B4 - Organising Animals and Plants

Question 1

Components of blood

Answer 1

Plasma - 55%
White BCs and platelets - <1%
Red BCs - 45%

Question 2

Components and functions of RBCs

Answer 2

Biconcave discs - maximises surface area for diffusion of oxygen.
Haemoglobin - Red pigment that binds to oxygen.
No nucleus - More space for haemoglobin and therefore haemoglobin.

Question 3

Components and functions of WBCs

Answer 3

Lymphocytes - generate antibodies to neutralise pathogens with antigens. Some produce antitoxins to neutralise the toxins generated by pathogens
Phagocytes - these cells engulf and digest bacteria.

Question 4

Components and functions of platelets

Answer 4

Small fragments of cells
No nucleus
Allow blood to clot at wound site.

Question 5

What are the different blood vessels?

Answer 5

Arteries
Veins
Capillaries

Question 6

Features of an artery

Answer 6

Small lumen
High pressure
Carry blood away from heart
Thick walls
Thick layer of muscle and elastic fibres

Question 7

Features of an vein

Answer 7

Large lumen
Carries blood towards heart
Has valves to prevent backflow
Blood flow can be assisted with skeletal muscles.
Relatively thin walls

Question 8

Features of an capillary

Answer 8

Walls one cell thick
Very narrow lumen
Thinness allows oxygen and glucose to diffuse into bloodstream easily.

Question 9

What is the double circulatory system?

Answer 9

One transport system carries blood from the heart to your lungs and back. Allows for oxygenation of the blood.
Another transport system carries blood to all the parts of the body that require it.

Question 10

What are the benefits of the double circulatory system?

Answer 10

Efficiency - blood can be transported around the body constantly at high pressure.

Question 11

Revise heart diagram

Answer 11

Revise heart diagram

Question 12

Heart problems

Answer 12

Coronary arteries become clogged with fat deposits, reducing the supply of oxygen - this can result pain, cardiac arrest and death.

Question 13

Solutions to heart problems

Answer 13

Stent - a metal mesh or wire led up an artery in the leg to the coronary artery. When in place, a balloon inside of it inflates and causes the wire to expand , opening the artery.
Bypass surgery - use a vein from another part of the body instead. Expensive and risk of general anaesthetic.
Statins - Drugs to reduce cholesterol levels and therefore slows down rate at which fatty deposits are created.

Question 14

Helping the heart

Answer 14

Leaky valves made out of titanium and polymers. Only last 12-15 years.
Artificial pacemakers - sends strong electrical signals to the heart by two wires, stimulating it to beat properly.
Artificial heart - can be used to give diseased hearts a rest. Only last a short time - expensive and complex.

Question 15

How does the gas exchange system work?

Answer 15

Oxygen rich air moves into your lungs. This allows for a steep concentration with the blood. Therefore, the oxygen diffuses up the gradient and into the bloodstream through the alveoli. Carbon dioxide diffuses out and oxygen in.

Question 16

Adaptations of alveoli

Answer 16

Very thin alveolus walls make diffusion easy for oxygen.

Spherical shape of alveolus increases surface area for diffusion.

Question 17

Plant tissues

Answer 17

Epidermal tissues - cover the surface of the leaf. Often secrete waxy substance for waterproofing.
Palisade mesophyll - contains majority of chloroplasts, allowing for photosynthesis to occur and a green colour.
Spongy mesophyll - contains some chloroplasts but has big air spaces and a large surface area, increasing rate of diffusion for gases.

Question 18

Transport tissues

Answer 18

Xylem - transports water and soluble minerals up the plant.

Phloem - carries food like glucose from the leaves around the plant. This is called translocation.

Question 19

Water loss through leaves

Answer 19

Water is lost through leaves through stomata, which open to release oxygen through the plant. However, plants also lose water vapour when these are opened. This is called transpiration. Anything that affects rate of evaporation also affects rate of transpiration.

Question 20

Factors affecting transpiration

Answer 20

Wind - makes water evaporate faster, making the concentration gradient steeper.
Light - photosynthesis increased, so stomata open more often, transpiring more water.
Humidity - makes concentration gradient milder, causing less water to escape from the plant.
Heat - Kinetic energy of water molecules increases, increasing diffusion.

Question 21

Why is a potometer not 100% accurate

Answer 21

Some water will go to metabolic reactions within the plant, and so will not be transpired.