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WJEC A2 Biology > Plant Reproduction- Unit 4.2 > Flashcards

Plant Reproduction- Unit 4.2 Flashcards

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1
Q

Describe the petals on an insect pollinated plant and a wind pollinated plant:

A

Insect- Large, bright & scented.
Wind- Small, dull & no scent.

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2
Q

Which type of flower has nectar and which does not?

A

Does- Insect
Doesn’t- Wind

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3
Q

How much pollen is present in insect & wind pollinated plants?

A

Insect- moderate quantity
Wind- great quantity

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4
Q

What is the pollen texture of wind & insect pollinated flowers?

A

Wind- light & smooth to avoid clumping and can be blown in wind.
Insect- Sticky/spiky to stick to insects.

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5
Q

Where are the anthers located in the two types of flower?

A

Insect- firm & inside to brush against insects.
Wind- loosely attached and dangle to release pollen into wind.

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6
Q

Describe the stigma positioning between insect and wind pollinated plants:

A

Insect- inside flower so insects brush against it & is sticky.
Wind- hangs outside to catch drifting pollen & is feathery.

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7
Q

What are the advantages of self-pollination?

A

•Better preservation of beneficial genomes suited to a relatively stable environment.

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8
Q

What are the disadvantages of self pollination?

A

•Display less generic variation.
•Greater chance of deleterious recessive alleles.

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9
Q

Advantages of cross pollination:

A

•Great variation.
•Reduced risk of deleterious recessive alleles and causing harmful combinations.
•Increased chance of survival (natural selection)

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10
Q

What are the methods to avoid self-fertilisation?

A

Dioecious
Protandry
Genetic incompatibility
Protogyny

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11
Q

What does dioecious mean?

A

Separate male and female individuals

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12
Q

What does protandry mean?

A

Pollen matures first

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13
Q

What is genetic incompatibility?

A

Several genetic mechanisms which prevents self-fertilisation and thus encouraging outcrossing.

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14
Q

What is protogyny?

A

Ovules mature first

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15
Q

What does angiosperm mean?

A

A large group of plants that produce flowers, seeds & fruits.

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16
Q

What is a receptacle?

A

Thickened part of stem where flower organs grow

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17
Q

What is the calyx?

A

the collective name of the sepals

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18
Q

What is the sepal?

A

Green parts that protect the flower bud and extend from the base of a flower after it has opened.

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19
Q

What is a corolla?

A

The collective name of the petals

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20
Q

Describe the petal:

A

Modified leaves that surround the reproductive flowers.

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21
Q

What is the stamen?

A

The male reproductive organ in angiosperms
(anther & filament)

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22
Q

What is the filament?

A

Stamen structure that supports anther.

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23
Q

What is an anther?

A

Stamen structure which produces the pollen

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24
Q

What is pollen?

A

Male gamete in angiosperms

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25
Q

What is a carpel?

A

Female reproductive organ in angiosperms
(stigma, style & ovary)

26
Q

What is the ovary in plant?

A

Part of the pistil which holds the ovules. It is located above/below/at point of connection with the base of the petals and sepals.

27
Q

What is the ovule?

A

Female gamete in angiosperms

28
Q

What is the style?

A

Long, slender stalk which connects stigma and ovary.

29
Q

What is the stigma?

A

Receives pollen at pollination and is the place where pollen grains germinates, often sticky.

30
Q

What is the nectary?

A

An organ/part of plant which secretes nectar & attractive scent

31
Q

What is chemical self-incompatibility? (ensuring some degree of cross-pollination)

A

Pollen will not germinate on the stigma of same flower as chemical signals produced by stigma do not stimulate pollen from same flower.

32
Q

How does flower structure ensure cross-pollination?

A

The arrangement of anthers and stigmas can force cross-pollination, or even self-pollination.
Flowers with irregular structure force insects to have to enter in a particular way, decreasing likelihood of self-pollination.

33
Q

How does the development of anthers and stigmas reduce self-pollination?

A

Either the anthers or stigmas will mature before the other so that pollen cannot be present at the same time as the stigma in the same flower.

34
Q

Describe the process of ovule formation:

A
  1. megaspore mother cell (diploid)
  2. meiosis x2, produces 4 genetically different daughter cells.
  3. 3/4 cells degenerate.
  4. mitosis x3, produces 8 genetically identical nuclei. (haploid)
  5. nuclei formed into 3 antipodal cells, 2 synergids, 2 polar nuclei & 1 ovum.
35
Q

What must occur before fertilisation takes place?

A

Pollination

36
Q

What is germination?

A

The development of a plant from a seed to a young plant/seedling

37
Q

What are the style and ovary wall digested by?

A

Hydrolase enzymes

38
Q

What is double fertilisation?

A

The fusion of the egg and sperm:
the simultaneous fusion of a second sperm and two polar nuclei that ultimately results in the formation of the endosperm.

39
Q

What is an endosperm?

A

The part of the seed which acts as a food store for the developing embryo.
Usually contains starch, protein and other nutrients

40
Q

Pollination definition:

A

The transfer of pollen from a male anther to the female stigma. This happens to allow fertilisation.

41
Q

What conditions are required for germination to take place?

A

•Absorb water through micropyle.
-mobilises enzymes, transports materials in seeds & increases cell size due to vacuoles forming which split tests.
•Absorb oxygen through micropyle for aerobic respiration.
•Optimum temperature.
•Some require light.

42
Q

What are endospermic seeds?

A

Seeds that have an endosperm

43
Q

What is the radicle?

A

The first part of the seedling to grow to absorb water and minerals from soil. (developing root)

44
Q

What is the epicotyl?

A

The stem of the plumule which elongates due to vacuolation of the cells and pulls the leafs backwards through the soil.

45
Q

How is a pollen grain developed?

A

-Pollen sac contains diploid mother pollen cells.
-These divide by meiosis, creating a tetrad. (4 haploid microspores)
-These develop into pollen grains.
-Mitosis occurs in the pollen grain, producing a generative nucleus (will form 2 male nuclei later) and a pollen tube nucleus.
-Edges of pollen sacs curl after anthers have dried once pollen grain is ripe, exposing pollen grains. They can now be carried away.

46
Q

What is a pin-eyed flower?

A

Stigma above stamens to prevent self pollination.

47
Q

What is a thrum eyed flower?

A

If pollen falls onto stigmas, it will not germinate. If self-pollination occurs, there is a mechanism to prevent successful fertilisation and seed production.

48
Q

Explain fertilisation: (10)

A
  1. Pollen grain lands on stigma, absorbs water & germinates, producing pollen tube.
  2. 3 nuclei present in pollen tube. (tube nucleus & 2 nuclei behind)
  3. Pollen tube grows out of pollen grain through pit.
  4. Tube nucleus releases digestive enzymes to digest tissues of style, making way for pollen tube.
  5. Ovule releases chemoattractants, providing gradient for pollen tube to grow up.
  6. It reaches ovary & enters embryo sac via micropyle.
  7. Pollen tube nucleus disintegrates, tip opens, 2 nuclei enter embryo sac.
  8. First one fuses with egg nucleus to form diploid zygote.
  9. This undergoes mitosis to become embryo of seed.
  10. Second one fuses with diploid polar nucleus, forming triploid endosperm nucleus. (food store)
    DOUBLE FERTILISATION HAS OCCURRED.
49
Q

What is a micropyle?

A

A gap in integuments (protective layer surrounding ovule)

50
Q

What is a cotyledon?

A

Seed leaves

51
Q

What is a plumule?

A

Developing shoot

52
Q

What does the seed develop from?

A

Fertilised embryo, endosperm and testa.
(the ovule)

53
Q

What does the fertilised embryo consist of?

A

Radicle, cotyledon 1/2) & plumule

54
Q

How are the seeds and fruit developed after fertilisation?

A

Triploid endosperm nucleus divides by mitosis, forming endosperm tissue. These become filled with stored food for embryo.
Outer integument dries out, hardens & becomes waterproof using deposits of lignin.
This becomes the testa (seed coat).
The ovule becomes the seed and the ovary becomes the fruit

55
Q

What are non-endospermic plants?

A

Plants which do not have an endosperm as it is absorbed in early stages of seed development. The food is stored in the cotyledons instead.

56
Q

What are dicot’s?

A

-2 cotyledons in seed.
-Leaf veins form network
-Sepals, petals & stamens in multiples of 4/5.
-Vascular bundles arranged in ring

57
Q

What are monocot’s?

A

-1 cotyledon in seed.
-Leaf veins are parallel.
-Sepals, petals & stamens in multiples of 3.
-Vascular bundles scattered.

58
Q

Why is dispersal of the seed far away from the parent plant important?

A

To reduce competition with parent plants.
The further the dispersal, the greater the success of obtaining water & minerals from soil, as well as adequate sunlight.

59
Q

Name the different dispersal methods:

A

-Wind (parachute/pores that wind spreads)
-Transport (in faeces after being eaten)
-Rolling (fall)
-Bursting (burst so scatter when dry)
-Water (float)
-Carrying (hooks attaching to animals)

60
Q

What are some adaptations that seeds have?

A

-Dormant seeds have low metabolic rate so can survive in cold conditions.
-Testa is chemically resistant.
-Water content below 10% so can survive in dry conditions.
-Seeds dispersed at great distances.

WJEC A2 Biology (12 decks)

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