2.Drugs, transport in plants, and circulatory systems

What is a drug?

any substance taken into the body that modifies or affects chemical reactions in the body.

What are antibiotics?

chemical substances made by certain fungi or bacteria that affect the working of bacterial cells, either by disrupting their structure or function or by preventing them from reproducing.

How do antibiotics affect bacterial cells?

They disrupt bacterial cell structure or function, or prevent bacteria from reproducing.

Are antibiotics effective against bacteria or viruses?

Antibiotics are effective against bacteria but not against viruses.

Why don’t antibiotics usually harm animal cells?

They target processes and structures specific to bacterial (prokaryotic) cells, which animal cells do not have.

What type of cells do antibiotics target?

Bacterial (prokaryotic) cells.

What is antibiotic resistance?

When bacteria survive and continue to reproduce despite the presence of antibiotics.

Why are antibiotics becoming less effective?

Due to overuse, incorrect prescribing, incomplete courses, and large-scale use in farming.

How does not completing an antibiotic course cause resistance?

Some bacteria survive and develop resistance, then multiply.

Why must a full antibiotic course be completed?

To ensure all bacteria are killed and resistance does not develop.

Why do antibiotics not work on viruses?

Antibiotics target structures and processes found in bacterial cells, which viruses do not have.Cell walls, cell membranes, ribosomes, and metabolic enzymes.

Why can antibiotics disrupt bacterial reproduction but not viral reproduction?

Viruses reproduce inside host cells using the host’s machinery, not their own.

How do viruses differ from bacteria in terms of cell type?

Viruses are not cells, while bacteria are prokaryotic cells.

Why don’t antibiotics affect viral protein production?

Viruses use the host cell’s ribosomes, which antibiotics do not target.

What happens if antibiotics are used to treat viral infections?

They have no effect on the virus and increase the risk of antibiotic resistance.

What is the function of xylem?

Transport water and mineral ions from roots to leaves.

What is the function of phloem?

Transport sucrose and amino acids around the plant.

Where are xylem vessels found in a vascular bundle?

On the inside.

Where are phloem vessels found?

On the outside.

How are xylem vessels adapted for transport?

Dead hollow cells lignified walls continuous tubes.

What is lignin?

A substance that strengthens xylem walls.

What are root hair cells?

Extensions of root epidermal cells.

Why are root hair cells important?

They increase surface area for absorption.

How does water enter root hair cells?

By osmosis.

What is the pathway of water through a plant?

Root hair cell root cortex xylem leaf mesophyll.

What is transpiration?

Loss of water vapour from leaves through stomata.

Why is transpiration important?

Cools plant transports minerals and maintains turgidity.

What direction does water move in xylem?

One direction from roots to leaves.

What factors affect transpiration rate?

Temperature wind speed and humidity.

How does temperature affect transpiration?

Higher temperature increases transpiration.

How does wind speed affect transpiration?

Higher wind speed increases transpiration.

What is a potometer used for?

Measuring transpiration rate.

What causes the transpiration stream?

Cohesion tension and evaporation.

What is cohesion?

Attraction between water molecules.

What is wilting?

Loss of turgor when water loss exceeds uptake.

What is translocation?

Movement of sucrose and amino acids in phloem.

What cells make up phloem?

Living cells with sieve plates.

What is a source?

Where sugars are produced.

What is a sink?

Where sugars are used or stored.

Does translocation occur in one direction?

No it occurs in multiple directions.

What is the role of the circulatory system?

To transport blood substances and heat around the body.

What components make up the circulatory system?

Blood blood vessels heart and valves.

What is a single circulatory system?

Blood passes through the heart once per circuit.

Which animals have a single circulation?

Fish.

What is a double circulatory system?

Blood passes through the heart twice per circuit.

Which animals have a double circulation?

Mammals.

What are the two circuits in mammals?

Pulmonary and systemic circulation.

What is the advantage of double circulation?

Maintains high pressure for efficient oxygen delivery.

What side of the heart pumps blood to the lungs?

The right side.

What side of the heart pumps blood to the body?

The left side.

What is the septum?

A wall separating the left and right sides of the heart.

What supplies the heart muscle with blood?

Coronary arteries.

What does ECG stand for?

Electrocardiogram.

How is heart rate measured?

In beats per minute.

What happens to heart rate during exercise?

It increases.

What is coronary heart disease?

Blockage of coronary arteries by fatty deposits.

What causes angina?

Partial blockage of coronary arteries.

What causes a heart attack?

Complete blockage of a coronary artery.

How can CHD risk be reduced?

Exercise healthy diet stop smoking.

What is the function of valves in the heart?

Prevent backflow of blood.

What valve separates right atrium and ventricle?

Tricuspid valve.

What valve separates left atrium and ventricle?

Bicuspid valve.

What are semilunar valves?

Valves preventing blood flowing back into the heart from arteries.

What is the function of arteries?

Carry blood away from the heart at high pressure.

What is the function of veins?

Carry blood towards the heart at low pressure.

Why do veins have valves?

To prevent backflow of blood.

What are capillaries?

Tiny vessels allowing exchange of substances with cells.

Why are capillary walls one cell thick?

To allow fast diffusion.

What is plasma?

Liquid part of blood transporting substances.

What do red blood cells transport?

Oxygen.

Why do red blood cells have no nucleus?

To carry more haemoglobin.

What do white blood cells do?

Defend against pathogens.

What are platelets responsible for?

Blood clotting.

What is phagocytosis?

Engulfing and digesting pathogens.

What do lymphocytes produce?

Antibodies and antitoxins.

What is fibrinogen converted into during clotting?

Fibrin.

What forms a blood clot?

A mesh of fibrin trapping red blood cells.