Download 9Aa Inherited characteristics/How variation occurs

Starter and plenary suggestions for Exploring Science Unit 9A
Page 1
Unit 9A – Inheritance and selection
9Aa Inherited characteristics/How variation occurs
Starter
This topic and the next develop the idea of characteristics first covered in Units 7A and 7B,
and also look at how variation in characteristics occurs.
Worksheet 9Aa/1 (in Copymaster File 9) provides a card sort activity that can be used to
remind pupils of how fertilisation happens in plants and animals, and should also allow you
to see how much they remember from earlier work.
Worksheet 9Aa/6 (on the website) provides a list of characteristics of humans, and pupils are
asked to classify them into differences that are inherited, caused by the environment, or both.
Some blank lines have been left at the bottom for pupils to add more characteristics if they
can think of any. Give pupils a few minutes to fill in the worksheet, and then hold a class
discussion to ask pupils to explain their answers and to see if everyone agrees with them.
There is more than one possible answer to several of the questions – for instance, hair colour
is inherited, but can also be affected by the environment (getting bleached by the sun in the
summer, or by being dyed), and even eye colour can be changed by wearing coloured contact
lenses.
Instead of the class discussion, you may wish to ask pupils to keep their answers to this
exercise until the end of Topic 9Ab, when they could revisit the list and correct any answers
they got wrong.
Answers:
Colour of eyes: inherited (or both, if coloured contact lenses are considered)
Colour of skin: both (inherited, but also affected by the sun, or by applying artificial tan)
Colour of hair: both (inherited, but can also be dyed)
Length of hair: environmental
Scars: environmental
Height: both (inheritance and nutrition will both play a part)
Weight: both (inheritance and nutrition will both play a part)
Shape of finger nails: both (the basic shape is inherited, but nails can be cut/filed to different
shapes)
Need to wear glasses: both (normally inherited, although accident or illness could sometimes
result in the need to wear glasses)
Shape of nose: inherited (unless plastic surgery is also considered!)
Other things that could be added are curliness of hair, being good at particular sports, tattoos,
body piercings, etc.
Plenary
Worksheet 9Aa/7 provides a set of anagrams for pupils to unscramble, and then write clues
for. Pupils could be given a few minutes to do this and to write their clues, and could then be
asked to read out their clues to see if other members of the class can correctly guess the
word. If pupils need help, they could refer to pages 4 and 5 in the Pupil’s Book, as all the
anagrams are bold words on those pages.
Exploring Science 9
This material may be adapted for use in schools.
© Pearson Education 2003
Starter and plenary suggestions for Exploring Science Unit 9A
Page 2
Answers:
1 characteristics
2 variation
3 inherit
4 DNA
5 nucleus
6 chromosomes
7 genes
8 gametes
9Ab Different varieties/Environmental effect
Starter
Show pupils two or three different varieties of apple, and ask them what the differences are
between the different varieties. Pupils should suggest that the size, shape and colour are
different, and may also suggest that juiciness and taste may also vary. This can lead on to a
discussion of what a variety is, and pupils could also be asked to suggest any other fruits or
vegetables they know of that come in different varieties. The discussion could be extended to
flowers, as pupils may know that different varieties of roses, daffodils, tulips, etc can be
obtained.
If appropriate, you could also ask pupils to suggest why apples within a variety are different
to each other, eliciting various environmental factors that could cause differences in size,
colour, juiciness etc.
Any fruit or vegetable will do as a focus for the discussion, but you may already have apples
available if the class is going to do Practical 2, and different varieties of apples are usually
easy to buy in supermarkets.
Plenary
Give pupils copies of worksheet 9Ab/8 (on the website), and ask them to produce questions
to fit the answers given. Pupils can work in small groups before holding a short class
discussion to decide what the questions should be. This can be done orally or in writing. The
answers/questions cover the content of this and the previous topic.
Possible questions for the answers provided are:
1 What does variation mean?
2 Give two causes of variation.
3 Where is DNA found?
4 What are the sex cells called?
5 How many genes do sex cells have?
6 What is a species?
7 What are varieties?
8 What could some of the differences between pear varieties be?
9 Name some environmental factors that could affect plants.
10 Name some environmental factors that could affect humans.
Exploring Science 9
This material may be adapted for use in schools.
© Pearson Education 2003
Starter and plenary suggestions for Exploring Science Unit 9A
Page 3
Alternatively, Worksheet 9Aa/6 can be used here if it was not used earlier. If it was used in
Topic 9Aa but the answers were not discussed at the time, ask pupils to look at their answers
again (individually or in small groups) and correct any answers that they got wrong before.
9Ac Animal breeding
Starter
Brainstorm pupils’ existing knowledge about breeds of dog, and why they exist. This could
be done as a class discussion, or pupils could be given scrap paper and asked to jot down as
many different breeds of dog as they can, and also different ways that dogs can be used.
Elicit the idea that different breeds of dog are more suited to different purposes, and ask
pupils to suggest how breeds could be improved. This discussion will lead on naturally to the
work on page 8 of the Pupil’s Book.
Plenary
Worksheet 9Ac/1 (in Copymaster File 9) provides a true/false exercise that can be used as a
plenary activity if it is not needed for homework.
Alternatively, Worksheet 9Ac/6 provides a ‘connectives’ exercise to revise the content of
this lesson. Connectives are a set of sentences for pupils to complete in their own words,
including one of the following words: and, because, but, however, such as, therefore, which,
to, so.
Worksheet 9Ac/6 can be given to pupils, or it can be copied onto an OHP slide or written on
the board. Pupils can be given 5 minutes to complete their sentences, and then they can share
their ideas with the class.
The obvious answers to most questions involve using ‘because’ as a connective, but more
able pupils should be encouraged to use the other connectives if they can.
Some possible answers are given below, although these are not the only valid responses:
1
2
3
4
5
Different breeds of dog have different characteristics … because they have been bred for
different purposes / such as being able to run fast or being good at herding other animals /
so they are suitable for different purposes
There are lots of different varieties of sheep … such as mouflon, merino, Wiltshire horn,
etc / which have been bred to give different characteristics that are useful to farmers / and
one variety even eats seaweed!
Selective breeding is useful … because dog breeders or farmers can get the characteristics
they want in their animals / so that sheep can be bred to give good quality wool
Cross-breeding is a type of selective breeding … which can be used to breed animals with
the best characteristics of two different breeds / but uses animals from two different breeds
Animal breeds do not stay useful forever …because the things people want from animals
can change / but breeds that are no longer used are sometimes kept on rare breeds farms
9Ad Plant breeding
Starter
Start the lesson by telling pupils that plants can also be selectively bred for different
characteristics. Use Worksheet 9Ad/2 (in Copymaster File 9) to help pupils to consider the
Exploring Science 9
This material may be adapted for use in schools.
© Pearson Education 2003
Starter and plenary suggestions for Exploring Science Unit 9A
Page 4
characteristics that can be selectively bred, and which characteristics would be useful to
farmers, shopkeepers and consumers.
Plenary
Worksheet 9Ad/4 (in Copymaster File 9) could be used as a plenary activity, with small
groups working on it and then sharing their answers with the rest of the class.
Alternatively, Worksheet 9Ad/7 (on the website) provides a set of cards for a question loop
activity that can be used to summarise the whole Unit, and act as a starting point for revision.
There are 30 cards provided. All cards must be used to close the ‘loop’ – if you do not have
30 pupils in the class, give some pupils more than one card. Alternatively, copy two sets of
cards so that each pupil has at least two cards – two hands should then go up in answer to
every question, and pupils are less likely to mentally switch off when they have used their
card.
Answers:
What are characteristics?
What is variation?
What are inherited characteristics?
Name two inherited characteristics in
humans.
What is DNA?
What is a gene?
Which part of the cell contains genes?
What is the proper name for sex cells?
How many genes do gametes have?
What is a species?
The things that describe what you look
like.
Differences in characteristics.
Characteristics we get from our parents.
Hair colour and eye colour.
Molecules that carry genetic information.
A section of DNA.
The nucleus.
Gametes.
Half the normal number.
A group of similar organisms that can
produce offspring.
What are varieties?
Groups of plants of the same species, but
with clear differences.
What is disease resistance?
When a variety is less likely to catch a
certain disease.
What characteristics may vary between
Size and colour of flowers, thorns, low
different varieties of rose?
growing or climbing.
What are the surroundings of an organism Its environment.
called?
Name some environmental factors of
The amount of light, heat, water, mineral
plants.
salts.
Name some environmental factors of
Diet, diseases, fashion.
humans.
What is a breed?
A set of animals of the same species
which all share some characteristics.
How were greyhounds selectively bred?
By breeding the fastest dogs in each
generation.
Give three different reasons that sheep
Good wool, good meat, survive well in
could be selectively bred.
hilly areas.
What does yield mean?
The amount of meat or milk a breed of
animal produces.
Exploring Science 9
This material may be adapted for use in schools.
© Pearson Education 2003
Starter and plenary suggestions for Exploring Science Unit 9A
What is cross-breeding?
Why is cross-breeding useful?
Why are some chickens bred to survive
well out of doors?
What are the male gametes called in
plants?
Where are the pollen grains produced?
What is pollination?
What happens to the pollen after it lands
on a stigma?
What happens to a fertilised plant egg
cell?
What characteristics might tomatoes be
bred for?
Why might a plant breeder cover a flower
in a plastic bag?
Exploring Science 9
This material may be adapted for use in schools.
Page 5
When animals from two different breeds
are mated.
Farmers can get animals with the best
characteristics of two different breeds.
Because many people want to buy freerange eggs or meat.
Pollen.
On the anthers.
The transfer of pollen from one plant to
the stigma of another.
A pollen tube grows down to the ovary.
It turns into a seed.
Size, taste, quick ripening.
To stop pollen from other flowers landing
on its stigma.
© Pearson Education 2003