Biology Chapter 4 Quiz

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Questions and Answers

Which of the following accurately describes what a mutation is?

A process of cell division

An alteration in the DNA sequence (correct)

The transfer of genetic material between organisms

A type of protein synthesis

What is the central dogma of molecular biology?

DNA to RNA to Protein (correct)

DNA to Protein to RNA

RNA to DNA to Protein

Protein to DNA to RNA

In genetics, which term describes organisms with identical alleles at a gene locus?

Homozygous (correct)

Recessive

Heterozygous

Dominant

Which of the following statements correctly differentiates between dominant and recessive traits?

Dominant traits are expressed even if only one allele is present. Signup and view all the answers

What can be concluded about co-dominance in genetics?

Both alleles are expressed equally in the phenotype. Signup and view all the answers

What is the total number of chromosomes in a normal human cell?

46 Signup and view all the answers

What does the failure of segregation of chromatids during cell division cycle result in?

Aneuploidy Signup and view all the answers

Which section of the examination contains objective questions?

Section A Signup and view all the answers

What is the marking scheme for each objective question?

2 marks each Signup and view all the answers

How many very short answer questions are included in the exam?

2 Signup and view all the answers

What happens if a student fails to complete the exam?

They must wait until the end of the exam. Signup and view all the answers

In which part of the examination do students write long answer questions?

Questions 15 to 16 Signup and view all the answers

What must students choose when answering objective questions?

Select the correct option (a, b, c, d). Signup and view all the answers

Which condition is caused by the substitution of glutamic acid by valine in the beta globin chain of hemoglobin?

Sickle cell anaemia Signup and view all the answers

What type of genetic disorder is Thalassemia?

An autosome linked recessive blood disease Signup and view all the answers

Who is credited with the discovery of Down's syndrome?

Langdon Down Signup and view all the answers

What disorder is characterized by the absence of one X chromosome in an individual?

Turner’s Syndrome Signup and view all the answers

Who first identified DNA as an acidic substance present in the nucleus?

Friedrich Meischer Signup and view all the answers

What is the haploid content of human DNA?

3.3 × 10^9 bp Signup and view all the answers

What sugar is found in DNA?

Deoxyribose Signup and view all the answers

Which pair correctly matches two nucleobases in DNA?

Adenine pairs with Thymine Signup and view all the answers

Study Notes

General Instructions

The exam is comprised of 16 questions.
All questions are compulsory.
There are 10 objective, 2 very short answer, 2 short answer and 2 long answer questions.
Each objective and very short answer question is worth 2 marks.
Each short answer question is worth 3 marks.
Each long answer question is worth 5 marks.
There is no negative marking for incorrect answers.

Section A: Objective Questions

The total number of chromosomes in a normal human cell is 46 (23 pairs).
Failure of segregation of chromatids during cell division cycle results in the gain or loss of chromosomes called aneuploidy.
Sickle cell anaemia is caused by the substitution of glutamic acid by valine at the sixth position of the beta globin chain of the haemoglobin molecule.
Thalassemia is an autosome linked recessive blood disease.
Down syndrome was discovered by Langdon Down.
Turner’s Syndrome is caused by the absence of one of the X chromosomes, resulting in a 45 XO configuration.
DNA was first identified as an acidic substance present in the nucleus by Friedrich Miescher.
The haploid content of human DNA is 3.3×109 base pairs.
The sugar present in DNA is deoxyribose.
Adenine pairs with thymine, and guanine pairs with cytosine.

Section B: Very Short Answer Questions

Mutation is a permanent change in the DNA sequence.
Central Dogma describes the flow of genetic information from DNA to RNA to protein.

Section C: Short Answer Questions

Dominance: The expression of one allele masks the expression of another allele.
Recessive: An allele whose expression is masked by a dominant allele.
Homozygous: An individual with two identical alleles for a particular trait.
Heterozygous: An individual with two different alleles for a particular trait.
Monohybrid cross: A cross between two individuals that differ in only one trait.
Dihybrid cross: A cross between two individuals that differ in two traits.
Co-dominance: The expression of both alleles in a heterozygous individual.
- Example: AB blood group in humans.
Incomplete dominance: Neither allele completely masks the other, resulting in a blended phenotype.
- Example: Pink flower color in snapdragons.

Section D: Long Answer Questions

Law of Dominance: In a monohybrid cross, one allele (dominant) masks the expression of another allele (recessive).
- This is demonstrated using a cross between two heterozygous individuals, resulting in a 3:1 phenotypic ratio.
Double-helix structure of DNA:
- DNA is a double-stranded helix with two antiparallel strands.
- The two strands are held together by hydrogen bonds between complementary base pairs: adenine with thymine, and guanine with cytosine.
- The sugar-phosphate backbone is on the outside of the helix, while the bases are on the inside.
- The DNA helix is right-handed, meaning it twists in a clockwise direction.
- The diameter of the DNA helix is about 2 nanometers.

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Description

Test your knowledge on human genetics and chromosomal disorders with this quiz focused on Chapter 4. It covers essential concepts such as aneuploidy, sickle cell anaemia, and Turner’s Syndrome. Answer a mix of objective, short, and long questions to demonstrate your understanding.