Reproduction in Plants (S) Flashcards

1
Q

What is the function of the flower

A

Sexual reproduction

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2
Q

Sexual reproduction

A

involves fusion of gametes from both parents

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3
Q

Carpel

A

Female reproductive organ

  • Stigma
  • Style
  • Ovary
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4
Q

Stamen

A

Male reproductive organ

  • Anther
  • Filament
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5
Q

Function of sepals

A

Protect the flower when in the bud

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6
Q

Function of petals

A

Attract animals

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7
Q

Function of stigma

A

Traps pollen

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8
Q

Function of style

A

Collects pollen

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9
Q

Function of ovary

A

Fertilisation becomes the fruit

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10
Q

Function of Anther

A

Pollen production and release

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11
Q

Function of Filament

A

Holds anther to release pollen

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12
Q

Function of Nectary

A

Produces nectar

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13
Q

Function of Receptacle

A

Floral parts arise from the receptacle

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14
Q

Female organ

A
  • Stigma, style, ovary
  • Egg cell (n)
  • 2 polar nuclei (n,n)
  • Collectively called 2 female gametes
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15
Q

How is the embryo sac formed?

A
  • Megaspore (mother cell) 2n divides by meiosis
  • Four haploid megaspores are formed (n)
  • 3 megaspores degenerate
  • Nucleus of the surviving megaspore divides by mitosis 3 times
  • Single-cell with eight nuclei is called the embryo sac
  • One nucleus develops the egg cell
  • Two nuclei become the polar nuclei
  • Female gametes are formed by meiosis followed by mitosis
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16
Q

What is produced by each fertilisation

A
  • Zygote

- Triploid endosperm nucleus

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17
Q

Male reproductive organ

A

Stamen

  • consists of anther and filament
  • Each pollen grain contains 2 male gametes
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18
Q

Outline how Pollen Grain is formed

A
  • Microspore mother cell (2n) divides by meiosis
  • produced 4 haploid cells which stick together to form a (tetrad)
  • Nucleus of each microspore (pollen grain) divides by mitosis
  • Forming tube and generative nucleus
  • Generative nucleus divides by mitosis forming the 2 male gametes, which appear as 2 nuclei
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19
Q

The mature pollen grain is surrounded by 2 walls

A
  • Tough outer exine

- Inner exine

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20
Q

Pollination

A

Transfer of pollen from the anther to the stigma

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21
Q

Self Pollination

A

Is formed when pollen is transferred from the anther to the stigma of the same flower to another flower
- occurs in cereal crops
-

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22
Q

Mechanism to prevent self-pollination

A

Carpel matures first so the plant can release its own pollen

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23
Q

Cross-Pollination

A

Pollen from the anther of one plant to the stigma of another plant of the same species

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24
Q

Mechanisms that prevent self-pollination

A

Greater variation

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25
Q

Name 2 methods of cross-pollination

A
  • Animals

- Wind

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26
Q

Methods of pollination in the flower

A

Animal: nectar to attract
Wind: Small

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27
Q

Methods of pollination in the pollen

A

Animal: large and sticky to attach to insects body
Wind: Small and dry which is easy to carry

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28
Q

Methods of pollination in the stigmas

A

Animal: sticky which forces insects to forage
Wind: Feathery which increases the surface area

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29
Q

Methods of pollination in the anthers

A

Animals: small inside flower which forces insect to forage
Wind: Large, outside flower which is an easy release of pollen

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30
Q

Hay fever

A
  • allergic reaction to inhaled allergens (pollen, dust)
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31
Q

Symptoms of hay fever

A
  • Inflammation of mucous

- blocked nose

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32
Q

Treatment for hay fever

A
  • Anti-histamines

- Decongestant to clear nasal

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33
Q

Define Fertilisation

A
  • Fusion of the male gamete with the female gamete to form a diploid zygote
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34
Q

Give an account for the lead up to double fertilisation

A
  • Pollen grains are transferred to stigma during pollination
  • Generative nucleus divides by mitosis forming the 2 male gametes
  • Pollen grain absorbs water and germinates to produce a pollen tube
  • The tube nucleus and the 2 male gametes move down into this pollen tube
  • The pollen tube grows down through the style and ovary tissue towards the embryo sac by the presence of chemotropism
  • The tube nucleus at the tip of the pollen tube controls and directs its growth
  • On reaching the micropyle, the pollen tube enters the embryo sac after which the tube nucleus degenerates
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35
Q

Outline what occurs during double fertilisation

A
  • 2 haploids make gametes enter the inside of the embryo sac where double-fertilisation occurs
  • One male gamete fuses with the egg cell forming a diploid zygote
  • A second male gamete fuses with the two polar nuclei to form a triploid endosperm nucleus
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36
Q

Events following fertilisation

A
  • Ovule becomes the seed
  • Integuments become the testa
  • Ovary becomes the fruit
  • Ovary wall becomes the fruit wall
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37
Q

What is testa

A

A tough hard seed that protects the seed

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38
Q

What is Helium

A

A scar is attached to the ovary wall

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39
Q

What is Micropyle

A

A pore

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40
Q

Radicle develops into

A

Develops into root

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41
Q

Plumule develops into

A

Develops into shoot

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42
Q

What are cotyledons

A

Seed leaves formed by some of the embryo cells
They contain food reserves that are used in the early stage of germination
They secrete enzymes that digest endosperm food, absorb it and pass it on to the developing embryo

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43
Q

Describe dicotyledonous seeds

A
  • 2 seed leaves
  • Non-endospermic seeds
  • Food store needed by the developing embryo is in the cotyledons
  • Biomolecules stored include lipids and proteins
  • Eg: Broad Bean
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44
Q

Describe Monocotoledonous seeds

A
  • 1 seed leaf
  • Seeds are endospermic
  • Food store needed by the developing embryo in the endospore
  • Biomolecules stored include lipids and proteins
  • Eg: Maize (not a typical monocot, stores its food in the cotyledon)
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45
Q

Fruit formation

A

Fertilised ovary becomes the fruit

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46
Q

Fruit formation is stimulated by

A

The release of auxin

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47
Q

Fruit functions include…

A
  • To aid seed dispersal

- Protect seeds

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48
Q

What is a false fruit

A

Do not develop from the ovary, but from other floral parts

eg: strawberries

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49
Q

Seedless fruits are produced by

A
  • Spraying flowers with auxins, before pollination and fertilisation
  • Breeding programmes
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50
Q

What is meant by seed dispersal

A

Scattering of seeds away from the parent plant

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51
Q

Advantages of seed dispersal

A
  • Reduces competition
  • Colonisation of favourable habitats
  • Better survival rate
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52
Q

Seed dispersal methods

A
  1. Wind
  2. Animals
  3. Water
  4. Self dispersal
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53
Q

How are seeds dispersed by the wind?

A

seeds are light and easier to disperse by the wind

eg: Dandelion

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54
Q

How are seeds dispersed by an animal?

A

Burdock clings to animal hair

Seeds egested

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55
Q

How are seeds dispersed by Water?

A

Floating on rivers or streams

eg: water lily

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56
Q

How are seeds dispersed by self dispersal?

A

Open scattering seeds under pressure

eg: peas

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57
Q

What is meant by seed dormancy?

A
  • Period when seeds undergo no growth and have reduced metabolism
58
Q

Advantages of seed dormancy

A
  • Germination is delayed until conditions are suitable
  • Embryo plant has more time to develop
  • More time for seed dispersal
59
Q

Causes of seed dormancy

A
  • By abscisic acid
  • when it’s broken down seeds can grow
  • Embryo is slow to develop due to lack of growth regulator
  • Regulator may be produced due to increased light or temperature
60
Q

Suggest why knowledge of dormancy is useful to humans

A
  • Knowledge of treatment of seeds before sowing
  • Correct environment for seed storage
  • Allows one to know when conditions are optimum for sowing seeds
61
Q

Special conditions may be needed to break seed dormancy before they are planted for use in horticulture

A
  • Soaking seeds in water
  • Exposure to light/dark
  • Exposure to cold temperatures
62
Q

Define seed germination

A

Regrowth of the embryo

63
Q

Factors needed for germination

A

Water (activate enzymes)
Oxygen (respiration)
Temperature (enzyme activity)

64
Q

List events during germination

A
  • Water is absorbed through the micropyle
  • Food stores are digested forming soluble nutrients
  • Soluble nutrients are transferred to the growing embryo
  • Regrowth of embryo
65
Q

Reason for water being absorbed through the micropyle

A
  • Activate enzymes to digest food
66
Q

Reason for food stores being forming soluble nutrients

A
  • Oils to fatty acids and glycerol
  • Starch to glucose
  • Proteins to amino acids
67
Q

Reason for soluble nutrients are transferred to the growing embryo

A
  • Embryo absorbs soluble nutrients
  • Glucose is used in aerobic respiration to provide energy
  • Amino acids are used to make enzymes
68
Q

Reason for regrowth of embryo

A
  • Radicle develops the root
  • Plumule develops the shoot
  • Once the first foilage leaves shoot can carry out photosynthesis producing glucose to sustain growth
69
Q

Events in seed germination

A

1- Water is absorbed
2- Stored food is digested
3- Digested food moves to embryo
4- Embryo grows

70
Q

Suggest why the measurement of dry mass is preferred in these investigations

A

As the water content can vary between different seeds

71
Q

Explain why the dry mass of the endosperm tissue decreases over the three weeks

A

Transfer of soluble nutrients to the embryo

72
Q

What process begins at A

A

Photosynthesis

73
Q

Would you expect the total dry mass of the seed to have remained the same up to A

A

No, will lose mass

Due to respiration

74
Q

Define dispersal in relation to seeds

A

Scattering seeds away from the parent plant

75
Q

Suggest 2 reasons why dispersal is important to plants

A

Reduces competition

Avoids overcrowding

76
Q

Give one way in which knowledge of seed dormancy is useful to plants

A

Gives knowledge to optimum sowing time

77
Q

Give 3 essential environmental; requirements for successful germination of seeds

A

Water
Oxygen
Temperature

78
Q

What is the role of digestion and the role of respiration in seed germination

A
  • Digestion
    To provide soluble nutrients for the embryo
  • Respiration
    Provides energy for the growth of an embryo
79
Q

Give a reason for the initial decrease in mass in the dry mass of peas

A

Respiration

80
Q

Give a reason for an increase in mass

A

Photosynthesis

81
Q

Name a substance that is responsible for the changes

A

Glucose

82
Q

Types of seedling growth

A

Cotyledons remain below soil or above the soil

83
Q

Example of cotyledons that remain below the soil

A

Broad bean

84
Q

Germination in the broad bean

A
  • cotyledons remain below the soil
  • elongation of the epicotyl at the base of the plumule occurs
    1. Seed absorbs water
    2. Radicle emerges
    3. A hooked plumule emerges
    4. The cotyledons remain underground
    5. Once above ground the plumule straightens
85
Q

Example of Cotyledons come above the soil

A

Sunflower

86
Q

Germination in the sunflower

A
  1. Seed absorbs water
  2. The radicle emerges
  3. Elongation of the hypocotyl
  4. Above the ground the cotyledons turn green and start photosynthesis as temporary seed leaves
87
Q

Give one disadvantage of self-pollination

A

Less genetic variation

88
Q

Give one-way seedless fruit may develop

A

Spray with growth regulators

89
Q

Define germination

A

Growth of seed into a plant

90
Q

Define dispersal

A

Scattering of seed away from the parent plant

91
Q

Define dormancy

A

Period of no growth

92
Q

Outline how dormancy in seeds benefits the plant species

A
  • will germinate when conditions are suitable

- allows the embryo to mature

93
Q

Give two roles of water in the process of germination

A
  • Softens seed coat
  • Activates enzymes
  • Increases metabolism
  • Transports nutrients
  • Dissolves nutrients
94
Q

Identify 2 possible food stores in seeds

A
  • Cotyledon

- Endosperm

95
Q

Which type of cell division occurs during the production of female gametes in

  • flowering plants
  • In humans
A
  • Meiosis followed by mitosis

- Meiosis

96
Q

Give one precise location of the production of the female gametes

  • flowering plants
  • In humans
A
  • Embryo sac

- Ovary

97
Q

Give one precise location of fertilisation under normal circumstances in

  • flowering plants
  • In humans
A
  • Embryo sac

- Fallopian tube

98
Q

Name the next stage of development following the formation of the zygote

  • flowering plants
  • In humans
A
  • Embryo

- Morula

99
Q

Give an advantage and a disadvantage of sexual reproduction in organisms

A
  • Increased genetic variation

- Two parents are needed

100
Q

Give fate of each male gametes

A

1 fuse together with the egg creating a zygote

1 fuse with the 2 polar nuclei creating endosperm

101
Q

Give a role for a petal

A

Attracts insects

102
Q

Give a role for an anther

A

Site of pollen production and release

103
Q

Give a role for stigma

A

Pollen lands on it during pollination

104
Q

Give one structure through which the pollen tube grows in order to reach the embryo sac

A

Through the style

105
Q

Within the pollen tube, the generative nucleus divides to form two male gametes what type of division takes place

A

Mitosis

106
Q

With what does each male gamete fuse in the embryo sac

A

Egg

2 polar nuclei

107
Q

Name the product of the fusion of male gamete and embryo sac

A

Zygote

Endosperm

108
Q

As the seed forms following fertilisation a food store develop in one of two structures. Name any of these structures

A

Cotyledon

Endosperm

109
Q

Name the site of production of a pollen grain

A

Anther

110
Q

Name the structure on which it must land to complete pollination

A

Stigma

111
Q

Name two methods of cross-pollination

A

Wind

Animal

112
Q

Advantage of self-pollination

A

Greater variation

prevents interbreeding

113
Q

Describe in detail the events that follow the arrival of a pollen grain at the anther up to and including fertilisation

A
  • Nucleus divides by mitosis forming 2 male gametes
  • Pollen grain absorbs water and germinates to produce a pollen tube
  • The tube nucleus and the 2 male gametes move down into this pollen tube
  • The pollen tube grows down through the style and ovary tissue towards the embryo sac by the process of chemotropism
  • On reaching the micropyle the pollen tube enters the embryo sac after which the tube nucleus degenerates
  • The 2 haploid male gametes enter the inside of the embryo sac where double-fertilisation occurs
  • One male gamete fuses with the egg cell forming a diploid zygote
  • Another male gamete fuses with the 2 polar nuclei forming a triploid zygote
114
Q

Which part of a flower usually develops into a fruit

A

Ovary

115
Q

Give role of sepals

A

Protect flower in bud

116
Q

Give a role of anther

A

Produce and release pollen

117
Q

Give a role of stigma

A

Traps pollen

118
Q

Describe the development of pollen grains

A
  • Microspore mother cell divides by meiosis
  • 4 haploid microspores stick together
  • The nucleus of each microspore divides by mitosis forming a cell with two haploid nuclei
  • The tube nucleus
  • Generative nucleus
  • The pollen grain is formed and becomes surrounded by 2 walls a tough outer exine and inner intine
  • Generative nucleus undergoes mitosis forming two male gametes
119
Q

What is meant by the term fertilisation?

A

Fusion of gametes to produce a zygote

120
Q

Give a brief account of fertilisation

A
  • Generative nucleus undergoes mitosis forming two male gametes
  • One male gamete fuses with an egg to form a zygote
  • Other male gamete fuses with the two polar nuclei to form endosperm
121
Q

Define dormancy

A

Period of reduced metabolism/ no growth in a seed

122
Q

Why is dormancy beneficial

A
  • Survival is delayed until conditions are suitable for growth
  • Greater time for embryo development
  • Reduced competition
123
Q

why is knowledge of dormancy beneficial for farmers

A
  • optimum storage conditions
124
Q

Effect of water on germination

A

For enzyme activation to digest food store

125
Q

Effect of suitable temperature on germination

A

Increased enzyme activity

126
Q

Effect of oxygen on germination

A

Needed for aerobic respiration

127
Q

Which part of the embryo in germinating seed gives rise to each of the following parts of the seed

  • the root
  • the shoot
A
  • Radicle becomes the root

- plumule become shoot

128
Q

Describe the digestive activity during the seed formation experiment

A
  • Soak 8 seeds overnight
  • Place on damp cotton wool
  • Label 2 starch agar plates
  • Kill half the seeds by boiling them
  • Use a flamed scalpel to cut the seeds lengthwise
  • Wash in a mild disinfectant solution to sterilise them and to prevent the growth of other micro-organisms
  • Using flamed forceps place 4 live seed halves with their plant embryo face down on starch agar
  • Repeat for the control but use 4 boiled seed halves
  • Both starch agar plates are immediately closed and left to stand at room temperature (20C) for 3-4 days
129
Q

Describe how you removed the seed halves from both plates and tested for starch

A
  • Pour dilute iodine over the surface of the starch agar in both plates
  • Allow to soak for two minutes and then pour off any excess
  • Observe the staining pattern
130
Q

What were the results of the experiment

A

Test plate: no blue-black under the seeds

Control plate: Under the seeds is blue-black

131
Q

Conclusion of the experiment

A

Test plate: Starch digestion takes place

Control: No statch digestion occurs

132
Q

What is an agar plate

A

A petri dish containing a gel-like or solid growth medium

133
Q

Why is digestion necessary in a germinating seed

A

To make nutrients soluble in the food reserve so it can be transferred to the growing embryo

134
Q

Name a part of a seed in which food for germination is stored

A

Cotyledon

135
Q

Why is it necessary to sterilise

A

To kill micro-organisms like bacteria and fungi

136
Q

How did you sterilise the seeds

A

Used disinfectant

137
Q

Name the substance that is used as a medium on which to germinate the seeds

A

Agar

138
Q

What substance to be digested by the seeds was added to the above medium

A

Starch

139
Q

What control did you use in this demonstration

A

Boiled seeds in the same set-up

140
Q

How did you demonstrate the digestive activity had taken place

A

Added iodine to test
It turned yellow-brown
No starch was present as it was digested by enzyme

141
Q

Describe the experiment in that you investigated the factors necessary for germination

A
  • Label Petri dishes
    A. No water
    B. Fridge
    C. Anaerobic
    D. Control
  • Place equal amounts of moist cotton wool in the base of dishes B-D
  • Add dry cotton wool to dish A
  • Place 10 radish seeds on the surface of the cotton
  • Set up a petri dish
    A. incubate at 25C for 4/5 days
    B. Leave in the fridge for 4/5 days
    C. Place petri dish inside an anaerobic jar containing an anaerobic chemical and incubate at 25C for 4/5 days
    D. This is the control plate as it has all the 3 factors present and incubate at 25C for 4/5 days
142
Q

Results of this experiment

A

Germination only occurred in the control dish

Each of the other dishes lacked one factor and failed to germinate