CIE iGCSE Co-Ordinated Science B10. Diseases and immunity Exam Style Questions Paper 4
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B16.2 — Cell division
• Topic B16.3 — Monohybrid inheritance
• Topic B10.1 — Diseases and immunity
▶️ Answer/Explanation
(a)(i) Any two from:
- growth
- repair of damaged tissues / repair of damaged organs
- replacement of cells
Mitosis produces genetically identical daughter cells for growth, repair, and replacement of worn-out cells. It ensures that each new cell receives an exact copy of the genetic material.
(a)(ii) replication (of chromosomes) / replication (of DNA)
Before mitosis begins, DNA replication occurs so that each chromosome is duplicated and consists of two identical chromatids. This ensures each daughter cell receives a complete set of genetic material.
(b)
Mitosis produces identical diploid daughter cells for growth and repair. Meiosis produces genetically different haploid cells (gametes) for sexual reproduction. Both processes involve chromosome separation. Pollen is produced by meiosis in plants.
(c) Any one from:
- antigens on the pathogen stimulate lymphocytes to produce antibodies
- antibodies bind to antigens leading to direct destruction of pathogens
- antibodies mark pathogens for destruction by phagocytes
AND memory cells are produced that give long-term active immunity.
When a pathogen infects the body, its antigens trigger an immune response. Specific lymphocytes produce antibodies that bind to antigens. After infection, memory cells remain in the body, allowing a rapid response to future infections by the same pathogen.
Question
• prostate gland.
(i) State what is meant by a chromosome.
(ii) State the name of the type of nucleus that only contains a single set of chromosomes.
(i) Complete the sentences about the way doctors treat gonorrhoea bacterial infections. Choose words from the list.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B15.4 — Sexual reproduction in humans (Parts (a) & (b))
• Topic B16.1 — Chromosomes and genes (Part (c)(i) & (c)(ii))
• Topic B10.1 — Diseases and immunity (Part (d)(i) & (d)(ii))
▶️ Answer/Explanation
(a) Urethra = C; Prostate gland = G.
The urethra is the tube that carries both urine and semen out of the body. The prostate gland is located just below the bladder and secretes fluid that nourishes and protects sperm.
(b) Completed table:
(c)(i) A chromosome is a length of DNA that contains genetic information in the form of genes.
Chromosomes are structures found in the nucleus that carry hereditary information.
(c)(ii) Haploid.
A haploid nucleus contains a single set of chromosomes (23 chromosomes in humans), as found in gametes (sperm and egg cells).
(d)(i) Doctors always use antibiotics to treat gonorrhoea infections. This increases the risk of bacteria with mutations being selected for and forming a population of resistant bacteria.
Antibiotics kill bacteria, but random mutations can produce bacteria that are resistant. These resistant bacteria survive and reproduce, leading to a population of antibiotic-resistant bacteria.
(d)(ii) Two ways to control the spread of gonorrhoea:
• Reducing the number of sexual partners / abstaining from sexual activity.
• Using condoms / preventing the transfer of bodily fluids during sex.
• Regular testing and early treatment of infected individuals.
• Partner notification and treatment.