Pollination and Fertilization

Question 1

What are the functions of the following parts of the
flower:
* petals,
* stamen,
* pollen grains,
* stigma,
* ovary.

Answer 1

• petals – to attract pollinators
• stamen – to hold the (male) pollen in a position to be distributed – by pollinating insects or wind
• pollen grains – to carry male gametes to fertilise female gametes as so enable sexual reproduction
• stigma – to trap pollen grains and enable them to start the process of growing down to fertilize the (female) ovule
• ovary – the body which contains and protects the ovule/s and which in many cases becomes part of the fruit

Question 2

Bees and other pollinators fertilize flowers, enabling sexual reproduction to take place. What do bees and pollinators get in return?

Answer 2

Nectar and pollen, both of which are food sources for pollinators and their larvae.

Question 3

Name THREE plants which are wind-pollinated.

Answer 3

Maize (Zea mays)
English Oak (Quercus robur)
Willows (Salix spp.)

Question 4

What is cross-pollination and why do many plant
species try to ensure that it happens?

Answer 4

Cross-pollination is when a plant is able to fertilize another geneticallydifferent individual of the same species, i.e it is not fertilizing itself or a flower
of an individual of the same clone. The advantage for the plant species is that cross-pollination enables genetic re-combination and so the seed produced will be slightly different to that of both parents. This enables a population to be genetically active and continue to evolve, as natural selection will be able to operate on the resulting plants.

Question 5

Wild bees and other wild insect pollinators play an
essential role in the pollination of many food crops
and garden plants. Why can’t we rely simply on
domestic bees? What can we do to help benefit wild pollinator populations?

Answer 5

Domestic bees do not necessarily pollinate all flowers. Some flowers, particularly larger ones, are more likely to be pollinated by wild bees, e.g.
bumble bees.

Wild bees help pollinate many crops too. Wild bees and pollinators help ‘fill the gap’, for example if a bee hive were to be affected by disease or the impact of a bad winter, there may not be many bees around – wild bees will then play an important role in pollination.

Wild pollinator populations need a variety of flowers, so a high level of biodiversity is important, which means not just diverse gardens, but room for wild plants too. They need some uncultivated land, such as banks where small patches of bare soil are ideal places for them to make their nests.

Locations which are sheltered from strong or cold winds are good locations for all pollinators.

Question 6

Flowering times for apples

Answer 6

To ensure good pollination and therefore a good crop, it is essential to grow two or more different cultivars from the same Flowering Group or adjacent Flowering Groups.

Some cultivars are triploid – they have sterile pollen and need two other cultivars for good pollination; therefore, always grow at least two other nontriploid cultivars with each one.

Flowering Group 1
Very early; pollinated by groups 1 & 2
‘Gravenstein’ (triploid)

Flowering Group 2
Pollinated by groups 1,2 & 3
‘Baker’s Delicious’

Flowering Group 3
Pollinated by groups 2, 3 & 4
‘Acme’

Flowering Group 4
Pollinated by groups 3, 4 & 5
‘Gala’

Flowering Group 5
Pollinated by groups 4, 5 & 6
‘Coronation’

Flowering Group 6
Pollinated by groups 5,6 & 7
‘Bess Pool’

Flowering Group 7
Very late; pollinated by group 6
‘Crawley Beauty’

Question 7

What to know?

Answer 7

The agents of natural pollination are considered.

impact of temperature on the period of time that the stigma is responsive to pollen, along with the rate of growth of the pollen tube and the impact that this can have on fertilisation.

A similar level of detail can be applied to the impact of light levels, humidity and nutrition on
the processes of pollination and fertilisation.

• The importance of cross pollination in ensuring genetic diversity is considered along with examples of mechanisms within the plant to ensure this. Examples of such mechanisms could include pin and thrum eyed Primula vulgaris or the maturity of the male and female parts of the flower at different times.
• an understanding of the techniques used within horticulture to ensure pollination. Examples could include the use of windbreaks in fruit crops,
  the encouragement of pollinating insects, the use of bee species, i.e. boxes of bumblebees to ensure pollination of fruit in tunnels.

consider the impact of site selection criteria on pollination, the impact of frost pockets, wind, or existing vegetation. The identification and
impacts of microclimates on pollinator activity. The selection of suitable pollination partners, for example the concept of pollination tables, to
ensure compatibility of species when planning or planting a small fruit collection.

• investigate the impact of changes in invertebrate populations on pollination, and the role that gardens can have on boosting insect
  populations to enhance pollination and fertilisation.

Question 8

Define monoecious

Answer 8

Plants have male and female flowers: Cucurbita pepo - courgettes

Question 9

Define dioecious:

Answer 9

Have male and female flowers on separate plants:
Ilex aquifolium

Question 10

What is gamete?

Answer 10

Male: inside pollen grains on anthers
Female: found in ovules.

Question 11

What is pollen?

Answer 11

Grain like structure on tip of anther

Question 12

How does pollination occur?

Answer 12

Must be accepted by stigma thru correct chemical recognition.

Needs to be from same species or closely related

Ovule produces embryo of new plant, inc. into seed

Pollinators don’t deliberately pollinate (REWARD)

Design of flower all about attraction to make them brush past.

Question 13

What is cross pollination?

Answer 13

Pollen of 1 plant lands on stigma of another of same species.

Allows for genetic differences

Evolution of plant - better adapted to environment

Question 14

What is self pollination and is it good?

Answer 14

Does NOT bring new genetic material

Can occur ONLY with monoeicious plants (Helianthus annus or Solanum tuberosum)

Question 15

What is heterostly?

Answer 15

Structural variation in length of the style to ensure on the right pollen is accepted (preventing self-pollination).

Primula vulgaris

Question 16

What is distylous?

Answer 16

short and long style flowers and long/short anthers:

Primula vulgaris

Question 17

What are the advantages of self pollination

Answer 17

Self- pollination ensures that recessive characters are eliminated.

The wastage of the pollen grain is very less compared to cross-pollination

In the process of self- pollination, the purity of the race is maintained, as there is no diversity in the genes

In self- pollination, there is no involvement of external factors like wind, water, and other pollinating agents.

Self-pollination ensures that even a smaller quantity of produced pollen grains from plants have a good success rate in pollination.

Question 18

What are the disadvantages of self pollination

Answer 18

The major disadvantage of Self- pollination is there is no mixing up of genes. Due to which:

The vigour and vitality of the race are reduced
The immunity to diseases is reduced in the resultant offsprings.

Question 19

Advantages of cross pollination

Answer 19

The produced seeds are good in vigour and vitality.
All unisexual plants can reproduce through the process of Cross-pollination.
The recessive characters in the lineage are eliminated as a result of genetic recombination.
This process improves the immunity of the offsprings towards the diseases and other environmental factors.
Cross-pollination introduces new genes into a sequence of species and this is mainly due to the fertilization between genetically different gametes.

Question 20

Disadvantages of cross pollination

Answer 20

In this process, there is a great wastage of pollen grains.

Due to genetic recombination during meiosis, there are chances of eliminations of good qualities and additions of unwanted characteristics in offspring.

Question 21

How does temp affect pollination

Answer 21

Bees are weather dependent (esp. wild bees).

When temp and light levels are higher, flowers open/fade faster.

Stigma receptive for as shorter time

Temp at pollination time is signficant
Flowers need to be open

Insects and invertabrates need to be active

Only 1-2 days of warmth necessary for poll.

Question 22

What are pollination methods for insects?

Answer 22

PETALS: Lg and bright colour

SCENT/NECTAR: Usually scented with nectar

Pollen grains: Moderate - insects transfer efficiently.

Anthers: Located inside flower, stiff and firmly attached so poll. can brush by and pollen attaches

Stigma: Inside flower, sticky pollen grains,

EX: Helianthus annus, Primula vulgaris

Question 23

What are pollination methods for WIND

Answer 23

PETALS: small often dull, no attract nec.
SCENT/NECTAR: None
POLLEN GRAINS: smooth and light; easily carried by the wind w/clumping.
ANTHERS: OUTSIDE flower: loose on long filaments to release grains easily.
STIGMA: OUTSIDE of flower; feathery forms a network to catch drifting pollen grain

Examples: Zea mays; Taraxacum officinale

Question 24

What are pollination methods for WATER (hydrophily)

Answer 24

PETALS: -
SCENT/NECTAR: -
POLLEN GRAINS: Float on surface and drifts. Produce a large amount.
ANTHERS:
STIGMA: Large and feathery

Examples: Nymphaea

Question 25

Does light level matter for pollination

Answer 25

YES
Light pollution prevents nocturnal polls.
Low day light reduces
Influcences the size and number of flowers produced

Question 26

Does Relative Humidity affect poll?

Answer 26

YES
Influences insect flight and opening time of flowers.

Plant energy and transpiration also affected.

Question 27

Does weather make a difference?

Answer 27

YES
Insects do not fly well during rain/hail.
Flowers damaged.

Question 28

What are human factors affecting pollination?

Answer 28

Pruning - wrong time or technique

Planting - selection (mono/dio) density, habitat removal or not planted correctly (wind poll)

Protection of plants: netting etc.

Environments: barriers/greenhouses/covers

Chemicals: kill poll as well as pests.

Question 29

How to encourage pollinators?

Answer 29

rewilding
hedgerows
poll planting
Provide water and host sites
Avoid pesticides - NEVER spray on flowers
Avoid double or multi petalled flowers
Grow range of plants

Question 30

Seasonal choices for polls

Answer 30

WINTER: Clematis
SPRING: Primula vulgaris, Acer campestre
SUMMER: Centaurea cyanus
AUTUMN: Chrysanthemum or Dahlia

Question 31

How to integrate knowledge of poll of plants in hort

Answer 31

1. Put male dioecious plants windward side of fem.
2. Select sheltered area for wind protection
3. Plant extra poll species
4. Plant hedges/nests to enc. pollinators

Question 32

Implications of knowing poll. capacity

Answer 32

1. SP - produce more seed
2. CP become weedy and produce too many seedlings.
3. Create poll (and natural predator) microcliate to enourages poll.

Question 33

Describe pollination

Answer 33

Pollination is a crucial biological process in the reproduction of flowering plants (angiosperms). It involves the transfer of pollen, which contains male reproductive cells, from the anther (the male part of a flower) to the stigma (the female part of a flower) of a compatible flower. This transfer can occur within a single flower (self-pollination) or between different flowers of the same or different plants (cross-pollination).

There are various agents responsible for pollination:

Wind (Abiotic Pollination): Some plants rely on wind to carry their pollen from one flower to another. These plants typically have small, inconspicuous flowers and produce large quantities of lightweight, easily-dispersed pollen. Examples include grasses, many trees like oaks and pines, and some flowers like ragweed.

Insects (Entomophily): Insects, such as bees, butterflies, moths, and beetles, are among the most common pollinators. They are attracted to flowers by their bright colors, patterns, and sweet nectar. As they forage for nectar, pollen adheres to their bodies and is transported to other flowers they visit.

Birds (Ornithophily): Some bird species, like hummingbirds, sunbirds, and honeyeaters, are specialized pollinators. They are attracted to brightly colored, tubular flowers that are often red or orange. As they feed on nectar, their heads come into contact with the flower’s reproductive structures, facilitating pollen transfer.

Bats (Chiropterophily): In some parts of the world, especially in tropical regions, bats play a vital role as pollinators. They are attracted to night-blooming, fragrant flowers. As they feed on nectar, pollen is transferred from the flower to the bat and subsequently to other flowers.

Other Animals: Besides insects, birds, and bats, there are other animals like small mammals, reptiles, and even some larger insects like flies that can act as pollinators for certain plant species.

Successful pollination is essential for plants to produce fruits and seeds. These fruits serve as a means of protecting and nourishing the developing seeds, and they also play a crucial role in seed dispersal, allowing plants to colonize new areas.

Overall, pollination is a complex and vital ecological process that supports the reproduction and survival of a wide variety of plant species, and it also indirectly sustains many animal species that depend on these plants for food and habitat.

Question 34

Describer fertilization

Answer 34

Fertilization in plants is the process by which male and female reproductive cells (gametes) combine to produce a zygote, which eventually develops into a new individual plant. This process occurs after successful pollination.

Here’s a step-by-step description of fertilization in angiosperms (flowering plants):

Pollination: Before fertilization can occur, pollen must be transferred from the anther (male reproductive organ) of one flower to the stigma (female reproductive organ) of a compatible flower. This can be achieved through various means, including wind, insects, birds, or other animals.

Germination of Pollen Grain: Once a pollen grain lands on a receptive stigma, it absorbs water and germinates. This involves the formation of a pollen tube, which grows down through the style (the stalk-like structure connecting the stigma to the ovary).