Genetics Revision (Missing Sex Linkage & Mutations)

Genetics Revision (Missing Sex Linkage & Mutations)

Part A- Multiple Choice Questions (out of 10 marks)

Circle only one answer for each of the following questions.

For the next two questions, please refer to the following information. The sequence of a strand on DNA is:

AAA TTA GGC CGC ATT

1. The complementary DNA strand to the one above is:

a) CCC GGC TTA ATA CGG

b) TTT AAT CCG GCG TAA

c) AAA TTA GGC CGC ATT

d) UUU AAU CCG GCG UAA

2. The complementary RNA strand to the one above would be:

a) TTT AAT CCG GCG TAA

b) CCC GGC TTA ATA CGG

c) UUU AAU CCG GCG UAA

d) AAA TTA GGC CGC ATT

3. A gene is:

(a) Found in the cytoplasm of a cell

(b) The rule that governs how bases pair

(d) Double stranded RNA

4. DNA is made up of all of the following except:

a) nitrogenous bases

b) protein

c) phosphate groups

d) sugar

5. Which of the following is incorrect about DNA shape and structure:

a) it has a phosphate sugar backbone

b) it is single stranded

c) it is a helix shape

d) it is double stranded

6. DNA is found in:

a) the cell wall

b) the membrane

c) the nucleus

d) the air pocket

7. Gametes

a) have 46 chromosomes

b) are a type of meat

c) include eggs and sperm

d) are homozygous

8. In garden peas, the white flower (w) is recessive to the purple (W). The genotype of a plant with purple flowers is:

a) WW or Ww

b) WW only

c) ww only

d) Ww or ww

9. A human cell has:

a) 43 chromosomes

b) 23 chromosomes

c) 46 chromosomes

d) 22 pairs of chromosomes

10. Mitosis

(a) makes haploid cells

(b) requires two cell divisions

(d) results in phenotypically different daughter cells

11. The phenotype of a person:

(a) is influenced by their environment

(b) is the product of genes alone

(d) cannot be expressed in humans

Part B- Short Answer Questions

1. Who was Gregor Mendel?

2. Label the following structures on a diagram of a cell. Give the function for each of the following organelles.

Cell membrane cytoplasm mitochondria nucleus ribosomes

3. Describe the structure and shape of the DNA molecule

4. In birds, green feather colour (G) is dominant to yellow feather colour (g). A homozygous green bird is crossed with a homozygous yellow bird.

a) Draw up a punnet square of this cross.

b) List the genotype and phenotype of the offspring.

c) Two of their offspring breed. Draw a punnet square and list the genotypes and phenotypes of all possible offspring.

5. Bases pair up in DNA.

a) Draw a diagram to show the base-pairing rule in DNA.

b) What is the name given to all 4 bases, beginning with ‘N’?

3 marks

6. What is a gamete? How many chromosomes do they have?

2 marks

7. What is an example of a eukaryotic cell? Name one major difference between eukaryotic and prokaryotic cells.

2 marks

8. What do the letters DNA stand for?

9. (a) Explain what is meant by the following processes and list where they occur in the cell.

(i) Transcription

(ii) Translation

(b) What is the role of mRNA? Explain your answer.

10. The eye colour of a fruit fly is determined by a single gene that has dominant and recessive alleles. The allele for red eyes (R) is dominant over the allele for white eyes (r).

a) Two heterozygous red eyed flies are crossed. Show the parents and a punnet square to show the outcome.

b) What proportion of the offspring would be homozygous recessive? _____

c) What proportion of the offspring would have red eyes? _____

d) What proportion of the offspring would be heterozygous? _____

e) Complete a Punnet square crossing a homozygous red eyed fruit fly with a homozygous white eyed fruit fly.

f) What can you say about the phenotypes of the offspring from the cross in part e?

11.Explain the difference between mitosis and meiosis. In your answer include the number of chromosomes at the start and at the end of each process

______

12.If a woman with brown hair (BB) and a man with blond hair (bb) had children,

a) What are the possible genotypes?

b) What are the possible phenotypes?

c) What is the probability that they will have a child with blond hair?

d) What is the probability that they will have a child with brown hair?

13.If ‘T’ is the gene for tall and ‘t’ is the gene for short and a heterozygous tall plant was crossed with a homozygous short plant,

a) What would be the possible genotypes?

b) What are the resulting phenotypes?

c) What is the probability that the plant will be tall?

d) What is the probability that the plant will be short?

14.Two individuals who are heterozygous for the dominant trait, right handedness, marry.

a) Write out the genotypes of the parents.

b) Draw a Punnet square to calculate the possible offspring these parents may produce.

15. Draw a Punnet square to show the outcome of a cross between a homozygous dominant parent and a homozygous recessive parent for the coat colour (B=black and b=white). Give the ratio for the genotype and phenotype of the offspring

16.Draw a Punnet square showing a cross between a homozygous dominant parent and a homozygous recessive parent for the coat colour (B=black and b=white). Give both the genotypic and phenotypic ratios.

17. Draw a Punnet square to show the outcome of a cross between a homozygous dominant parent and a homozygous recessive parent for the feather colour G=green and g= yellow

18.On a pedigree:

a)What symbol is used for male?

b)What is used for female?

c)What does it mean when the symbol is shaded in?

18. Examine the family pedigree below. It illustrates the pattern of inheritance of right- (R) and left-handedness (r) in a particular family. Familiarise yourself with the key before answering the questions.

Which characteristic, left- or right-handedness, is dominant in humans, and which is recessive?

19. Write down the phenotypes and genotypes for each of the following individuals (Refer to question 18)

Individual / Phenotype / Genotype
A
B
C
D
F
H

a Write down the phenotype for individuals E and G.

b List the possible genotypes for the individuals E and G.

c Explain how it is that you can be sure of the genotype for D but not for E or G.

20.What is a Sex-Linked characteristic? Give an example. What chromosome is it carried on – the X or the Y?

21. Write each of the following words next to the definition that it matches in the table below:

DNA Chromosome Genotype Phenotype

Dominant Recessive Autosomes Homozygous

Heterozygous Karyotype

Word / Definition
The full set of chromosomes for an organism, sorted into pairs in order
DNA that is tightly wound into the shape of an X
A gene whose effect masks that of another gene
Found in the nucleus of a cell
When two alleles for a given characteristic are identical
The genes an individual carries for a given characteristic
A gene whose effect is masked by that of another gene
When two alleles for a given characteristic are different
The outward appearance of an organism with respect to a given characteristic
The non-sex chromosomes

Question 22

Fill in the blanks to explain the 6 steps needed for mitosis to occur.

1. DNA is copied; this is called DNA ______.

2. DNA is wound tightly into compact chromosomes (each with two sister ______). These compact chromosomes are easier to move than the long thin chromosomes in a cell which is not undergoing cell division. Spindle fibers which will move the chromosomes begin to form.

3. Spindle fibers attach to the chromosomes and line the chromosomes up in the middle of the cell.

4. Spindle fibers pull the sister ______apart to form separate chromosomes which are moved toward opposite ends of the cell.

5. In a process called cytokinesis, the cell begins to pinch in half, with one set of chromosomes in each half.

6. Two ______cells are formed. Each ______cell has received a complete set of chromosomes. Each chromosome unwinds into a long thin thread so that genes can become active and give the instructions for making proteins.

2. For each of the figures below, give the number of the corresponding step described above. Draw arrows to indicate the sequence of events during cell division. (For simplicity, the figures show cells that have only 4 chromosomes (2 pairs of homologous chromosomes), but the basic process is the same as in human cells which have 46 chromosomes.)