Unit
Title:
INHERITANCE AND SELECTION
Caretaker: JES
Unit
No
9A
Lesson Title: INHERITED CHARACTERISTICS
NC
Ref:
Objectives:
(key words are in
bold)
MK - Offspring
are similar to parents but not identical they show variation (plants and animals),
examples of , and that some are inherited. That the nucleus contains genetic info. and fertilisation allows this to be
passed on .
SK - fusion
of male and female gametes produces genetically identical individuals,
that nuclei fuse during fertilisation. That genes carry the genetic
information as DNA which controls inherited characteristics.
CK - about
multiple birth and how identical, non-identical and conjoined twins
are formed. Why brothers and sisters are similar but not identical.
About dominant genes and the human genome project.
Lesson outline: Horsforth Commentary
:Discuss variation, know about genetic info. and that fertilisation is required for the inheritance of certain characteristics.
Use slides as required from Boardworks
Starter activities:
If you were very organised you would have remembered to set a homework that involved bringing in family photos of a couple of generations. These could be used in the following discussion to illustrate the points you are making. Alternatively, why not bring in your family photo album!
Ask pupils to list characteristics of their class mates (may need to start them off with one or two ideas). List them on the board. Ask them why they think we (and other species) are all different (show variation) and which characteristics they think are inherited from parents. Ask them how they think characteristics are inherited from parents, they will probably suggest genes - ask them what a gene is, what it is made of.
Discuss other reasons for variation (the environment) and discuss the fact that these characteristics are not inherited - identify these characteristics from the list on the board.
Main course:
Pupils should know that to pass on genes fertilisation must occur. W/S 9Aa 2 (lower ability) and 9Aa3 are ideal to cover this. make sure they know the word gamete and that it has half the amount of DNA to a normal cell.
DNA extraction:
Method:
Dissolve 3g salt in 100 cm3 water. Add 10 cm3 cheap washing up liquid. Mash up fruit (kiwi works well) and add previous mixture. Leave in 40 o water bath for 15 mins. Filter some into a boiling tube (about 1/3 full). Tilt the tube and slowly add cold ethanol down the side of the tube. The DNA appears as very fine white strands which collect at the interface of the two liquids and that rise as the tiny bubbles do.
Plenary:
Pupils draw a person and
label the characteristics that are inherited and those that are due to
the environment.
Timings:
10-15
40
5
Homework Suggestion:
W/S: 9Aa/4 or 5 for the more able.
or find the definitions of key words such as characteristic, variation, nucleus, inherited, gamete,, gene .....
or research how the different kinds of twins are produced.
Resources:
For DNA extraction:
Salt, water, cheap washing up liquid, kiwi / other fruit 40 o water bath filter funnels and paper, boiling tubes, cold ethanol. Balance.
No naked flames when
using ethanol.
Unit
Title:
INHERITANCE AND SELECTION
Caretaker: JES
Unit
No
9A
Lesson Title: DIFFERENT VARIETIES
NC Ref:
Objectives:
(key words are in
bold)
MK - what
a variety is, that some characteristics are desirable, that
differences are not always visible - such as disease resistance and
flavour. That the environment (environmental factors
such as light) can cause variation.
SK - what
a species is, be able to suggest differences between varieties
and be able to tell there is greater variation between varieties than
within varieties, what disease resistance is.
CK - about
genetic diseases and disorders, that different versions
of the same gene are called alleles, about recessive and
dominant alleles, what phenotype and genotype
mean, about physiotherapy, pancreas, cystic fibrosis,
Huntington's disease.
Lesson outline: Horsforth Commentary
:Pupils investigate different varieties and see that there is variation within the variety but more variation between varieties.
Starter
activity:
Show potatoes of the same variety and discuss the reason for their different sizes (environment). Discuss why different sizes vegetables are rare in supermarkets (they sort them so they look nice).
Show a different variety of potato, discuss the differences between varieties and discuss the reasons for the differences (genetic). Introduce the word species and discuss (write down a definition of species), compare with breeds of dog - varieties of plants and breeds of animals belong to the same species - they are able to breed and produce offspring that themselves can breed. Talk about cross-breeds of dogs as an example (animals are dealt with next lesson).
Main course:
W/S 9Ab/3 or 9Ab/4 (laptops needed). or you could get the pupils to collect their own data from two varieties of apple.
If you do this, split the class into small groups. Give each group 5 of each of 2 varieties of apple, they weigh them, record the results and present as a bar chart.
They must then write a conclusion.
They should aim to show the characteristics vary more between varieties than it does within a variety.
They should conclude that one variety has a greater mass than the other and also that there is a fair amount of variation within a variety.
Plenary:
W/S 9Ab/5
Timings:
10
40
10
Homework Suggestion:
For the more able: 9Ab/6 or 9Ab/7
or W/S
9Ab/5
Resources:
Two varieties of potato - obviously different.
Two varieties of apple -
obviously different sizes, like cox's and cooking apples.
Unit
Title:
INHERITANCE AND SELECTION
Caretaker: JES
Unit
No
Lesson Title: ANIMAL BREEDING
NC Ref:
Objectives:
(key words are in
bold)
MK - the
definition of a breed, how some charateristics in animals are
desirable for farmers.
SK - know
about selective breeding - that farmers select animals with
special characteristics to produce offspring and that this results in
the production of new breeds of animal. Animals may be cross-bred.
What yield means.
CK - why
rare breeds are kept and about the origin of modern breeds.
Lesson outline: Horsforth Commentary
:Pupils learn how selective breeding is carried out and about the sorts of characteristics animals are bred for.
Starter
activity:
W/S
9Ac/1
Main course:
Remind pupils what a breed is, i.e a variety but usually applied to animals. Discuss how dogs are bred selectively for certain purposes, could show a selection of pictures of dog breeds.
Pupils describe in their own words how to selectively breed - i.e
-
choose animals or plants with desired characteristic
-
breed them
-
choose the offspring that also show the desired characteristic
-
breed them
-
repeat for several generations
Discuss farming and how they need to produce more food (and make money) than ever. Discuss the desirable characteristics of dairy cows, pigs, beef cattle, sheep and poultry. Could do 9Ac/2.
Discuss cross-breeding in the context of dogs. Look at the pictures of the dogs on page 8/9 in the text book.
Answer the questions on page 8/9 in the text book, point out the last paragraph that explains why rare breeds should be preserved.
Pupils could research the ethical dilemmas associated with selective breeding such as the health problems in certain breeds of dog, breeding for a purpose (for food) vs. for our entertainment (in show breeds, grey hounds etc) and write about them.
Plenary:
Show pupils a picture of a Shire horse. They must :
a) say what it was used for
b) list its desirable characteristics
c) describe how it was bred to look like it does
Timings:
10
40
10
Homework Suggestion:
Continue / start research
and write report.
Resources:
Exploring Science 9 books
Pictures of different dog
breeds and a Shire horse.
Unit
Title:
INHERITANCE AND SELECTION
Caretaker: JES
Unit
No
9A
Lesson Title: PLANT BREEDING
NC Ref:
Objectives:
MK - Plant
breeders select healthy plants with particular characteristics to
breed from, some visible and some invisible. Fertilisation in plants
requires a pollen grain and an egg cell (two sex cells) and is similar
to fertilisation in animals.
SK - how
selective pollination is done and the apparatus needed, that
pollination is the transfer of pollen from anther to
stigma, that fertilisation of the nucleus of an egg cell inside
an ovule by the nucleus of a pollen grain cell produces a new
individual.
CK - there
are problems with selective pollination which must be overcome, i.e.
ensuring that a flower is pollinated by the selected pollen only,
about dominant and recessive genes in plants, about Mendel's work with
pea plants, how to work out the genotype and phenotype of crosses.
Lesson outline: Horsforth Commentary
:Pupils learn how and why plants are selectively bred.
Starter
activity:
List the visible features that plant breeders would select for (like size, colour, texture, shape, smell etc.) and say why they would want each of them. Pupils describe how this would be done - recapping selective breeding previously discussed with animals.
Show a big, nice looking carrot and a small weedy looking one. Ask which one they would prefer to buy - demonstrates why the breeder would choose the big carrot plant to breed from.
Main course:
W/S 9 Aa/1 is a cut and stick to show the differences between fertilisation in plants and animals.
Pollen grain practical - (shows how small pollen really is). Remove pollen grains from anthers of plants with a paint brush or mounted needle. Place in a drop of water on a slide, methylene blue may be a useful stain, lower a coverslip onto it.
Ask the class how they could go about breeding plants and the equipment they might need. Look at the pictures on page 11. Could use 9Ad/5, pupils should evaluate each others responses to question 2.
Discuss cloning and how it may be done easily with plants. Set up a cutting from a geranium or African violet. Cut from near the stem and place in a test-tube of water or plant in potting compost. This demonstrates asexual reproduction and the production of a clone - genetically identical organism.
Plenary:
Show the class some frozen peas and some fresh peas. Pupils should write a list of the characteristics that we could investigate to show how selective breeding has produced peas with different characteristics.
Timings:
10
40
10
Homework Suggestion:
Resources:
Big carrot and a weedy carrot, scissors and glue, slides, coverslips, paint brushes, methylene blue, microscopes and video microscope. Exploring Science 9. Geranium or African violet, compost.