Biology Comprehensive Practice Test 4

Questions

100

Marks

Sections

100%

Auto-Graded

Section	Questions	Marks each	Total marks
A — Multiple Choice	15	2	30
B — True / False	10	2	20
C — Fill in the Blank	10	2	20
D — Column Matching	5 pairs	2	10
E — Short Answer	5	4	20
Total	45	—	100

Fill-in-the-blank answers are checked against accepted spellings of the key term. Short answers are marked against a marking guide: write a full answer (at least 8 words) and you earn marks for each key idea you include. After you submit, every question shows the correct answer with a short explanation.

Section A — Multiple Choice

30 marks

15 questions · 2 marks each. Choose the best answer.

1.Bacteria are generally classified as:Basic2 pts

A. Eukaryotic animals

B. Viruses with nuclei

C. Prokaryotic cells

D. Multicellular fungi

Why: The correct answer is C. Bacterial cells have no nucleus or other membrane-bound organelles, so they are prokaryotic.

2.Viruses are best described as:Basic2 pts

A. Independent cells with ribosomes that divide on their own

B. Acellular infectious agents that depend on host cells to replicate

C. Photosynthetic bacteria found in water

D. Multicellular parasites that live in the gut

Why: The correct answer is B. Viruses are not cells. They can reproduce only by using the machinery of a host cell.

3.A pathogen is:Basic2 pts

A. Any harmless microorganism found on the skin

B. A white blood cell that fights infection

C. A vaccine ingredient in every case

D. An organism or agent capable of causing disease

Why: The correct answer is D. Pathogens include some bacteria, viruses, fungi and protists. Many microorganisms are harmless.

4.Which statement about malaria is correct?Basic2 pts

A. It is caused by a single-celled protist (Plasmodium) carried by Anopheles mosquitoes

B. It is caused by a bacterium spread through contaminated water

C. It is caused by a virus spread by respiratory droplets

D. It is caused by a fungus spread by direct skin contact

Why: The correct answer is A. Malaria is caused by Plasmodium, a protist. Female Anopheles mosquitoes act as vectors.

5.Which of these diseases is caused by a virus?Basic2 pts

A. Tuberculosis

B. Malaria

C. Influenza

D. Athlete's foot

Why: The correct answer is C. Influenza is viral. Tuberculosis is bacterial, malaria is caused by a protist and athlete's foot by a fungus.

6.Which measure most directly reduces the spread of cholera?Intermediate2 pts

A. Providing clean drinking water and safe disposal of sewage

B. Taking antibiotics every day as a precaution

C. Avoiding all contact with other people for life

D. Eating only cooked starchy foods

Why: The correct answer is A. Cholera is spread through water or food contaminated with the bacterium. Clean water and sanitation break that route.

7.Phagocytes help defend the body by:Intermediate2 pts

A. Producing red blood cells in the bone marrow

B. Making the hormone insulin

C. Carrying oxygen using haemoglobin

D. Engulfing and digesting microbes or debris

Why: The correct answer is D. Phagocytes are white blood cells that engulf pathogens by phagocytosis and digest them.

8.The incubation period is the time between:Intermediate2 pts

A. Vaccination and the production of antibodies

B. Infection and the appearance of the first symptoms

C. The first symptom and full recovery

D. Recovery and the next infection

Why: The correct answer is B. During incubation the pathogen is multiplying but symptoms have not yet appeared.

9.A chromosome is best described as:Intermediate2 pts

A. DNA associated with proteins and organised into a structural unit

B. A type of carbohydrate in the cell wall

C. A membrane-bound organelle without DNA

D. A single protein molecule

Why: The correct answer is A. Chromosomes are made of DNA wound around proteins, which packages long DNA molecules.

10.A gene is best understood as:Intermediate2 pts

A. An entire organism

B. A cell organelle

C. A functional DNA sequence that contributes to a biological product or its regulation

D. A droplet of stored lipid

Why: The correct answer is C. A gene is a region of DNA that carries the instructions for a product, usually a protein or an RNA molecule.

11.DNA replication is described as semiconservative because:Advanced2 pts

A. Both new DNA strands are made entirely of new material

B. Each daughter DNA molecule has one parental strand and one new strand

C. No parental DNA is kept in either daughter molecule

D. Only the proteins of the chromosome are copied

Why: The correct answer is B. Each new DNA molecule keeps one original strand and gains one newly made strand.

12.Meiosis is important in sexual reproduction because it:Advanced2 pts

A. Produces identical diploid body cells only

B. Stops chromosomes from separating

C. Removes all genetic variation

D. Produces haploid cells and contributes to genetic variation

Why: The correct answer is D. Meiosis halves the chromosome number to make gametes, and crossing over and independent assortment create new allele combinations.

13.A mutation is:Advanced2 pts

A. A change in the sequence or structure of genetic material

B. Always harmful to the organism

C. Always beneficial to the organism

D. Always caused by exercise or diet

Why: The correct answer is A. Mutations can be harmful, neutral or occasionally beneficial, depending on where they occur and the environment.

14.Both parents are heterozygous carriers (Aa) of a recessive allele. What is the chance that a child inherits two recessive alleles (aa)?Advanced2 pts

A. 0%, because both parents are unaffected

B. 50%

C. 25% (1 in 4)

D. 100%

Why: The correct answer is C. Aa × Aa gives AA, Aa, Aa and aa in equal chances, so one in four children is aa.

15.A phenotype is influenced by:Advanced2 pts

A. Genes only, in every case

B. Genotype and environment, depending on the trait

C. Environment only, in every case

D. Chromosome number only

Why: The correct answer is B. Phenotype is the observable result of the genotype and the environment acting together.

Section B — True / False

20 marks

10 questions · 2 marks each.

16.All microorganisms cause disease.Basic2 pts

True

False

Why: The answer is False. Most microorganisms are harmless, and many are useful, for example gut bacteria and yeast.

17.Some bacteria are beneficial to humans and ecosystems.Basic2 pts

True

False

Why: The answer is True. Bacteria help with digestion, decomposition and nutrient cycling.

18.Viruses generally require host cells to reproduce.Basic2 pts

True

False

Why: The answer is True. Viruses have no cell machinery of their own and use a host cell to make new virus particles.

19.A pathogen must always cause symptoms immediately after entering a host.Basic2 pts

True

False

Why: The answer is False. There is usually an incubation period, and some infections cause no symptoms.

20.Washing hands with soap can reduce the spread of some infections.Basic2 pts

True

False

Why: The answer is True. Washing removes many microbes from the skin and so reduces transmission by contact.

21.DNA contains information encoded in the sequence of its nucleotides.Intermediate2 pts

True

False

Why: The answer is True. The order of the bases A, T, C and G carries the genetic information.

22.Every mutation causes a visible disease.Intermediate2 pts

True

False

Why: The answer is False. Many mutations are neutral and have no visible effect.

23.Meiosis normally produces genetically identical daughter cells.Advanced2 pts

True

False

Why: The answer is False. Meiosis produces genetically different haploid cells. Mitosis produces identical cells.

24.A dominant allele is always more common in a population than a recessive allele.Advanced2 pts

True

False

Why: The answer is False. Dominance describes how an allele is expressed, not how common it is.

25.Genetic information can influence traits without being the only influence on every trait.Advanced2 pts

True

False

Why: The answer is True. Many traits are affected by both genes and the environment.

Section C — Fill in the Blank

20 marks

10 questions · 2 marks each. Type the missing word or term.

26.Viruses are generally described as ______ because they lack cellular organisation.Intermediate2 pts

Why: Acellular means not made of cells.

27.The spread of a pathogen from one host to another is called ______.Intermediate2 pts

Why: Transmission can be by contact, air, water, food or vectors.

28.An animal such as a mosquito that carries a pathogen from one host to another is called a ______.Intermediate2 pts

Why: A vector transmits a pathogen without necessarily being ill itself.

29.Bacteria are ______ organisms because their cells have no nucleus.Intermediate2 pts

Why: Prokaryotes lack a nucleus and membrane-bound organelles.

30.The time between infection and the first symptoms is called the ______ period.Intermediate2 pts

Why: The incubation period varies between diseases.

31.A cell containing two sets of chromosomes is described as ______.Advanced2 pts

Why: Most body cells are diploid. Gametes are haploid.

32.The process by which the information in a gene is used to make a functional product is gene ______.Advanced2 pts

Why: Gene expression includes making RNA and, for many genes, protein.

33.The genetic make-up of an organism is its ______.Advanced2 pts

Why: Genotype is the combination of alleles an organism has.

34.The observable characteristics of an organism form its ______.Advanced2 pts

Why: Phenotype results from genotype and environment.

35.Exchange of DNA between homologous chromosomes during meiosis is called ______ over.Advanced2 pts

Why: Crossing over increases genetic variation in gametes.

Section D — Column Matching

10 marks

Use the ▲ ▼ buttons to reorder Column B until each row lines up with the correct term in Column A. 2 marks per correct pair.

36–40.Match each term in Column A with the correct description in Column B.Advanced10 pts

Column A

Bacterium

Virus

Vector

Gene

Chromosome

Column B

Functional region of DNA

Carries a pathogen between hosts

DNA packaged with proteins

Prokaryotic microorganism

Acellular infectious agent

Why: A bacterium is a prokaryotic microorganism; a virus is an acellular infectious agent; a vector carries a pathogen between hosts; a gene is a functional region of DNA; a chromosome is DNA packaged with proteins.

Section E — Short Answer

20 marks

5 questions · 4 marks each. Answer in one or two full sentences (at least 8 words). Marks are given for each key idea in the marking guide.

41.Explain why the presence of a microorganism does not automatically mean that disease will occur.Advanced4 pts

42.Why can respiratory infections spread efficiently even when an infected person does not have severe symptoms?Advanced4 pts

43.Explain the relationship among DNA, genes and chromosomes.Advanced4 pts

44.Explain why meiosis is important for both chromosome-number stability and genetic variation in sexual reproduction.Advanced4 pts

45.A child has a recessive condition while both parents are unaffected. Explain a plausible inheritance pattern.Advanced4 pts