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Biology questions, chapter 11
Nama / NameKelas / ClassTarikh / Date

Inheritance

45 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

Which statement describes monohybrid inheritance?
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B
Monohybrid inheritance involves one characteristic with contrasting traits controlled by one gene. Two characteristics is dihybrid inheritance.
For the teacher: Remembering, low difficulty, standard 11.1
Textbook p. 230
2

Question 2

Which of the following is a trait?
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C
A trait is a variation of a characteristic. Height, flower colour and blood group are characteristics; dwarf is a trait of height.
For the teacher: Remembering, low difficulty, standard 11.1
Textbook p. 232
3

Question 3

A homozygous dominant genotype for flower colour is BB. What is a genotype with different alleles called?
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A
Bb has two different alleles, so it is a heterozygote. A purebreed has two identical alleles.
For the teacher: Understanding, low difficulty, standard 11.1
Textbook p. 233
4

Question 4

A heterozygous tall pea plant (Tt) is crossed with a dwarf plant (tt). What is the phenotypic ratio of the offspring?
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D
Gametes T, t and t, t give Tt, Tt, tt, tt: 1 tall : 1 dwarf.
For the teacher: Applying, low difficulty, standard 11.1
Textbook p. 235
5

Question 5

Which statement is Mendel's First Law?
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B
The Law of Segregation: a pair of alleles separates, so each gamete carries one allele. Option A is the Second Law.
For the teacher: Understanding, low difficulty, standard 11.1
Textbook p. 237
6

Question 6

A round, yellow pea plant (RrYy) is crossed with a constricted, green pea plant (rryy). R is the dominant allele for round and Y for yellow. Which phenotypes are produced in the offspring?
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A
RrYy gives gametes RY, Ry, rY and ry; rryy gives only ry. Offspring: RrYy, Rryy, rrYy and rryy, so all four phenotypes in a ratio of 1 : 1 : 1 : 1.
For the teacher: Applying, low difficulty, standard 11.2
Textbook p. 239
7

Question 7

How many different types of gametes are produced by a plant with the genotype AaBb?
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D
AB, Ab, aB and ab: 4 types of gametes.
For the teacher: Applying, low difficulty, standard 11.2
Textbook p. 238
8

Question 8

A couple has a child with blood group O. The father is blood group A and the mother is blood group B. What are the genotypes of the parents?
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C
The child IO IO received one IO from each parent, so both parents are heterozygous: IA IO (group A) and IB IO (group B).
For the teacher: Applying, medium difficulty, standard 11.4
Textbook p. 245
9

Question 9

What is a locus?
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A
A locus is the specific location of a gene on a chromosome. An alternative form of a gene is an allele.
For the teacher: Understanding, low difficulty, standard 11.3
Textbook p. 240
10

Question 10

A female with Turner syndrome has how many chromosomes in her body cells?
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D
Turner syndrome is 44 + XO: one X chromosome is missing, so there are 45 chromosomes.
For the teacher: Remembering, low difficulty, standard 11.4
Textbook p. 244
11

Question 11

A colour blind boy has parents with normal eyesight. Which genotype must his mother have? (XB is normal, Xb is colour blind.)
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B
The boy (Xb Y) got Xb from his mother. She has normal eyesight, so she must be a carrier, XB Xb. His father (XB Y) gave him the Y chromosome.
For the teacher: Analysing, medium difficulty, standard 11.4
Textbook p. 248
12

Question 12

Which couple can have a rhesus negative child?
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C
A rhesus negative child is Rh−Rh−, so each parent must carry an Rh− allele. Only option C has two parents who both carry Rh−; both are heterozygous: Rh+Rh− and Rh+Rh−.
For the teacher: Applying, low difficulty, standard 11.4
Textbook p. 246

Section B: structured questions

33 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Mendel crossed a purebreed tall pea plant with a purebreed dwarf pea plant. All the F1 plants were tall. The F1 plants were then self-pollinated to produce the F2 generation.
[1 mark] (a)State one reason why Mendel chose the pea plant for his experiments.
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Any 1 points
Tick each point you got.
[2 marks] (b)Which trait is recessive? Give a reason.
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[3 marks] (c)Mendel obtained 787 tall plants and 277 dwarf plants in his F2 generation. Calculate the ratio of tall to dwarf plants to two decimal places and explain why it is not exactly 3 : 1.
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For the teacher: Understanding, low difficulty, standard 11.1
Textbook p. 231
14

Question 14

A pea plant with purple flowers and inflated pods (PPSS) is crossed with a plant with white flowers and constricted pods (ppss). P is the dominant allele for purple and S the dominant allele for inflated pods. Two plants of the F1 generation are then crossed to produce 16 F2 progeny.
[2 marks] (a)State the genotype and phenotype of the F1 generation.
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Tick each point you got.
[1 mark] (b)State the probability of an F2 plant with purple flowers and constricted pods.
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[1 mark] (c)State the phenotypic ratio of the F2 generation (purple inflated : purple constricted : white inflated : white constricted).
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Tick each point you got.
[2 marks] (d)State Mendel's Second Law.
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For the teacher: Applying, low difficulty, standard 11.2
Textbook p. 252
15

Question 15

A man with normal eyesight (XB Y) marries a woman who is colour blind (Xb Xb). XB is the dominant allele for normal eyesight and Xb is the recessive allele for colour blindness.
[3 marks] (a)Draw a schematic diagram to show the genotypes of their children.
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[1 mark] (b)State the probability that a child is colour blind.
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[2 marks] (c)Explain why colour blindness is more common in males than in females.
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For the teacher: Analysing, medium difficulty, standard 11.4
Textbook p. 252
16

Question 16

Diagram 1 shows the pedigree of a family for haemophilia.
Pedigree chart: generation I has a normal father (square) and a carrier mother (circle with dot); generation II has a carrier daughter, a normal daughter, a haemophilic son (filled square) and a normal son
Diagram 1
[2 marks] (a)State the genotype of I-2 and of II-3. Use XH and Xh.
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Tick each point you got.
[2 marks] (b)From which parent did II-3 inherit the haemophilia allele? Explain.
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For the teacher: Analysing, medium difficulty, standard 11.4
Textbook p. 250
17

Question 17

Diagram 2 shows the pedigree for the type of earlobe in a family. Free earlobe is dominant (E) and attached earlobe is recessive (e).
Pedigree chart: a father and mother with free earlobes have a son with free earlobes, a daughter with attached earlobes (filled circle) and a daughter with free earlobes
Diagram 2
[1 mark] (a)What is the genotype of the daughter with attached earlobes?
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Tick each point you got.
[3 marks] (b)The parents both have free earlobes. Explain how the daughter has attached earlobes.
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[1 mark] (c)State the probability that the next child has attached earlobes.
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For the teacher: Analysing, high difficulty, standard 11.4
Textbook p. 249
18

Question 18

Nondisjunction during meiosis can cause genetic disorders such as Down syndrome.
[1 mark] (a)What is nondisjunction?
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[1 mark] (b)A gamete with 24 chromosomes fertilises a normal gamete. State the number of chromosomes in the zygote.
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For the teacher: Understanding, low difficulty, standard 11.4
Textbook p. 243
19

Question 19

In cattle, white face (W) and long horns are dominant over black face (w) and short horns. A breeder wants a herd with all white-faced cattle, but he does not know whether his white-faced bull is purebreed or hybrid.
[2 marks] (a)Suggest how he can find out. State the genotype of the cow that he should use.
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Tick each point you got.
[2 marks] (b)State the result that shows that the bull is purebreed and the result that shows that it is a hybrid.
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Tick each point you got.
For the teacher: Evaluating, medium difficulty, standard 11.1
Textbook p. 253