3.1 The diagram below shows the arrangement of two pairs of homologous chromosomes in a cell undergoing meiosis - English General - NSC Life Sciences - Question 3 - 2017 - Paper 2
Question 3
3.1 The diagram below shows the arrangement of two pairs of homologous chromosomes in a cell undergoing meiosis.
State TWO characteristics of homologous chromosomes... show full transcript
Worked Solution & Example Answer:3.1 The diagram below shows the arrangement of two pairs of homologous chromosomes in a cell undergoing meiosis - English General - NSC Life Sciences - Question 3 - 2017 - Paper 2
Step 1
State TWO characteristics of homologous chromosomes.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Homologous chromosomes are similar in length and shape.
They carry genes for the same characteristics at corresponding loci.
Step 2
Identify structure A.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Structure A is the spindle fiber.
Step 3
How many of EACH of the following is present in the diagram?
(a) Chromatids
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
(a) There are 8 chromatids present in the diagram.
Step 4
(b) Centromeres
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
(b) There are 4 centromeres present in the diagram.
Step 5
Draw a labelled diagram to show ONE of the cells that would be formed at the end of telophase I.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The diagram should include a cell with two replicated chromosomes, cell membrane, centrioles, chromosome labels, etc.
Step 6
Give the genotype of the:
(a) Individual represented in the diagram
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
(a) The genotype of the individual represented in the diagram is RrTt.
Step 7
(b) Possible gametes resulting from the arrangement of alleles represented in the diagram.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
(b) The possible gametes from the arrangement are RT, Rt, rT, rt.
Step 8
Determine the genotypes and phenotypes of their parents by doing a genetic cross.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The phenotypes of the parents are Blood type A and Blood type B. Their genotypes are I^A i (for the father) and I^B i (for the mother).
Step 9
Identify the technique shown above.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The technique shown is DNA profiling (or DNA fingerprinting).
Step 10
Which male is the biological father of the child?
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Male 3 is the biological father of the child.
Step 11
Explain your answer to QUESTION 3.3.2.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The bands of the child's DNA are a combination of the DNA from each parent. The bands from Male 3 align perfectly with the child's bands, indicating a match.
Step 12
State TWO other uses of this technique.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This technique can be used to identify organisms from their remains.
It is useful for identifying missing persons.
Step 13
What is the process called where wheat plants are altered by the insertion of genes?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The process is called genetic engineering or recombinant DNA technology.
Step 14
State ONE other disadvantage of using insecticides.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Insecticides can kill other beneficial organisms, harming the ecosystem.
Step 15
State TWO ways in which scientists could have improved the validity of this investigation.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Use the same field for both experiments to minimize environmental variance.
Use the same number and species of wheat plants for both cases.
Step 16
What was the crop yield, in arbitrary units, of wheat plants without the insecticide gene grown in a greenhouse?
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The crop yield was 50 arbitrary units.
Step 17
Calculate the difference in yield between the wheat with the insecticide gene and the wheat without the insecticide gene grown in the field. Show ALL working.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Difference in yield = Yield with insecticide gene - Yield without insecticide gene = 70 - 45 = 25.
Step 18
Describe the difference in results for the wheat with the insecticide gene grown in a greenhouse and the wheat in a field.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
In the greenhouse, wheat with the insecticide gene showed high yield, whereas wheat grown in the field showed lower yield due to varying environmental conditions.
Step 19
Suggest ONE possible reason for the difference described in QUESTION 3.4.6.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The controlled conditions in the greenhouse can optimize growth factors, unlike the variability in field conditions.
Step 20
Give TWO possible reasons why farmers may be against the use of these insecticide-producing plants.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Potential health impacts on consumers due to pesticide residues.
Concerns about environmental harm and interfering with natural ecosystems.