B3 Revision Answers

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  • Created by: Issynx
  • Created on: 22-03-16 18:41

1: Movement of Molecules

How do dissolved substances move?
Diffusion and active transport

What is osmosis?
Diffusion of water from a dilute solution to a more concentrated solution through a partially permeable membrane.

What does the PPM do?
Allows water molecules through and stops solute molecules because they are too large

What is active transport?
Where substances are absorbed against a concentration gradient

What does this require and allow?
Energy from respiration/Allows cells to absorb sugar and ions

How do plants and humans use this?
Plants absorb ions from very dilute solutions in soil and in humans, sugar can be absorbed from the intestines and kidney tubules

Why do sports drinks contain water, sugar and ions?
To replace sugar used to release energy and to replace water and ions lost through sweating

Name 4 things that make exchange surfaces efficient
Large surface area, thin (short diffusion path), efficient blood supply and being ventilated for gas exchange

What do villi and alveoli do to maximise effectiveness?
Villi increase SA of the small intestine and alveoli increase SA of lungs

Where is the breathing system located, what does it involve and what is it protected by?
Located in the thorax, involves lungs and is protected by ribcage

How are the thorax and abdomen divided?
By a muscular sheet called the diaphragm

What does the breathing system do?
Take air in and out of the body so oxygen can be diffused into the blood and carbon dioxide can be diffused out of the blood

Describe a picture of the lungs
The air reaches your lungs via the trachea which then divides into 2 tubes called the bronchi. Then the bronchi divides into bronchioles until they end at air sacks called alveoli

Why are alveoli efficient at exchanging oxygen and carbon dioxide?
They are close to blood capillaries, large moist surface area and excellent blood supply

What is ventilation?
The movement of air, in and out of your lungs

What happens when you breathe in?
Your ribcage moves up and out and the diaphragm contracts to let more air in

What happens when you breathe out?
Your ribcage moves in and down and the diaphragm relaxes

What does a ventilator do?
Improve gas exchange in the body

What do root hairs do?
Provide a large surface area in the roots

How are leaves adapted?
Broad, thin and flat with lots of internal air spaces to provide a large surface area

During photosynthesis what do stomata do?
Let carbon dioxide in and let oxygen out

What is the movement of water through a plant called?

When is evaporation most rapid?
In hot, dry and windy conditions

2: Transport Systems


What does the circulatory system do and what does it consist of?
Transports substances around the body and consists of heart, blood vessels and blood

What does oxygenated blood do?
Provides glucose and oxygen to cells

What does deoxygenated blood do?
Takes away waste products

Name the 9 main parts of the heart


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