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Biology > Sexual & Asexual Reproduction In Plants (chpt. 39 & 40) > Flashcards

Sexual & Asexual Reproduction In Plants (chpt. 39 & 40) Flashcards

1
Q

Female parts of plant

A

Carpel
• stigma
• style
• ovary

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2
Q

Male parts of plant

A

Stamen

• anther
• filament

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3
Q

Role of stigma

A

Captures pollen

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4
Q

Role of style

A

Connects stigma to ovary

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5
Q

Role of ovary

A

Site of fertilisation , produces the ovule

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6
Q

Role of anther

A

Produces male gametes (pollen grains)

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7
Q

Role of filament

A

Supports anther and supplies it with food and water

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8
Q

Role of sepal

A

Protects the bud

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9
Q

Role of petal

A

Attract animal pollinators
↳ brightly coloured and scented

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10
Q

Where are the male gametes found?

A

In the pollen grains

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11
Q

Male gamete formation → steps

A

• anther consists of 4 pollen sacs containing diploid microspore mother cells
• divide by meiosis to produce 4 haploid cells which join to form tetrad
• tetrad breaks up and forms 4 microspores
• microspore divides by mitosis to produce 2 haploid nuclei → generative nucleus and tube nucleus

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12
Q

Female gamete formation → steps

A

• diploid megaspore mother cell in ovule divides by meiosis to produce 4 haploid cells → 3 degenerate and 1 survives as megaspore / embryo sac
• embryo sac undergoes mitosis 3 more times to produce 8 haploid nuclei → 5 die, 2 form polar nuclei, 1 forms egg

Female gametes: 1 egg + 2 polar nuclei

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13
Q

Pollination

A

Transfer of pollen from an anther to a stigma of a flower of the same species

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14
Q

Cross-pollination

A

Pollination of another plant of the same species

↳ more variation & greater strength

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15
Q

Self-pollination

A

Pollination of a plant by itself

↳ less variation

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16
Q

Features of an animal pollinated plant

A

Large bright scented petals

Sticky stigma

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17
Q

Features of a wind pollinated plant

A

Large quantity of light pollen produced
Long stamen outside flower
Long feathery stigma

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18
Q

Fertilisation

A

The fusion of male and female gametes to form a diploid zygote

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19
Q

Steps in fertilisation

A

• pollen grain lands on stigma
• tube nucleus forms pollen tube which grows down the style to the ovule
• generative nucleus divides by mitosis to form 2 sperm nuclei
• double fertilisation occurs:
Sperm nucleus + egg nucleus → zygote (2n)
Sperm nucleus + 2 polar nuclei → endosperm (3n)

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20
Q

Which part of seed develops into the shoot?

A

Plumule

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21
Q

Which part of seed develops into the root?

A

Radicle

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22
Q

Function of testa

A

Protects embryo

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23
Q

Function of cotyledon

A

Food storage + seed leaves

24
Q

Function of embryo

A

Develops into a new plant

25
Q

Steps in seed growth

A

• water softens testa & activates enzymes within the seed
• stored foods are digested by embryo to form new structures
• radicle grows & bursts out of testa
• plumule emerges above ground and leaves start to form

26
Q

From what structure in the seed does fruit develop?

A

The ovary

27
Q

Function of fruit

A

Protect seeds , allow dispersal

28
Q

How is seedless fruit produced?

A

Can be formed by genetically breeding seedless varieties

29
Q

Dispersal

A

The transfer of a seed or fruit away from the parent plant

30
Q

Benefits of dispersal

A

• minimises chance of overcrowding and competition
• allows plants to grow in new areas
• increases number of species

31
Q

Example of: wind dispersal

A

Winged fruits & seeds e.g. sycamore

32
Q

Example of: water dispersal

A

Floating fruit e.g. coconut

33
Q

Example of: animal dispersal

A

Edible fruits eaten by animals and pass through digestive system, deposited away from parent plant e.g. acorns

34
Q

Example of: self-dispersal

A

Dehiscent fruits have an explosive mechanism e.g peas

35
Q

Dormancy

A

Resting period when seeds undergo no growth and have reduced cell activity or metabolism

36
Q

Causes of dormancy

A

• growth inhibitors
• testa may be impermeable to water or oxygen
• testa maybe too hard for embryo to emerge
• lack of growth regulator

37
Q

Dormany in agriculture & horticulture

A

Some seeds need a long cold period to bring on germination
Dormancy can be broken by:
→ soaking seeds in water
→ exposing seeds to light or dark
→ exposing seeds to cold temperature

38
Q

Advantages of dormancy

A

• allows seeds to avoid harsh conditions
• allows time for dispersal
• allows time for immature embryo to develop
• maximises the growing season

39
Q

Germination

A

The regrowth of the embryo after a period of dormancy if the environmental conditions are suitable

40
Q

Condition necessary for germination

A

Water → for enzyme activity
Oxygen → respiration
Suitable temperature → effects germination

41
Q

Events in germination

A

• water absorbed through micropyle in testa
• stored food is digested
• digested food moves to the embryo
• embryo grows
• food used in respiration (dry mass falls)
• radicle bursts through testa
• plumule emerges above ground & leaves are produced
• when leaves start to photosynthesise, dry mass increases

42
Q

Hypogeal germination

A

Cotyledon remains below the soil e.g broad bean

43
Q

Epigeal germination

A

Cotyledons rise above ground e.g sunflower

44
Q

Vegetative propagation

A

Asexual reproduction in plants

45
Q

Asexual reproduction

A

Production of organisms from only one parent

46
Q

Example of a modified bud

A

E.g. garlic

47
Q

Example of modified leaves

A

E.g cacti

48
Q

Example of a modified overground stem

A

Runners, e.g strawberry

49
Q

Example of modified roots

A

Tap roots - swollen main roots, e.g carrot

50
Q

Methods of artificial vegetative propagation

A
  1. Cuttings e.g busy - lizzie
  2. Grafting e.g apples
  3. Budding e.g roses
  4. Micropropogation (tissue culture) e.g commercial crops → bananas, strawberries
51
Q

Advantages of asexual reproduction

A

• rapid growth due to maturity
• simple & reliable process
• not dependent on external agents for pollination, fertilisation or seed dispersal
• no waste

52
Q

Disadvantages of asexual reproduction

A

• no variation
• overcrowding & competition
• one disease can wipe out all plants
• no seeds formed

53
Q

Advantages of sexual reproduction

A

• seeds show variation
• wide dispersal due to seeds and fruits
• some plants may be resistant to disease
• dormancy allows survival in adverse conditions

54
Q

Disadvantages of sexual reproduction

A

• plants may take years to develop
• complex process
• depends on external agents
• wastage of fruit / seed by being eaten, disease etc

55
Q

What is a seed?

A

A fertilised ovule

Biology (34 decks)

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