Fertilisation and seed formation

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Lesson notes

Pollination and Fertilisation

**Fertilisation** occurs after successful **pollination**.
Pollination is when pollen from the **stamen** (male part) reaches the **carpel** (female part) of a flower.
After landing on a **stigma**, a pollen grain germinates and grows a **pollen tube** down the **style** to the **ovary**.
The male sex cell nucleus moves through the pollen tube and joins with the **ovule** nucleus – this joining is **fertilisation**.

Seed Formation

The fertilised **ovule** becomes a **seed**.
Each seed contains an **embryo plant** and a **food store** to nourish it.
The seed is protected by a **seed coat**.

Fruit Formation

As seeds develop, the **ovary** transforms into a **fruit**.
The fruit protects the seeds and helps in their **dispersal**.
Fruits include **berries**, **nuts**, and **pods**.

Importance of Insect Pollinators

Many crops (fruits, vegetables, nuts) depend on **insect pollination** by bees, butterflies, and beetles.
Pollinators transfer pollen between flowers, enabling seed and fruit production.
Without insect pollination, **crop yields** would decrease, reducing food availability and increasing prices.
This affects **global food security** – the quantity and diversity of food.

Diagram showing pollen tube growth and fertilisation in a flower.

Structure of a seed showing seed coat, embryo, and food store.

Slides

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Practice questions

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1.Which of the following is the male part of a flower?
Easy
- AStamen
- BCarpel
- COvary
- DStigma
2.Fertilisation in plants occurs when which two nuclei join?
Easy
- AMale sex cell nucleus and ovule nucleus
- BPollen nucleus and stigma nucleus
- CSperm nucleus and egg nucleus
- DMale nucleus and female nucleus
3.Which part of the flower develops into a fruit after fertilisation?
Medium
- AOvary
- BOvule
- CStigma
- DStyle
4.What is the role of the pollen tube in plant fertilisation?
Medium
- AIt transports the male sex cell to the ovule
- BIt produces pollen grains
- CIt receives pollen from the anther
- DIt becomes the seed coat
5.Which of the following is NOT a part of a seed?
Hard
- AAnther
- BEmbryo plant
- CFood store
- DSeed coat
6.If bee populations decline significantly, what is the most likely effect on crop yields?
Hard
- ACrop yields would decrease
- BCrop yields would increase
- CCrop yields would stay the same
- DCrop yields would become more variable
7.The anther and filament are parts of which flower structure?
Medium
- AStamen
- BCarpel
- CPetal
- DSepal
8.What is the function of the seed coat?
Medium
- ATo protect the seed
- BTo provide food for the embryo
- CTo attract pollinators
- DTo help in seed dispersal

More questions

9.Which of the following is an example of a fruit?
Hard
- AA pea pod
- BA potato
- CA carrot
- DA lettuce leaf
10.What would be the most likely consequence of a decline in insect pollinators for food prices?
Hard
- AFood prices would increase
- BFood prices would decrease
- CFood prices would remain unchanged
- DFood prices would become more stable
11.The diagram shows a flower. Which labelled part is the stigma?
Medium
- AA
- BB
- CC
- DD
12.What is the first step in the process of fertilisation in plants?
Easy
- APollination
- BGermination of the pollen grain
- CGrowth of the pollen tube
- DJoining of nuclei
13.Which part of the flower becomes the seed after fertilisation?
Easy
- AOvary
- BOvule
- CStigma
- DStyle
14.A farmer notices that a field of apple trees has produced very few apples. Which of the following is the most likely cause?
Medium
- AThe trees were over-watered
- BThere were few insects pollinating the flowers
- CThe soil lacked nitrogen
- DThe trees were planted too close together
15.In a plant species, the pollen tube grows at a rate of 0.5 mm per hour. If the distance from the stigma to the ovule is 12 mm, how many hours does it take for the pollen tube to reach the ovule?
Medium
- A6 hours
- B12 hours
- C24 hours
- D48 hours
16.The table below shows the number of seeds produced per flower in two plant species, one insect-pollinated and one wind-pollinated. Which row is most likely correct?
Hard
- AInsect-pollinated: 50 seeds per flower; Wind-pollinated: 100 seeds per flower
- BInsect-pollinated: 100 seeds per flower; Wind-pollinated: 50 seeds per flower
- CInsect-pollinated: 10 seeds per flower; Wind-pollinated: 10 seeds per flower
- DInsect-pollinated: 200 seeds per flower; Wind-pollinated: 200 seeds per flower
17.A scientist measures the number of fruits produced per plant in two fields: one with bees and one without bees. The results are shown in the graph. Which conclusion is supported by the data?
Hard
- ABees have no effect on fruit production
- BThe presence of bees increases fruit production
- CThe presence of bees decreases fruit production
- DBees only affect the size of fruits, not the number
18.What is the function of the food store in a seed?
Easy
- ATo attract pollinators
- BTo protect the seed from predators
- CTo nourish the embryo as it grows
- DTo help in seed dispersal
19.In a greenhouse, a farmer uses artificial pollination to ensure fruit set in tomato plants. However, the fruits are smaller than those from bee-pollinated plants outdoors. What is the most likely reason?
Hard
- AArtificial pollination does not transfer enough pollen
- BBee-pollinated plants receive more water
- CTomato plants cannot set fruit without bees
- DOutdoor plants have more nutrients
20.The stamen is made up of which two parts?
Easy
- AAnther and filament
- BStigma and style
- COvary and ovule
- DPetal and sepal
21.The diagram shows a seed. Which labelled structure is the food store?
Medium
- AA
- BB
- CC
- DD
22.A student investigates the effect of temperature on pollen tube growth. They place pollen grains on a stigma and measure the length of the pollen tube after 24 hours at different temperatures. Which variable should they control to ensure a fair test?
Medium
- ATemperature
- BType of flower
- CLength of pollen tube
- DTime of day
23.A scientist observes that a population of bees decreases by 30% due to pesticide use. In the same area, the yield of insect-pollinated crops decreases by 25%. Which of the following is the most likely conclusion?
Hard
- AThe decrease in bee population caused the decrease in crop yield.
- BThe decrease in crop yield caused the decrease in bee population.
- CPesticides directly reduced crop yield, not bee population.
- DThere is no relationship between bee population and crop yield.
24.A student sets up an experiment to test whether the presence of bees increases fruit production in strawberry plants. They have two groups: one group of plants is covered with a net to exclude bees, and the other group is left uncovered. After flowering, they count the number of fruits per plant. Which of the following is an appropriate control?
Medium
- ACover both groups with nets.
- BLeave both groups uncovered.
- CUse the same variety of strawberry for both groups.
- DCount the number of flowers before the experiment.
25.In an experiment, pollen grains from a wind-pollinated plant are placed on the stigma of an insect-pollinated plant. Which of the following is the most likely outcome?
Hard
- AFertilisation will occur because pollen is pollen.
- BFertilisation will not occur because the pollen is not adapted to stick to the stigma.
- CThe pollen tube will grow but the nuclei will not fuse.
- DThe stigma will reject the pollen and no pollen tube will form.
26.Which of the following is the correct order of events in plant reproduction?
Easy
- APollination → fertilisation → seed formation → fruit formation
- BFertilisation → pollination → seed formation → fruit formation
- CPollination → fruit formation → fertilisation → seed formation
- DSeed formation → pollination → fertilisation → fruit formation
27.A scientist measures the number of fruits produced per plant in two fields: one with bees and one without bees. The results are shown in the graph. Which conclusion is best supported by the data?
Hard
- ABees increase fruit production by 50%.
- BWithout bees, fruit production is zero.
- CBees are essential for fruit production in this plant.
- DThe plant can produce some fruit without bees, but bees increase yield.
28.A student wants to observe pollen tube growth. They place pollen grains on a glass slide with a sugar solution and observe under a microscope. Which of the following is a valid control for this experiment?
Medium
- AA slide with pollen grains but no sugar solution
- BA slide with sugar solution but no pollen grains
- CA slide with pollen grains and distilled water
- DA slide with pollen grains and salt solution
29.In a greenhouse, a farmer uses artificial pollination to ensure fruit set in tomato plants. However, the fruits are smaller than those from bee-pollinated plants. Which of the following is the most likely explanation?
Hard
- AArtificial pollination transfers less pollen than bees.
- BBees carry a different type of pollen.
- CThe artificial method damages the ovules.
- DBee-pollinated flowers produce more seeds, leading to larger fruits.
30.What is the male part of a flower called?
Easy
- AStamen
- BCarpel
- CStigma
- DOvary
31.After pollination, what structure grows from the stigma to the ovary?
Easy
- APollen tube
- BStyle
- CFilament
- DSeed coat
32.Which of the following is the male part of the flower?
Easy
- AStamen
- BCarpel
- CStigma
- DOvary
33.A scientist measures the number of fruits produced per plant in two fields: one with bees and one without bees. The results are shown in the table. Which conclusion is supported by the data? Field A (with bees): 150 fruits per plant Field B (without bees): 20 fruits per plant
Hard
- ABees increase fruit production
- BBees decrease fruit production
- CBees have no effect on fruit production
- DBees only affect nut crops
34.In a greenhouse, a farmer uses artificial pollination to ensure fruit set in tomato plants. However, the fruits are smaller than those from bee-pollinated plants. What is the most likely explanation?
Medium
- AArtificial pollination may not transfer enough pollen or may not stimulate full fruit development
- BArtificial pollination adds chemicals that reduce fruit size
- CBee-pollinated plants receive more water
- DTomatoes cannot be artificially pollinated
35.A student investigates the effect of temperature on pollen tube growth. They place pollen grains on a stigma and measure the length of the pollen tube after 24 hours at different temperatures. Which of the following would be a suitable control variable?
Medium
- AType of plant
- BTemperature
- CLength of pollen tube
- DTime of day
36.A scientist observes that a population of bees decreases by 30% due to pesticide use. In the same area, the yield of insect-pollinated crops decreases by 25%. What can be inferred?
Hard
- AThere is a correlation between bee population and crop yield
- BPesticides directly increase crop yield
- CBee decline has no effect on crop yield
- DThe crop yield decrease is due to lack of water
37.The diagram shows a flower. Which labelled part is the stigma? (Diagram: icon_scene with a flower, labels pointing to parts)
Easy
- AThe top part of the carpel where pollen lands
- BThe stalk that supports the anther
- CThe swollen base of the carpel containing ovules
- DThe male part that produces pollen
38.The diagram shows a seed. Which labelled structure is the food store? (Diagram: icon_scene of a seed with labels)
Medium
- AThe part that provides nutrients to the embryo
- BThe outer protective layer
- CThe embryo plant
- DThe part that develops into a flower
39.A student wants to observe the growth of a pollen tube after pollination. Which of the following is the most suitable method?
Medium
- APlace pollen grains on a glass slide with a sugar solution and observe under a microscope
- BPlace pollen grains on a dry glass slide and observe under a microscope
- CPlace pollen grains on a stigma and observe the whole flower under a microscope
- DPlace pollen grains in water and observe under a microscope
40.A scientist wants to compare the effectiveness of two different pollinators (bee species A and bee species B) on apple fruit set. Which experimental design would give the most reliable results?
Hard
- AUse one apple tree and allow both bee species to visit it, then count the number of fruits
- BUse two separate apple trees, one for each bee species, and ensure all other conditions are the same
- CUse multiple apple trees for each bee species, randomly assign trees to bee species, and control environmental conditions
- DUse one apple tree and first allow bee species A to visit for a week, then bee species B for a week, and compare fruit counts

Revision notes

## Fertilisation and Seed Formation - **Pollination** must occur first: pollen from the **stamen** (male part) reaches the **carpel** (female part). - After pollination, pollen on the stigma germinates and grows a **pollen tube** down the style to the ovary. - The male sex cell nucleus moves through the tube and joins with the ovule nucleus – this joining is **fertilisation**. - The fertilised ovule becomes a **seed**, containing an **embryo plant**, a **food store**, and a **seed coat** for protection. - The ovary develops into a **fruit**, which protects seeds and aids dispersal (e.g., berries, nuts, pods). - Many crops depend on insect pollinators (bees, butterflies, beetles). Without them, yields drop → less food, higher prices, affecting global food security.

Pollination: Transfer of pollen from the stamen (male part) to the carpel (female part) of a flower.
Fertilisation: The joining of the male sex cell nucleus with the ovule nucleus after a pollen tube grows to the ovary.
Pollen tube: A tube that grows from a pollen grain down the style to the ovary, carrying the male sex cell.
Seed: A fertilised ovule containing an embryo plant, a food store, and a seed coat.
Fruit: The developed ovary of a flower that protects seeds and aids in their dispersal.
Stamen: The male part of a flower, consisting of anther and filament.
Carpel: The female part of a flower, consisting of stigma, style, and ovary.

Flashcards

What is fertilisation in plants?

Fertilisation is the process where the nucleus of a male sex cell joins with the nucleus of an ovule.

What must happen before fertilisation?

Pollination must occur first, where pollen from the stamen reaches the carpel.

What happens after a pollen grain lands on a stigma?

It germinates and grows a pollen tube down through the style towards the ovary.

What travels through the pollen tube?

The nucleus of a male sex cell moves through the tube to join with the ovule's nucleus.

What does a fertilised ovule become?

A seed.

What does a seed contain?

An embryo plant, a food store, and a seed coat.

What is the function of the food store in a seed?

To nourish the embryo as it grows.

What is the seed coat?

A protective outer layer of the seed.

What does the ovary become after fertilisation?

A fruit.

What is the function of a fruit?

To protect seeds and aid in their dispersal.

Name three types of fruits.

Berries, nuts, and pods.

What is the male part of a flower called?

The stamen.

What is the female part of a flower called?

The carpel.

What is pollination?

The transfer of pollen from the stamen to the carpel.

Why are insects like bees important for crops?

They pollinate flowers, enabling plants to produce seeds and fruit.

What would happen if insect pollinators declined?

Crop yields would decrease, leading to reduced food availability and higher prices.

How does declining bee populations affect food security?

It reduces the quantity and diversity of foods available, impacting global food security.

What is the pollen tube?

A tube that grows from the pollen grain down the style to the ovary, carrying the male nucleus.

Where does fertilisation occur in a flower?

In the ovule, inside the ovary.

What is the embryo plant?

The young plant inside a seed that will grow into a new plant.

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