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Biology for IGCSE & O level - Inheritance (Section 8)

1
In codominance, how do the alleles interact?
Answer
(C)
Both alleles are fully expressed.
2
Which event leads to genetic variation in meiosis?
Answer
(C)
Crossing over
3
What is the expected phenotypic ratio of a monohybrid cross (Tt x Tt) where T is dominant?
Answer
(B)
3:1
4
What is the name for the process where homologous chromosomes exchange genetic material?
Answer
(C)
Crossing over
5
What is the main purpose of meiosis?
Answer
(C)
To produce gametes with half the number of chromosomes.
6
Which of the following are true about the alleles?
Answer
A
D
7
What is the function of DNA polymerase?
Answer
(C)
To replicate DNA.
8
If a mother is a carrier for an X-linked recessive trait, what is the probability her son will be affected?
Answer
(C)
50%
9
Which of the following are steps involved in Meiosis I? (Select all that apply)
Answer
A
B
C
10
Which of the following statements are true regarding Meiosis I? (Select all that apply)
Answer
A
C
D
11
In a cross between two heterozygous individuals (Aa x Aa), what proportion of the offspring will also be heterozygous?
Answer
(C)
50%
12
What is the difference between a haploid and a diploid cell?
Answer
(A)
Haploid cells have half the number of chromosomes as diploid cells.
13
In which cellular location does translation occur in prokaryotic cells?
Answer
(C)
Cytoplasm
14
Which of the following is the correct sequence of events in protein synthesis?
Answer
(A)
Transcription → translation → amino acid sequence.
15
In a pedigree, what does a circle represent?
Answer
(B)
A female
16
Which of the following molecules is directly involved in the process of transcription?
Answer
(D)
RNA polymerase
17
Which of the following is NOT a feature of a pedigree diagram?
Answer
(D)
Dotted lines connect offspring to their parents.
18
Which of the following events occur in Prophase I of Meiosis?
Answer
(B)
Homologous chromosomes pair up
19
What is the result of Meiosis II?
Answer
(D)
Four haploid cells
20
Which of the following statements correctly describes the role of DNA in protein synthesis? (Select all that apply)
Answer
A
C
D
21
Which of the following statements are true about the law of independent assortment?
Answer
A
C
D
22
Which of the following is a key difference between autosomal and sex-linked inheritance?
Answer
(C)
Sex-linked traits show different inheritance patterns based on sex.
23
What would be the probable result of a cross between a plant with red flowers (RR) and a plant with white flowers (rr), assuming incomplete dominance?
Answer
(C)
All offspring will have pink flowers.
24
Which of the following is the most likely reason that males are more susceptible to X-linked recessive disorders?
Answer
(A)
Males only have one X chromosome.
25
In humans, which parent determines the sex of the offspring?
Answer
(B)
The father
26
What is the final result of Meiosis?
Answer
(C)
Four genetically different cells.
27
What is the expected phenotypic ratio for a dihybrid cross (AaBb x AaBb)?
Answer
(C)
9:3:3:1
28
Which of the following are true about genes?
Answer
A
C
D
29
What is the role of mRNA in protein synthesis?
Answer
(A)
To carry the genetic code from the nucleus to the ribosomes.
30
In which stage of the cell cycle does DNA replication occur?
Answer
(B)
S phase
31
In a pedigree diagram, what does a half-shaded symbol represent?
Answer
(C)
A carrier of the trait.
32
What is the function of the terminator sequence in transcription?
Answer
(B)
To signal the end of transcription.
33
What is the main function of the centromere in a chromosome?
Answer
(B)
To hold sister chromatids together
34
Which of the following is the product of transcription?
Answer
(C)
mRNA
35
What is the expected genotypic ratio from a cross between two individuals, one homozygous dominant (AA) and one homozygous recessive (aa)?
Answer
(D)
4:0
36
What is the difference between a gene and a chromosome?
Answer
(A)
A gene is a segment of a chromosome.
37
In an X-linked recessive disorder, which parent(s) must contribute the affected allele for a daughter to express the disorder?
Answer
(C)
Both the mother and the father.
38
What does the term 'locus' refer to?
Answer
(A)
The location of a gene on a chromosome.
39
Which process leads to genetic variation by creating new combinations of alleles?
Answer
(B)
Meiosis
40
What is the process by which DNA makes a copy of itself?
Answer
(C)
Replication
41
What is a key function of meiosis?
Answer
(C)
To reduce the chromosome number in gametes
42
Which of the following is an example of an X-linked recessive trait?
Answer
(C)
Color blindness
43
What is the difference between a gene and an allele?
Answer
(B)
An allele is a variant form of a gene.
44
Which of the following is an example of a somatic cell?
Answer
(C)
A skin cell
45
In what part of the cell does transcription occur?
Answer
(C)
Nucleus
46
What are the key stages of the cell cycle? (Select all that apply)
Answer
A
B
C
D
47
Which type of cell division results in cells with half the number of chromosomes?
Answer
(C)
Meiosis
48
What is the function of the ribosome?
Answer
(B)
To translate mRNA into protein.
49
What is the relationship between DNA and RNA?
Answer
(A)
RNA is a copy of DNA.
50
Which of the following is the correct genotype for a homozygous recessive individual?
Answer
(C)
aa