Ovary, style and stigma

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7
Q

What are some features of insect pollinated plants?

A

Produce nectar/scent
Colourful
Produce sticky large pollen grains
Produce small amounts of pollen
Stigma and anther within flower

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8
Q

What are some features of wind pollinated plants?

A

No nectar/scent
not colourful
Produce smooth small pollen grains
Produce large amounts of pollen
Stigma is feathery and outside
Anther outside too

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9
Q

How do insects pollinate flowers?

A

Attracted by scent of nectar and rub against the anther which transfers some pollen onto insect. The insect then goes to another plant where it rubs against the stigma depositing the pollen grain.

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10
Q

Explain male gamete development in plants

A

Pollen sacs within anther undergo meiosis, forms a tetrad/4 pollen grains. Within the pollen grains the haploid nucleus does mitosis producing 2 nuclei. A tube nucleus and a generative nucleus. The generative nucleus does mitosis to make 2 male gametes

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11
Q

What is the tapetum and where is it?

A

Tapetum surrounds pollen sac and provides nutrients for pollen grains.

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12
Q

Why do pollen grains not dry out?

A

Because they are tough and have a high sucrose content water is always provided by osmosis.

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13
Q

What is dehiscence?

A

The splitting of the anther

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14
Q

How does dehiscence occur?

A

When pollen grains are mature the anther dries out causing tension in lateral groove. This tension pulls anther wall apart forming a stomium exposing pollen grains which are carried away by the wind.

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15
Q

Explain female gamete formation in plants

A

The ovary contains more than one ovule, each ovule has a megaspore surrounded by nucellus cells. Megaspore does meiosis producing x4 haploid cells, x3 disintegrate leaving 1.
The remaining cell does mitosis x3 , producing x8 diploid nuclei.
One of these is an oosphere, 2 are synergids, 3 are antipodals. 2 fuse to make a polar nucleus.

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16
Q

What is pollination?

A

The transfer of pollen grains from the anther to mature stigma

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17
Q

What is self pollination?

A

Pollination of same flower of another flower of the same plant

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18
Q

What is cross pollination?

A

Pollination of a flower of a different plant of the same species

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19
Q

Name some self pollination implications

A

Dependent on meiosis for genetic variation
genomes are preserved
higher risk of harmful recessive alleles

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20
Q

Name some cross pollination implications

A

Outbreeding but more genetic variation
Less chance of harmful recessive alleles
allows species to survive in changing environments

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21
Q

How do plants ensure cross pollination?

A

Protandry- Stamen ripens before stigma
Protogyny- Stigma ripens before stamen
Anther is below stigma so pollen cannot fall onto it
genetic incompatibility- pollen cannot germinate on the flower which produced it
Separate male and female plants like holly

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22
Q

Why is double fertilisation called double fertilisation?

A

Because one fusion forms the zygote and another forms the endosperm

23
Q

Explain double fertilisation

A

Pollen grain lands on stigma+germinates in sucrose solution secreted by stigma and forms a pollen tube.
Pollen tube has tube nucleus at front and 2 generative nucleus behind.
The pollen tube grows out of the pollen grain via a pit towards chemo attractants.
The tube nucleus releases cellulases and proteases which hydrolyse the style, products are used for nutrients.
Pollen tube grows into embryo sac, tube nuclei disintegrates and generative nuclei are released.
1 nuclei fuses with oosphere forming the zygote, the other fuses with the polar nucleus forming a triploid nucleus which is the endosperm.

24
Q

What does the endosperm do after fertilisation?

A

It will divide by mitosis to produce endosperm tissues which is nutrients for zygote

25
Q

Where does a seed develop from?

A

From the fertilised ovule

26
Q

How does the seed develop?

A

After fertilisation, the diploid zygote divides by mitosis becoming an embryo which consists of the plumule, a radicle and 1 or 2 cotyledons.
Endosperm becomes food store
Outer integument dries out, hardens and becomes waterproof, this becomes the testa
The ovule becomes the seed
The funicle becomes the funicle of the seed attaching to it at the hilum
Ovary becomes the fruit.

27
Q

What is a plumule

A

The developing shoot, out of the ground

28
Q

What is the radicle?

A

The developing shoot, under the ground

29
Q

What is a cotyledon?

A

Seed leaves

30
Q

What is the food store for the embryo?

A

The endosperm which was produced by the fusion of 1 nuclei with the polar nucleus

31
Q

How is the testa/seed coat formed?

A

The ovule within the ovary dries out, hardens and becomes waterproof it has deposits of lignin. This layer is the Testa

32
Q

What is a micropyle

A

A pore in the seed

33
Q

What does the stalk/Funicle of the ovule become?

A

It becomes the funicle of the seed, it attaches to the seed at the hilum.

34
Q

What does the ovary become and give examples

A

The fruit
Cherry ovary becomes sweet
Almond ovary becomes dry and hard

35
Q

Where is the ovary located?

A

It is the outside layer, the testa is within the ovary.

36
Q

What does the ovary become in a broad bean after fertilisation?

A

ovary elongates into a pod which is the fruit

37
Q

Describe the structure of a dicotyledon and give an example

A

Broad bean
After fertilisation the ovary elongates into a pod which is the fruit. (outside layer)
The fruit contains several ovules which mature into seeds.

38
Q

What is germination?

A

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

39
Q

What are the 3 conditions for germination?

A

Temp- 5-30 for enzyme activity
Water- to mobilise enzymes for transport in xylem and phloem, and to make vacuole turgid
Oxygen- aerobic respiration releases energy, which fuels metabolism and growth

40
Q

Describe the process of mobilisation of food reserves.

A

Broad bean is a non-endospermic seed (endosperm absorbed into cotyledon).
Water is imbibed by the seed through the micropyle, this allows tissue to swell and provides conditions for enzyme activity.
Amylase hydrolyses starch within the cotyledon to maltose and proteases hydrolyse proteins to amino acids.
The soluble products are transported to embryo and carried by phloem to plumule/radical where cell division by mitosis occurs.
Some sugars are converted to cellulose for the cell wall, aerobic respiration releases energy from sugars and amino acids are used to make proteins.

41
Q

Describe the process of germination in a broad bean, after mobilisation.

A

Swollen tissues rupture the testa and the radicle emerges from the seed. The radicle is positively geotrophic and negatively phototropic so it grows downwards.
The plumule then emerges and grows upwards, it is bent like a hook as it pushes its way up the soil to protect the tip from soil abrasion.
Once emerged the plumule can photosynthesise and food reserves in cotyledon will be depleted.

42
Q

Over the course of germination what happens to the dry mass of seed, embryo and cotyledons?

A

The dry mass of the seed will increase, the dry mass of the embryo increases as it develops into a seedling.
The dry mass of the cotyledon will decrease as its providing food.

43
Q

What do the terms ‘malt’/’malting’ refer to?

A

They refer to the maltose generated when the starch in barley is digested

44
Q

Describe the effect of gibberellin in barley

A

The barley embryo secretes a plant growth regulator, gibberellic acid, this diffuses through the endosperm to aleurone layer.
The gibberellic acid switches on genes in the cells of the aleurone layer causing transcription + translation to produce the enzymes amylase/protease.
Proteases hydrolyse proteins to amino acids to make amylase.
The amylase diffuses out of aleurone and hydrolyses starch in endosperm.
The maltose and glucose produced diffuses to plumule and radicle.
They are respired for energy, this fuels biosynthesis and cell division bringing the seed out of dormancy.

45
Q

What is the name of a plant growth regulator?

A

Gibberellic acid

46
Q

Name some examples of how seeds survive

A

When dormant they have a low metabolic rate so they survive the winter
Testa physically protects the embryo
Dispersal for colonisation of new habitats
Testa is chemically resistant so seeds can survive chemical conditions

47
Q

What does non-endospermic mean?

A

When the food store/endosperm is absorbed into the cotyledons.
This happens in broad beans

48
Q

What does endospermic mean?

A

The food store/endosperm is not absorbed
This happens in cereal plants like maize

49
Q

What else happens to the testa in cereal crops?

A

The testa of the seed fuses with the ovary wall so they become one seeded fruits

50
Q

Name some differences in monocots to dictos

A

Monocots have leaf veins that are parallel
Dicots have leaf veins in a network
Monocots have sepals/petals/stamens in multiples of 3 where as dicots have them in multiples of 4/5
Monocots have vascular bundles scattered in roots and stems, dicots have them in a ring within stems and in the centre of roots

51
Q

What are some methods of seed dispersal?

A

Wind- dandelion
Transport- animals eating seeds which are digested and excreted
Water- coconut palm, carried away
Carrying- Burdock, has hooked seeds
Bursting- pea pod splitting open and seeds getting dispersed

52
Q

Where do monocots, like wheat and maize store their nutrients?

A

Endosperm

53
Q

Where do dicots store their nutrients?

A

Cotyledon

54
Q

What is the cell wall like in a fruit?

A

The testa and the ovary wall and fused.
In a seed you only have the testa

Biology (26 decks)

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