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Fertilisation

In this worksheet students are able to review their understanding of the different types of fertilisation, what happens during fertilisation and what results from it.

'Fertilisation' worksheet

Key stage:  KS 3

Curriculum topic:  Biology: Structure and Function of Living Organisms

Curriculum subtopic:  Reproduction

Difficulty level:  

down

Worksheet Overview

QUESTION 1 of 10

Fertilisation is the joining of special sex cells called GAMETES, so if you want to know more of what that's about, you've come to the right place!

 

 

 

In this worksheet you can take time to explore what fertilisation is all about, where and how it happens and then what happens after fertilisation has taken place.

 

Let's see how you get on....

GAMETES is the name given to those special sex cells used by most organisms to carry their genetic information (the stuff that's inherited) on to the next generation.

 

See if you can sort out which gamete is which in this table. Place the gametes...

  • sperm
  • pollen
  • ovule
  • egg

 

...into the correct boxes according to whether they are used by animals or plants and which ones are produced by male or female. (Write your answers in lower case).

 PlantAnimal
Male gamete
Female gamete

Some organisms bring their gametes together inside the organism (which is called INTERNAL FERTILISATION), while others simply allow their gametes to mix outside the organism, generally in water (called EXTERNAL FERTILISATION).

 

Below is a list of animals - your job is to sort out which animals in the list use which type of fertilisation by dragging INTERNAL or EXTERNAL next to the animal.

Column A

Column B

frog
EXTERNAL
tuna fish
INTERNAL
crab
INTERNAL
seagull
INTERNAL
grass snake
EXTERNAL
mouse
EXTERNAL
jellyfish
EXTERNAL
snail
INTERNAL
sperm whale
EXTERNAL
starfish
INTERNAL

External fertilisation results in young that have to fend for themselves from day one.

 

Tick TWO reasons in this list that you think gives organisms using external fertilisation an advantage:

Many eggs can be fertilised at one time.

The young are independent as soon as they hatch out.

Large amounts of eggs and sperm are released.

The organisms don't have to come into contact with each other.

The fertilised eggs don't have to be protected.

Many organisms use internal fertilisation, including all mammals.

 

Tick TWO reasons that you think gives animals using internal fertilisation an advantage over those that don't.

fewer eggs and sperm are needed

animals have to be in contact to mate

smaller numbers of young are produced

there is a greater chance of the fertilised egg developing into an adult

Not all animals that use internal fertilisation continue on to develop the young within their bodies. Most then produce eggs from which the young hatch out.

 

Pick out the animal from this group which keeps the fertilised egg inside its body, where it develops until it is ready to be born.

dolphin

trout

butterfly

pigeon

turtle

Look carefully at this description of an animal group:

 

"These animals use internal fertilisation, the sperm and egg meeting inside the female, and the fertilised egg remains inside the female, developing safely inside her until it is at an advanced stage before it is born. After birth the parent animals care for the young, feeding it with milk and teaching it to fend for itself."

 

Which animal group is being described?

insects

mammals

reptiles

fish

birds

In humans specialised gametes are produced called sperms and eggs. These cells are specially designed for their job.

 

Look at each description below and decide whether it applies to the sperm or the egg by dragging SPERM or EGG next to each one. (If you can't see all the words in the boxes on the left, hover your mouse over them).

Column A

Column B

has a tail
SPERM
smallest human cell
SPERM
largest human cell
EGG
can swim
EGG
contains large food reserves
SPERM

When the sperm and egg join, at fertilisation, the genes they are carrying are combined into a brand new set in the ZYGOTE (or first cell) of the new individual. Whereabouts in the sperm and egg are the genes found?

cytoplasm

chloroplast

nucleus

In humans all our characteristics are held on genes - that is our genetic information. What proportion of these genes are passed into each the sperm and egg in order to form the gene set of the new individual?

100%

50%

25%

  • Question 1

GAMETES is the name given to those special sex cells used by most organisms to carry their genetic information (the stuff that's inherited) on to the next generation.

 

See if you can sort out which gamete is which in this table. Place the gametes...

  • sperm
  • pollen
  • ovule
  • egg

 

...into the correct boxes according to whether they are used by animals or plants and which ones are produced by male or female. (Write your answers in lower case).

CORRECT ANSWER
 PlantAnimal
Male gamete
Female gamete
EDDIE SAYS
Sperm and egg are the ones you are familiar with and they are used by most animals who reproduce in this way. The gametes used by flowering plants are pollen and ovule: the pollen is carried by wind, insect, etc. and grows a tube down into the ovary of the flower to join with the ovule.
  • Question 2

Some organisms bring their gametes together inside the organism (which is called INTERNAL FERTILISATION), while others simply allow their gametes to mix outside the organism, generally in water (called EXTERNAL FERTILISATION).

 

Below is a list of animals - your job is to sort out which animals in the list use which type of fertilisation by dragging INTERNAL or EXTERNAL next to the animal.

CORRECT ANSWER

Column A

Column B

frog
EXTERNAL
tuna fish
EXTERNAL
crab
EXTERNAL
seagull
INTERNAL
grass snake
INTERNAL
mouse
INTERNAL
jellyfish
EXTERNAL
snail
INTERNAL
sperm whale
INTERNAL
starfish
EXTERNAL
EDDIE SAYS
There may have been some surprises there - and bet you thought "I don't know how that animal reproduces!". Actually, it's easier than you thought: most animals that live in water (including the sea) will release their gametes into the water where they mix; so that's frog, tuna fish, crab, jellyfish, starfish. The only exception in the list is the sperm whale which is a mammal and so uses internal fertilisation (like all mammals). The others all use internal fertilisation, including snails!
  • Question 3

External fertilisation results in young that have to fend for themselves from day one.

 

Tick TWO reasons in this list that you think gives organisms using external fertilisation an advantage:

CORRECT ANSWER
Many eggs can be fertilised at one time.
The organisms don't have to come into contact with each other.
EDDIE SAYS
The key word in the question is ADVANTAGE: is it an advantage for hatchlings to be independent (no, they get eaten easily), for loads of eggs and sperm to be used (no, much is wasted) and for the fertile eggs not to be protected (no, they get eaten)? On the other hand, not coming into direct contact can be a real advantage (for example - look at certain male spiders, whose mates eat them!) and many eggs can be fertilised (a frog releases about 2000 eggs, but only about 2-3 will make it all the way to adult frogs).
  • Question 4

Many organisms use internal fertilisation, including all mammals.

 

Tick TWO reasons that you think gives animals using internal fertilisation an advantage over those that don't.

CORRECT ANSWER
fewer eggs and sperm are needed
there is a greater chance of the fertilised egg developing into an adult
EDDIE SAYS
It is an advantage not to waste resources in making masses and masses of eggs and sperm and also in the fact that many of those fertilised eggs will have a greater chance of making it to adulthood; mind you, that also depends on the level of parental care. Producing fewer offspring is not an advantage, unless they are cared for, and being in contact can be a problem: male praying mantises are often eaten by the female and mating animals are more vulnerable to predation.
  • Question 5

Not all animals that use internal fertilisation continue on to develop the young within their bodies. Most then produce eggs from which the young hatch out.

 

Pick out the animal from this group which keeps the fertilised egg inside its body, where it develops until it is ready to be born.

CORRECT ANSWER
dolphin
EDDIE SAYS
Yes, the dolphin is a sea-living mammal, so the young dolphins are born straight into the water. All the others produce fertilised eggs, only the pigeon nurtures those eggs and chicks to give them a reasonable chance of making it to adulthood.
  • Question 6

Look carefully at this description of an animal group:

 

"These animals use internal fertilisation, the sperm and egg meeting inside the female, and the fertilised egg remains inside the female, developing safely inside her until it is at an advanced stage before it is born. After birth the parent animals care for the young, feeding it with milk and teaching it to fend for itself."

 

Which animal group is being described?

CORRECT ANSWER
mammals
EDDIE SAYS
The key clue in the description is "feeding it with milk"; only mammals do that. Other parts of the description could fit a variety of the other groups, but only mammals fulfil ALL the requirements.
  • Question 7

In humans specialised gametes are produced called sperms and eggs. These cells are specially designed for their job.

 

Look at each description below and decide whether it applies to the sperm or the egg by dragging SPERM or EGG next to each one. (If you can't see all the words in the boxes on the left, hover your mouse over them).

CORRECT ANSWER

Column A

Column B

has a tail
SPERM
smallest human cell
SPERM
largest human cell
EGG
can swim
SPERM
contains large food reserves
EGG
EDDIE SAYS
Sperms are amazing swimmers, lashing their tails to and fro to beat a path towards the egg. At 2.5 micrometres in size sperm are our smallest cells, aiming to fertilize our largest cell - the egg - at 100 micrometres across. One of the reasons it's so big is because it contains the foodstores to sustain the developing egg on its way to the uterus.
  • Question 8

When the sperm and egg join, at fertilisation, the genes they are carrying are combined into a brand new set in the ZYGOTE (or first cell) of the new individual. Whereabouts in the sperm and egg are the genes found?

CORRECT ANSWER
nucleus
EDDIE SAYS
The nucleus is known as the 'control centre' of the cell - well that's because it contains the instructions on 'how to work' on the genes that make up the nucleus. Makes sense, once you think about it!
  • Question 9

In humans all our characteristics are held on genes - that is our genetic information. What proportion of these genes are passed into each the sperm and egg in order to form the gene set of the new individual?

CORRECT ANSWER
50%
EDDIE SAYS
The father and mother contribute half a set of genes each, so that the baby gains a full set, a combination of the mother's and father's genes.
---- OR ----

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