Reproduction in Plants (S) Flashcards
1
Q
What is the function of the flower
A
Sexual reproduction
2
Q
Sexual reproduction
A
involves fusion of gametes from both parents
3
Q
Carpel
A
Female reproductive organ
- Stigma
- Style
- Ovary
4
Q
Stamen
A
Male reproductive organ
- Anther
- Filament
5
Q
Function of sepals
A
Protect the flower when in the bud
6
Q
Function of petals
A
Attract animals
7
Q
Function of stigma
A
Traps pollen
8
Q
Function of style
A
Collects pollen
9
Q
Function of ovary
A
Fertilisation becomes the fruit
10
Q
Function of Anther
A
Pollen production and release
11
Q
Function of Filament
A
Holds anther to release pollen
12
Q
Function of Nectary
A
Produces nectar
13
Q
Function of Receptacle
A
Floral parts arise from the receptacle
14
Q
Female organ
A
- Stigma, style, ovary
- Egg cell (n)
- 2 polar nuclei (n,n)
- Collectively called 2 female gametes
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
16
Q
What is produced by each fertilisation
A
- Zygote
- Triploid endosperm nucleus
17
Q
Male reproductive organ
A
Stamen
- consists of anther and filament
- Each pollen grain contains 2 male gametes
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
19
Q
The mature pollen grain is surrounded by 2 walls
A
- Tough outer exine
- Inner exine
20
Q
Pollination
A
Transfer of pollen from the anther to the stigma
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
-
22
Q
Mechanism to prevent self-pollination
A
Carpel matures first so the plant can release its own pollen
23
Q
Cross-Pollination
A
Pollen from the anther of one plant to the stigma of another plant of the same species
24
Q
Mechanisms that prevent self-pollination
A
Greater variation
25
Name 2 methods of cross-pollination
- Animals
| - Wind
26
Methods of pollination in the flower
Animal: nectar to attract
Wind: Small
27
Methods of pollination in the pollen
Animal: large and sticky to attach to insects body
Wind: Small and dry which is easy to carry
28
Methods of pollination in the stigmas
Animal: sticky which forces insects to forage
Wind: Feathery which increases the surface area
29
Methods of pollination in the anthers
Animals: small inside flower which forces insect to forage
Wind: Large, outside flower which is an easy release of pollen
30
Hay fever
- allergic reaction to inhaled allergens (pollen, dust)
31
Symptoms of hay fever
- Inflammation of mucous
| - blocked nose
32
Treatment for hay fever
- Anti-histamines
| - Decongestant to clear nasal
33
Define Fertilisation
- Fusion of the male gamete with the female gamete to form a diploid zygote
34
Give an account for the lead up to double fertilisation
- 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
35
Outline what occurs during double fertilisation
- 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
36
Events following fertilisation
- Ovule becomes the seed
- Integuments become the testa
- Ovary becomes the fruit
- Ovary wall becomes the fruit wall
37
What is testa
A tough hard seed that protects the seed
38
What is Helium
A scar is attached to the ovary wall
39
What is Micropyle
A pore
40
Radicle develops into
Develops into root
41
Plumule develops into
Develops into shoot
42
What are cotyledons
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
43
Describe dicotyledonous seeds
- 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
44
Describe Monocotoledonous seeds
- 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)
45
Fruit formation
Fertilised ovary becomes the fruit
46
Fruit formation is stimulated by
The release of auxin
47
Fruit functions include...
- To aid seed dispersal
| - Protect seeds
48
What is a false fruit
Do not develop from the ovary, but from other floral parts
| eg: strawberries
49
Seedless fruits are produced by
- Spraying flowers with auxins, before pollination and fertilisation
- Breeding programmes
50
What is meant by seed dispersal
Scattering of seeds away from the parent plant
51
Advantages of seed dispersal
- Reduces competition
- Colonisation of favourable habitats
- Better survival rate
52
Seed dispersal methods
1. Wind
2. Animals
3. Water
4. Self dispersal
53
How are seeds dispersed by the wind?
seeds are light and easier to disperse by the wind
| eg: Dandelion
54
How are seeds dispersed by an animal?
Burdock clings to animal hair
| Seeds egested
55
How are seeds dispersed by Water?
Floating on rivers or streams
| eg: water lily
56
How are seeds dispersed by self dispersal?
Open scattering seeds under pressure
| eg: peas
57
What is meant by seed dormancy?
- Period when seeds undergo no growth and have reduced metabolism
58
Advantages of seed dormancy
- Germination is delayed until conditions are suitable
- Embryo plant has more time to develop
- More time for seed dispersal
59
Causes of seed dormancy
- 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
Suggest why knowledge of dormancy is useful to humans
- Knowledge of treatment of seeds before sowing
- Correct environment for seed storage
- Allows one to know when conditions are optimum for sowing seeds
61
Special conditions may be needed to break seed dormancy before they are planted for use in horticulture
- Soaking seeds in water
- Exposure to light/dark
- Exposure to cold temperatures
62
Define seed germination
Regrowth of the embryo
63
Factors needed for germination
Water (activate enzymes)
Oxygen (respiration)
Temperature (enzyme activity)
64
List events during germination
- 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
Reason for water being absorbed through the micropyle
- Activate enzymes to digest food
66
Reason for food stores being forming soluble nutrients
- Oils to fatty acids and glycerol
- Starch to glucose
- Proteins to amino acids
67
Reason for soluble nutrients are transferred to the growing embryo
- Embryo absorbs soluble nutrients
- Glucose is used in aerobic respiration to provide energy
- Amino acids are used to make enzymes
68
Reason for regrowth of embryo
- Radicle develops the root
- Plumule develops the shoot
- Once the first foilage leaves shoot can carry out photosynthesis producing glucose to sustain growth
69
Events in seed germination
1- Water is absorbed
2- Stored food is digested
3- Digested food moves to embryo
4- Embryo grows
70
Suggest why the measurement of dry mass is preferred in these investigations
As the water content can vary between different seeds
71
Explain why the dry mass of the endosperm tissue decreases over the three weeks
Transfer of soluble nutrients to the embryo
72
What process begins at A
Photosynthesis
73
Would you expect the total dry mass of the seed to have remained the same up to A
No, will lose mass
| Due to respiration
74
Define dispersal in relation to seeds
Scattering seeds away from the parent plant
75
Suggest 2 reasons why dispersal is important to plants
Reduces competition
| Avoids overcrowding
76
Give one way in which knowledge of seed dormancy is useful to plants
Gives knowledge to optimum sowing time
77
Give 3 essential environmental; requirements for successful germination of seeds
Water
Oxygen
Temperature
78
What is the role of digestion and the role of respiration in seed germination
- Digestion
To provide soluble nutrients for the embryo
- Respiration
Provides energy for the growth of an embryo
79
Give a reason for the initial decrease in mass in the dry mass of peas
Respiration
80
Give a reason for an increase in mass
Photosynthesis
81
Name a substance that is responsible for the changes
Glucose
82
Types of seedling growth
Cotyledons remain below soil or above the soil
83
Example of cotyledons that remain below the soil
Broad bean
84
Germination in the broad bean
- 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
Example of Cotyledons come above the soil
Sunflower
86
Germination in the sunflower
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
Give one disadvantage of self-pollination
Less genetic variation
88
Give one-way seedless fruit may develop
Spray with growth regulators
89
Define germination
Growth of seed into a plant
90
Define dispersal
Scattering of seed away from the parent plant
91
Define dormancy
Period of no growth
92
Outline how dormancy in seeds benefits the plant species
- will germinate when conditions are suitable
| - allows the embryo to mature
93
Give two roles of water in the process of germination
- Softens seed coat
- Activates enzymes
- Increases metabolism
- Transports nutrients
- Dissolves nutrients
94
Identify 2 possible food stores in seeds
- Cotyledon
| - Endosperm
95
Which type of cell division occurs during the production of female gametes in
- flowering plants
- In humans
- Meiosis followed by mitosis
| - Meiosis
96
Give one precise location of the production of the female gametes
- flowering plants
- In humans
- Embryo sac
| - Ovary
97
Give one precise location of fertilisation under normal circumstances in
- flowering plants
- In humans
- Embryo sac
| - Fallopian tube
98
Name the next stage of development following the formation of the zygote
- flowering plants
- In humans
- Embryo
| - Morula
99
Give an advantage and a disadvantage of sexual reproduction in organisms
- Increased genetic variation
| - Two parents are needed
100
Give fate of each male gametes
1 fuse together with the egg creating a zygote
| 1 fuse with the 2 polar nuclei creating endosperm
101
Give a role for a petal
Attracts insects
102
Give a role for an anther
Site of pollen production and release
103
Give a role for stigma
Pollen lands on it during pollination
104
Give one structure through which the pollen tube grows in order to reach the embryo sac
Through the style
105
Within the pollen tube, the generative nucleus divides to form two male gametes what type of division takes place
Mitosis
106
With what does each male gamete fuse in the embryo sac
Egg
| 2 polar nuclei
107
Name the product of the fusion of male gamete and embryo sac
Zygote
| Endosperm
108
As the seed forms following fertilisation a food store develop in one of two structures. Name any of these structures
Cotyledon
| Endosperm
109
Name the site of production of a pollen grain
Anther
110
Name the structure on which it must land to complete pollination
Stigma
111
Name two methods of cross-pollination
Wind
| Animal
112
Advantage of self-pollination
Greater variation
| prevents interbreeding
113
Describe in detail the events that follow the arrival of a pollen grain at the anther up to and including fertilisation
- 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
Which part of a flower usually develops into a fruit
Ovary
115
Give role of sepals
Protect flower in bud
116
Give a role of anther
Produce and release pollen
117
Give a role of stigma
Traps pollen
118
Describe the development of pollen grains
- 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
What is meant by the term fertilisation?
Fusion of gametes to produce a zygote
120
Give a brief account of fertilisation
- 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
Define dormancy
Period of reduced metabolism/ no growth in a seed
122
Why is dormancy beneficial
- Survival is delayed until conditions are suitable for growth
- Greater time for embryo development
- Reduced competition
123
why is knowledge of dormancy beneficial for farmers
- optimum storage conditions
124
Effect of water on germination
For enzyme activation to digest food store
125
Effect of suitable temperature on germination
Increased enzyme activity
126
Effect of oxygen on germination
Needed for aerobic respiration
127
Which part of the embryo in germinating seed gives rise to each of the following parts of the seed
- the root
- the shoot
- Radicle becomes the root
| - plumule become shoot
128
Describe the digestive activity during the seed formation experiment
- 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
Describe how you removed the seed halves from both plates and tested for starch
- 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
What were the results of the experiment
Test plate: no blue-black under the seeds
| Control plate: Under the seeds is blue-black
131
Conclusion of the experiment
Test plate: Starch digestion takes place
| Control: No statch digestion occurs
132
What is an agar plate
A petri dish containing a gel-like or solid growth medium
133
Why is digestion necessary in a germinating seed
To make nutrients soluble in the food reserve so it can be transferred to the growing embryo
134
Name a part of a seed in which food for germination is stored
Cotyledon
135
Why is it necessary to sterilise
To kill micro-organisms like bacteria and fungi
136
How did you sterilise the seeds
Used disinfectant
137
Name the substance that is used as a medium on which to germinate the seeds
Agar
138
What substance to be digested by the seeds was added to the above medium
Starch
139
What control did you use in this demonstration
Boiled seeds in the same set-up
140
How did you demonstrate the digestive activity had taken place
Added iodine to test
It turned yellow-brown
No starch was present as it was digested by enzyme
141
Describe the experiment in that you investigated the factors necessary for germination
- 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
Results of this experiment
Germination only occurred in the control dish
| Each of the other dishes lacked one factor and failed to germinate
