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Flashcards in Biology a Deck (110)
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What is osmosis ?

The movement of water molecules across a partially permeable membrane from a region I high concentration to low concentration


What is a partially permeable membrane ?

A membrane with very small holes in, only small molecules can pass through them


How does water move in and out of cells ?

Through osmosis. Human cells have a semi permeable membrane - cell membrane


What is tissue fluid ?

It is what surrounds the cells in the body, it supplies the cells with everything it needs - water, oxygen, glucose, etc.


What three ways can substances move ?

Active transport


What is an exchange surface ?

It is what substances have to pass through, in osmosis, diffusion and active transport, in life processes. Like partially permeable membranes


How are exchange surfaces adapted for maximum effectiveness ?

•They are thin so the substance only has to pass a short distance
•Large surface area so more substances can pass through
•Good blood supply


What has the structure of a leaf adapted to do ?

Let gases diffuse in and out of cells


How has a leaf adapted to optimise gas and liquid exchange ?

•It has air gaps so carbon dioxide can diffuse into cells
•Underside of leaf covered with stomata
•Water vapour and oxygen diffuse out through stomata
•Flat shape of leaf increases area of exchange


How do guard cells affect stomata ?

They control stomata. They close if the stomata is losing too much water. Without guard cells the plant would wilt.


What is the thorax ?

The top part of your body


What separates the thorax from the abdomen (lower body) ?

The Diaphragm


How does the air you breath get into your lungs ?

It goes down the TRACHEA and is split into two tubes called BRONCHI. Each BRONCHUS progressively becomes smaller into tubes called BRONCHIOLES. They take the air to ALVEOLI where the gas exchange takes place.


What is ventilation ?

The movement of air in and out of the lungs


What are the intercostal muscles ?

Muscles between ribs


How do you breath in ?

As air goes in, intercostal muscles and the diaphragm contract. The thorax volume increases which lowers pressure in the lungs which draws the air in.


How do you breathe out ?

The intercostal muscles and the diaphragm relax which increases the pressure in the lungs which forces air out.


What do artificial ventilators do ?

They help people to breathe


What are villi ?

They are projections that line the surface of the small intestine. The increase surface area to absorb as much food as possible into the blood.


How are alveoli specialised to maximise diffusion ?

•A large surface area
•A moist lining for dissolving gases
•Very thin walls
•Good blood supply


What is the job of the lungs ?

To transfer oxygen into the blood and to remove waste carbon dioxide from it. They have millions of alveoli which are like little air sacks where gas exchange takes place.


What are cells on the surface of a plant's root called and what do they do ?

Root hair cell. It sticks out into the soil which increases it's surface area. As a result they are great at absorbing water and minerals


How are minerals taken in to the root hair cells ?

Through active transport


When does active transport take place ?

When the concentration of a substance in the area you want the substance to go to is high, diffusion cannot take place. This is when active transport is needed


What does active transport need for it to happen ?



Where does active transport take place in the human body ?

One example is When glucose is taken from the gut into the blood


What does phloem transport ?



How do phloems work ?

They transport food substances from the leaves to growing regions like shoots. They do this by allowing the dissolved sugars to pass through small holes in the end


What do the xylem tubes transport ?

They transport water and minerals from the roots to the stem and leaves.


What are xylem constructed out of ?

Dead cells joined end to end