Year 8 Science Distance Learning

BookletGenes

Name: ……………………………………….

Science Teacher: …………………………….

Lesson 1: Natural SelectionLearning objective: To be able to explain how species evolve over time

https://www.bbc.co.uk/bitesize/topics/zpffr82/articles/z7hj2nb

Learning outcomes:● I will be able to describe the theory of natural selection● I will be able to explain why species evolve over time

Starter: Take 5 minutes to form a spider diagram of everything that you know about evolution, how animals and plants are adapted to their environment and fossils.

What do I know about evolution?

Recap from Year 7

1. What are the two causes of variation?

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2. Continuous variation is shown by any characteristic (feature) that can take any

value e.g. weight. Give another example of a characteristic that shows continuous

variation.

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3. Discontinuous variation is shown by characteristics that can only occur in certain

categories e.g. gender. Give another example of a characteristic that shows

discontinuous variation.

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How do organisms evolve?Organisms evolve through the process of natural selection. They change slowly to becomebetter adapted to their environment. This takes many years, sometimes millions, as ithappens over a number of generations.

Natural selection

1) Organisms in a species show variation – this is caused by differences in their genes

2) The organisms with the characteristics that are best adapted to the environment survive and

reproduce. Less well adapted organisms die. This is ‘survival of the fittest’.

3) Genes from successful organisms are passed on to their offspring.

4) This process is repeatedmany times. This can lead to the development of a new species.

What is evolution?

Scientists believe that the species we see on Earth today have gradually developed overmillions of years.. This is called the theory of evolution.

Evolution started with uni-cellular organisms. These organisms, similar to bacteria, livedin water more than three billion years ago. Over time they have evolved to becomemulti-cellular organisms.

Fossils provide most of the evidence for evolution. Fossils are the remains or traces, ofplants or animals that lived many years ago. The fossil record provides evidence ofspecies that no longer exist.

Questions

1. What is a uni-cellular organism? (line 3)

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2. What is a multi-cellular organism? (line 5)

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Evolution

1. 2.

3. 4.

Produce a cartoon strip showing the evolution of an organism of your choice. This could be a real organism or a made-up one

Lesson 2: Who was Charles Darwin?Learning objective: To be able to explain why Charles Darwin was one of the most famous

scientists of all time

Learning outcomes:● I will be able to state the theory that Darwin was famous for● I will be able to describe the main points of Darwin’s theory

● I will be able to state the evidence that Darwin’s theory is based on

Carry out internet research to find the answers to the following questions:

1) When was Darwin born? _________________

2) What group of islands is he well known for visiting? ____________________________

3) Name the ship he was on when visiting these islands?__________________________

4)What type of birds did he study whilst visiting these islands? ___________________

5) Describe what features of these birds that Darwin studied. What conclusion did he arrive

at after studying these features? ____________________________________________

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6) Describe two pieces of evidence in support of Darwin’s theory of Natural Selection

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7) What is the name of the very famous book that Darwin wrote

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8) Why was this book very controversial? (Why did people disagree and angered by its

contents)

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9) When was Darwin’s book finally published? ________________________________

Another scientist, Alfred Wallace, was working on his own theory of natural selection andevolution. Wallace and Darwin read each others unpublished work. This is an example ofpeer review, where a scientist’s work is checked by another scientist who works in a similararea of science. Darwin’s and Wallace’s ideas were so similar that they jointly published thetheory of evolution in a scientific paper.

Watch the BBC Bitesize cliphttps://www.bbc.co.uk/bitesize/topics/zpffr82/articles/zkv26yc

Lesson 3 Extinction Learning objective: To be able to describe why a species becomes extinct

https://www.bbc.co.uk/bitesize/guides/zw9jq6f/revision/2

Learning outcomes:● I will be able to state some factors that lead to the extinction of a species

● I will be able to describe what biodiversity is and why it is important

What does extinction mean?If a species is not adapted to its environment, it will not survive. Organisms will die before reproducing and eventually by this process of natural selection, the species will become extinct. A species becomes extinct when there are no more individuals of that species left anywhere in the world.

How do we know other species existed?The fossil record shows us that many species have become extinct. The ammonite fossil in the picture below is from the Jurassic period and is 160 million years old.

therockgallery/jurassic-ammonite

Can you name two organisms that have become extinct?

1) _______________________________

2) _______________________________

How do organisms become extinct?

● changes to the organisms environment

● destruction of habitat

● outbreak of a new disease

● new predator

● Increased competition for resources (organisms battling for the same things)

Draw a picture of the causes of extinction in each of the boxes below to help you remember them

How do organisms become extinct? Changes to the organism’s

environment

Destruction of habitat Outbreak of a new disease

Introduction of a new predator Increased competition for resources

Biodiversity is a measure of the variety of all the different species of organisms on Earth. When a species becomes extinct, biodiversity is reduced.

Biodiversity is vital for maintaining populations. The greater the variation within a species the more likely some members of the population will survive environmental changes. This reduces the likelihood of that species becoming extinct.

The Dodo was a large, flightless bird that lived on the island of Mauritius. It is now extinct. Carry out research to find out why scientists think this was

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A species becomes ___________________ when there are no more individuals of that

species left ______________ in the world.

Changes in a species _________________ or the introduction of new

____________________ can cause a species to become extinct.

Plenary:Return to your original spider diagram and add new knowledge to this in a different coloured pen.

Lesson 4: Preserving biodiversityLearning objective: To learn how preserving biodiversity benefits humans

https://www.bbc.co.uk/bitesize/guides/zw9jq6f/revision/3

Learning outcomes:● I will be able to describe what is meant by an endangered species● I will be able to describe some techniques used to prevent extinction● I will be able to describe how preserving biodiversity benefits humans

Can we prevent extinction?

Species that are at risk of extinction are called endangered species. This means that there

are very few of the species left. An example is the giant panda. Their numbers have been

reduced by loss of habitat and by being killed by poachers.

Read the ‘Project Tiger’ information and then answer the questions that follow

1. State the difference between an endangered species and one that is extinct. Use examples where possible.

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2. Between 1900 and 1979, the tiger population fell by about 97%. This means that tigers are now classed as an endangered species. Describe three reasons for this dramatic decline.

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3. Suggest a reason why population figures for tigers are only estimates.

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What is conservation?Conservations means protecting a natural environment, to ensure that habitats are not lost. Protecting an organisms habitat increases their chance of survival, allowing them to reproduce.

Conservation also:- Reduces disruption to food chains and food webs- Makes it possible for medicinal plant species to be discovered

The UK has over 4000 conservation areas where habitats are protected. These are known as Sites of Special Scientific Interest (SSSI).

What is captive breeding?Captive breeding means breeding animals in human-controlled environments. The aim of captive breeding is to:- Create a stable, healthy population of a species- Gradually re-introduce the species back into its natural habitat

ExtensionCan you think of any problems associated with captive breeding?

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What are gene banks?Gene banks store genetic samples from different species. In the future they can be used for research, or to produce new individuals. There are a number of different types of gene bank. These include:

- Seed banks – dried seeds of plants are stored at low temperatures- Tissue banks - buds and other cells from plants are stored- Cryobanks – a seed or embryo is preserved at very low temperatures, normally in

liquid nitrogen; sperm and egg cells from animals can also be stored in this way

Watch the video clips:https://www.kew.org/science/collections-and-resources/collections/seed-collection

https://www.youtube.com/watch?v=GK_vRtHJZu4

Lesson 5: InheritanceLearning objective: To learn how characteristics are inheritedhttps://www.bbc.co.uk/bitesize/guides/zp7thyc/revision/2

Learning outcomes:● I will be able to describe how characteristics are inherited

● I will be able to describe the relationship between DNA, genes and chromosomes● I will be able to explain how DNA mutation may affect an organism and its offspring

You inherit characteristic (features) from your parents through genetic material stored inthe nucleus of your cells. This material is a chemical called DNA (deoxyribonucleic acid).DNA contains all the information needed to make an organism.

ChromosomesInside the nucleus, your DNA is arranged into long strandscalled chromosomes. Different species have differentnumbers of chromosomes in their nucleus. Humans have46 chromosomes; whereas cats have 38 chromosomes.

GenesEach chromosome is divided into sections of DNA. Thesections hold the information to produce characteristicsand are called genes Each chromosome containsthousands of genes.

Task: Arrange the following in order of size, starting with the smallest

cell chromosome gene DNA nucleus

__________________ (smallest)

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__________________

__________________

__________________ (largest)

How is genetic material inherited?

Inside the nucleus of you cells, the 46 chromosomes are arranged into 23 pairs. One copy of the chromosome of each pair comes from your mother and the other comes from your father.

Egg and sperm (gametes) are the only cells to contain 23 chromosomes. They only have one copy of each chromosome. During fertilisation, the egg and sperm cells join together. When the nuclei join, their chromosomes pair up, producing an embryo with 46 chromosomes.

Answer the following:

What happens when DNA becomes damaged?When DNA is copied to make new cells it can become damaged. This change in DNA is known as a mutation. If a change happens in a gene it can affect that organism’s characteristics. If a mutation happens in a gamete cell (egg or sperm), then this altered form of DNA may be passed onto the organisms’ offspring.

True or

False?

Genes are made of DNA and code for characteristics

Many genes make a chromosome

Many chromosomes are found outside the nucleus

The nucleus is in the membrane of the cell

An organisms characteristics are controlled by its genes

When an organism reproduces it passes on its nucleus to the next

generation

The cell is the basic building block of all organisms

Identify these structures in the diagram below: cell, nucleus, chromosome, gene, DNA.You will need to use some of the terms more than once.

Lesson 6: DNALearning objective: To learn about the structure of DNA

https://www.bbc.co.uk/bitesize/topics/zpffr82/articles/zvwbcj6

Learning outcomes:● I will be able to describe the structure of DNA

● I will be able to describe how scientists worked together to discover the structure of DNA

DNA has three main features:

1) It is made up of two strands

2) The strands are joined together by four different chemicals called bases: A, T, G and C.

3) The strands are twisted together to form a double-helix shape

Fantastic factDid you know you share 97% of your DNA with a gorilla and 50% with a banana!!!

Many scientists worked together to discover the structure and function of DNA. Although we have a lot of information about DNA, research is still continuing. It is hoped that this will lead to the prevention and cure of many diseases in the future.

Do you know the only individuals who have identical DNA? _____________________

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Read the information sheets about the work of the scientists (on this page and the next).Use the grid to record the information into how each team of scientists contributed to

the discovery of DNA.

Team 1: Rosalind Franklin and Maurice Wilkins Team 2: James Watson and Francis Crick

Lesson 7 : GeneticsLearning objective: To learn why offspring are not identical to their parents

https://www.bbc.co.uk/bitesize/guides/zcdfmsg/video

Learning outcomes:● I will be able to describe the difference between dominant and recessive alleles

● I will be able to use a Punnett square to show how genes are inherited● I will be able to explain why offspring are not identical to their parents

Which characteristics will you inherit?For each characteristic, like blood group or eye colour, you have two genes. One gene isinherited from your mother and one from your father. These two genes may be the same,or different. Different forms of the same gene are called alleles.

Some alleles will always produce a characteristic in an organism. These are calleddominant alleles. You only need to inherit one copy of a dominant allele for thecharacteristic to appear (expressed) in the organism. The other form of alleles arerecessive alleles. You need to inherit two copies of a recessive allele to inherit thatcharacteristic e.g. the allele for blue eyes is recessive, so you will only have blue eyes if youinherit the blue allele from both your mother and your father i.e. two copies.

To have blue eyes you

need to have two copies

of the allele for blue eyes

Complete the following:

Different forms of the same gene are known as ______________ .

________________ alleles will always be expressed if they are present.

_____________ alleles will only be expressed if two copies are present.

When a sperm fertilises an egg, genes from the mother join with genes from the father.

This results in a combination of alleles present in the offspring.

Can characteristics be predicted?

A ‘genetic cross’ can predict what an organism’s offspring will look like. The alleles are

represented by letters with a capital letter given to the dominant allele and the recessive

allele given the same letter but the lower case version.

For example, B is used to represent brown eyes which is dominant and b is used for blue

eyes, which is recessive.

A diagram called a Punnett square shows the possible combinations of alleles in a genetic

cross e.g. when a blue-eyed mother (bb) is crossed with a brown-eyed father (BB).

All Bb and because B, brown eyes is dominant, offspring can only have brown eyes i.e.

100% brown-eyed offspring.

B B

b Bb Bb

b Bb Bb

Father (Brown-eyed)

Mother

(blue-eyed)

Possible allele

combinations of

offspring

B b

B

b

1)

A Brown-eyed father (Bb) is crossed with a blue-eyed mother (bb).

What possible eye colours could the offspring have?

Fill in the Punnett square below to show the possible combinations of alleles

What is the chance of having a brown-eyed child? ______________

What is the chance of having a blue-eyed child? ________________

2)

A Brown-eyed father (Bb) is crossed with a Brown-eyed mother (Bb). However each

parent carries a copy of the blue-eyed allele.

What possible eye colours could the offspring have?

What is the chance of having a brown-eyed child? ______________

What is the chance of having a blue-eyed child? ________________

B b

B

b

Offspring produced from two parents inherit alleles from both parents. They therefore

inherit a unique combination of alleles that is different from their parents. This is why

offspring are not identical to their parents,

Lesson 8 : Genetic modificationLearning objective: To learn what is meant by genetic modification

https://www.youtube.com/watch?v=rx953M-tpp4

Learning outcomes:● I will be able to describe how a product is produced using genetic modification

● I will be able to describe some advantages of genetic modification

What is genetic modification?Scientists are able to alter an organism’s genes to produce an organism with desiredcharacteristics. For example, crops can be produced that are resistant to disease. This iscalled genetic modification.

Examples of genetic modificationMany organisms have been genetically modified. For example:● cotton – to produce high yields● corn – to produce toxins (poison) that kill insects● bacteria – to produce medicinal drugs

How can you alter an organism’s genes?To create a organism with desired characteristics, scientists take genes from anotherorganism that show the characteristic. These are know as foreign genes. The foreigngenes are put into plant or animal cells at a very early stage of the organism’sdevelopment.Bacteria can be genetically modified to produce useful chemicals e.g. vaccines andantibiotics.

Carry out internet research to find two disadvantages or concerns about the geneticmodification of organism’s.

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Complete the following:

Scientists can insert ________________ genes into organisms to produce desired

__________________________ . This is called ________________ modification. For

example, bacteria can be modified to produce ________________________ .

Plenary: Use the grid below to recall five facts from each of the lessons in the topic, you can use images to help with this if you feel it is beneficial, but these would need to be clearly annotated (labelled).

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