NSC Life Sciences DNA: The Code of Life: Various options are provided as

Question

Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A to D) next to the question numbers (1.1.1 to 1.1.1 D).

1.1.1 Which ONE of the following is a reproductive isolation mechanism?
A. Breeding at the same time of the year
B. Attraction to the same pollinators
C. Prevention of fertilisation
D. Sharing the same habitat

1.1.2 The scientists who won the Nobel Prize for the discovery of the structure of DNA were ...
A. Watson and Franklin.
B. Wilkins and Franklin.
C. Crick and Wilkins.
D. Watson and Crick.

1.1.3 In a dihybrid cross, an animal with long ears (E) and red fur (R) was crossed with an animal with short ears (e) and black fur (r).
Which ONE of the following could represent the genotypes of the parents?
A. EE Rr x ee rr
B. Ee Rr x Ee rr
C. Ee Rr x eE KEE
D. EeEe x EE Rr

1.1.4 Which ONE of the following reduces genetic variation in the offspring?
A. Mutations
B. Random mating
C. Cloning
D. Random fertilisation

1.1.5 This process is best explained as a process that produces ... daughter cells.
A. Two haploid
B. Two diploid
C. Four diploid
D. Four haploid

1.1.6 Colour-blindness is a disorder caused by a recessive allele on the X chromosome. Which of the following describes the genotype of a colour-blind person?
A. X^c X^Y
B. X^X X^Y
C. X^c X^X
D. X^c Y

1.1.7 The study of the inheritance of mutations in mitochondrial DNA is an example of ...
A. fossil evidence.
B. gametic evidence.
C. modification by descent.
D. cultural evidence.

1.2 Give the correct biological term for each of the following descriptions.
Write only the term next to the question numbers (1.2.1 to 1.2.9) in the ANSWER BOOK.

1.2.1 The bonds that hold the two strands of a DNA molecule together

1.2.2 A genetic cross involving one gene and its alleles

1.2.3 Undifferentiated cells that may form any other cell in the human body

1.2.4 The structures in the cell that form the spindle fibres

1.2.5 The phase of meiosis when chromosomes are aligned at the equator

1.2.6 A genetic disorder where blood does not clot

1.2.7 The discovery of new species

1.2.8 Evolution characterised by long periods of no change alternating with short periods of rapid change

1.2.9 The study of heredity and variation in organisms

1.3 Indicate which of the descriptions in COLUMN I apply to ONLY B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write ONLY A, B, BOTH A and B or NONE next to the question numbers (1.3.1 to 1.3.3) in the ANSWER BOOK.

COLUMN I                          COLUMN II
1.3.1 Found in the nucleus           A. DNA
1.3.2 Found in the cytoplasm        B. RNA
1.3.3 Site of meiosis in humans     C. Metaphase
                                   D. Testis

1.4 The diagram below represents a pair of homologous chromosomes in a plant cell. The alleles for two characteristics, seed colour (G and g) and plant height (T and t), are indicated on the chromosomes.

1.4.1 Give the term used to describe the position of an allele on a chromosome.

1.4.2 Identify parts A and C.

1.4.3 Name the process during which parts A and B exchange genetic material.

1.4.4 During which phase of meiosis does the process named in QUESTION 1.4.3 take place?

1.4.5 State the following for this plant:
(a) Genotype
(b) The characteristic that is homozygous recessive

1.5 The diagram below represents some nucleotides in a single strand of DNA.

1.5.1 Give the LETTER of the part that represents a:
(a) Sugar molecule
(b) Phosphate molecule

1.5.2 How many nucleotides are represented in the diagram?

1.5.3 Write down the nitrogenous bases (from top to bottom as indicated) of the complementary DNA strand of this molecule.

1.5.4 Name TWO processes that require the two strands of a DNA molecule to separate into single strands as shown in the diagram.

1.6 The table below shows the blood groups of the members of a family. Two of the children are biological offspring of the parents and one child is adopted.

FAMILY MEMBER                  BLOOD GROUP
Father                                   A
Mother                                 AB
Daughter                             O
Son 1                                   B
Son 2                                   A

1.6.1 How many:
(a) Different phenotypes for blood group appear in this family
(b) Possible genotypes are there for blood group AB

1.6.2 Give the genotype of the father.

1.6.3 Which member of the family:
(a) Has the genotype ii
(b) Has co-dominant alleles
(c) Is adopted

Various options are provided as possible answers to the following questions - NSC Life Sciences - Question 1 - 2021 - Paper 2

Worked Solution & Example Answer:Various options are provided as possible answers to the following questions - NSC Life Sciences - Question 1 - 2021 - Paper 2

1.5.1 Give the LETTER of the part that represents a: (a) Sugar molecule

1.5.1 Give the LETTER of the part that represents a: (b) Phosphate molecule

1.5.2 How many nucleotides are represented in the diagram?

1.5.3 Write down the nitrogenous bases (from top to bottom as indicated) of the complementary DNA strand of this molecule.

1.5.4 Name TWO processes that require the two strands of a DNA molecule to separate into single strands as shown in the diagram.

1.6.1 How many: (a) Different phenotypes for blood group appear in this family

1.6.1 How many: (b) Possible genotypes are there for blood group AB

1.6.2 Give the genotype of the father.

1.6.3 Which member of the family: (a) Has the genotype ii

1.6.3 Which member of the family: (b) Has co-dominant alleles

1.6.3 Which member of the family: (c) Is adopted

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