Download Topic CB3 Genetics Revision sheet

Topic CB3 Genetics – Revision
Task 1. Can you name the units below used to measure growth.
m = …………………………………………………
g = …………………………………………… Km = ……………………………………
l = …………………………………………… mg = ………………………………………….. µm = …………………………………………
ml = …………………………………………. Kg …………………………………………
Task 2: Decide what kind of variation the following are and link to the correct variation, one
has been done for you:
Leaf size
Height (of animal or plant)
Genetic /
discontinuous
variation
Leaf colour
Environmental
Eye colour
/ continuous
Blood group
variation
Skin colour
Mass (weight)
Task 3. Answer the questions:
1. What do we need meiosis for? ……………………………………………………………………
2. Name a haploid cell and a diploid cell. …………………………………………………………
3. Explain why gametes need to be haploid? …………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………
4. Define the following words:
Allele: . ……………………………………………………………………………………………………………………………
Gene: ……………………………………………………………………………………………………………………………
Heterozygous: ……………………………………………………………………………………………………………………………
Homozygous: ……………………………………………………………………………………………………………………………
Genotype: ……………………………………………………………………………………………………………………………
Phenotype: ……………………………………………………………………………………………………………………………
Genome: ……………………………………………………………………………………………………………………………
Mutation: ……………………………………………………………………………………………………………………………
Task 4: Put these sentences in the correct order to give the process of meiosis. Give
the correct order here ……………………………………………………
1.
2.
3.
4.
5.
6.
Metaphase 1: chromosomes line up in pairs in the middle of the cell.
Telophase 1 and cytokinesis 1: Cell splits into two.
Interphase: chromosomes replicate
Anaphase 1: Chromosome pairs move away from each other.
Prophase 1: nucleus disappears
The 2 cells then splits again – producing 4 haploid daughter cells.
Task 5: Can you compare meiosis with mitosis? Give three differences between meiosis
and mitosis.
Mitosis
Meiosis
1.
2.
3.
Task 6: Describe the structure of DNA by filling in the gaps.
DNA is a ………………………………………………… shape. This means it is made of 2 strands held
together. DNA is made up of ………………… bases. Adenine always pairs with ……………………
Cytosine always pairs with …………………………… We say the pairs are ……………………………………
The DNA keeps its double helix shape because the bases are held together by weak
…………………………… bonds. There are …………… hydrogen bonds holding adenine and thymine
together. There are ……………………… hydrogen bonds holding cytosine and guanine
together. The backbone of DNA is made of alternating sugar and ……………………………
groups.
Task 7: DNA extraction experiment
1. Why did we add the strawberry cells to detergent (washing up liquid)?
…………………………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………………………………
2. Why did you filter the mixture?
…………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………
3. Draw a scientific diagram of how you filtered the mixture. Draw this below.
4. Why did you use the ethanol at the end of the experiment? What did you see?
…………………………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………………………………
Task 8: Cystic fibrosis is a nasty genetic disorder. It is inherited from parents passing down
genes. It is a recessive disorder – you need two faulty recessive alleles to have cystic
fibrosis (cc)
Complete the punnet square to show if two heterozygous parents can have a cystic fibrosis
child.
Mother’s gametes
Father’s
gametes
1. What is the probability that the couple will have a cystic fibrosis child. ……………………
2. What is the percentage chance they will have a cystic fibrosis child………………………
3. What is the ratio of normal offspring to cystic fibrosis offspring…………………………
Task 9: Pedigree analysis
Task 10: Describe how sex (gender) is determined in humans by completing the gap fill.
To be a …………………………… you have two ……………… chromosomes. To be a male you have an ………
and a ………… chromosome. Female eggs can only contain an ………… chromosome. Male ………………
cells can contain an X or a Y chromosome. If an egg (X) is fertilised by an X sperm, the child
will be a …………………… If an egg (X) is fertilised by an Y sperm, the child will be a ……………………
Task 11: Complete the variation revision task – ask miss for the sheet.