GCSE Biology Topic 5 – Health, Disease & Development of Medicines

30 question-and-answer flashcards covering key concepts from Edexcel GCSE Biology Topic 5: health, disease, pathogen spread, immunity, antibiotics, aseptic technique, drug development, monoclonal antibodies, lifestyle factors and cardiovascular treatments.

What is the World Health Organisation’s (WHO) definition of health?

A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.

Communicable diseases can be transferred between individuals; non-communicable diseases cannot be passed from person to person and usually have genetic or lifestyle causes.

How do communicable diseases differ from non-communicable diseases?

Any two of: cardiovascular disease, asthma, diabetes, many cancers.

Give two examples of non-communicable diseases.

HIV destroys white blood cells, weakening the immune system so ‘opportunistic’ pathogens can cause infections more easily.

Why does having HIV increase susceptibility to other infections?

An organism that causes disease.

Define a pathogen.

They invade cells, use the cell’s biochemistry to replicate, then burst (lysis), destroying cells and releasing more viruses.

How do viruses cause illness inside host organisms?

Bacteria.

Which pathogen type reproduces by binary fission and produces toxins that damage cells?

Vibrio cholerae; spread through contaminated water.

Name the pathogen that causes cholera and state its method of spread.

Plasmodium species (e.g., P. falciparum); transmitted by an animal vector, the Anopheles mosquito.

What pathogen causes malaria and how is it transmitted?

Direct contact, by water, by air (including droplet infection).

List three common methods by which pathogens are spread.

It makes individuals immune, so they can’t become infected or transmit the pathogen, producing herd immunity when many are vaccinated.

How can vaccination reduce the spread of disease in a population?

1) Viral DNA replicates using host machinery; 2) New virus particles are assembled; 3) Host cell bursts (lysis); 4) Viruses infect nearby cells and cycle repeats.

Outline the four main stages of the lytic viral replication pathway.

It is caused by a bacterium; untreated infection can lead to infertility.

Chlamydia: What type of pathogen causes it, and what can untreated infection lead to?

Any two of: thick cellulose cell wall, waxy cuticle, bark, closing of stomata.

State two physical plant barriers that protect against pathogens.

They use monoclonal antibodies to detect specific pathogens present in plant tissue samples.

What is the role of ELISA kits in diagnosing plant disease?

They are enzymes in white blood cells (and tears/saliva) that break down bacterial cell walls, killing the bacteria.

How do lysozymes function as a human chemical defence?

The process in which white blood cells engulf and digest pathogens, destroying them.

What is phagocytosis?

Antibodies bind to complementary antigens on pathogens, causing them to clump so phagocytes can engulf them more easily, and they trigger memory lymphocyte formation.

How do antibodies help eliminate pathogens during the specific immune response?

When a large proportion of a population is immunised, the spread of a pathogen is greatly reduced, protecting even unvaccinated individuals.

Explain ‘herd immunity’.

Antibiotics target bacterial cell processes; viruses use host cell machinery, which antibiotics do not disrupt.

Why are antibiotics ineffective against viruses?

To prevent contamination by unwanted microorganisms that could out-compete or mutate into harmful pathogens.

What is the purpose of sterilising Petri dishes and culture media before use in aseptic technique?

Area = π r², where r is the radius of the clear zone.

Write the formula used to calculate the cross-sectional area of a bacterial inhibition zone.

The mould Penicillium; discovered by Alexander Fleming.

From which organism was penicillin first discovered, and by whom?

So neither doctors nor patients know who receives the drug or placebo, preventing bias in recording and interpreting results.

During clinical trials, why is a double-blind design used?

A fused cell formed from a mouse lymphocyte (produces antibodies) and a tumour cell (divides rapidly), used to clone identical antibody-producing cells.

What is a hybridoma cell in monoclonal antibody production?

Mobile antibodies with blue beads bind to hCG in urine; the complex moves to stationary antibodies, creating a blue line that indicates pregnancy.

Describe one way monoclonal antibodies are used in pregnancy testing.

High caloric/saturated-fat diet and low physical activity (sedentary lifestyle).

Give two lifestyle factors that contribute to obesity.

BMI = mass (kg) ÷ height² (m²); a BMI over 30 is classified as obese.

How is Body Mass Index (BMI) calculated, and what value classifies obesity?

A coronary artery bypass graft (CABG).

What surgical procedure can bypass blocked coronary arteries?

Advantage: They target only specific cells, sparing healthy tissue. Disadvantage: They are expensive and can be difficult to attach to drugs.

Name one advantage and one disadvantage of using monoclonal antibodies in medicine.