AQA GCSE Biology B1 Cell biology and B2 Organisation

B1 Name part of a eukaryotic cell that is not found in a bacterial cell?

The nucleus, mitochondria

B1 Diffusion is .....

where particles spread out from an area of higher concentration to an area of lower concentration.

B1 What is the function of chloroplasts?

chloroplasts absorb light energy to make glucose (in photosynthesis)

B1 If the concentration of the solution inside a cell is lower than outside the cell, what will the net movement of water molecules be?

(It moves by osmosis) from inside (more dilute) to outside (more concentrated) the cell

B1 When using a light microscope to view a slide, which lens should be selected to start with? Suggest the total magnification with this lens.

The lowest-powered lens. If it is the x4 objective, the total magnification will be x40 (if the eyepiece is x10, objective x4)

B1 What is mitosis?

Mitosis is cell division in eukaryotes that produces two genetically-identical cells

B1 What is a stem cell?

A stem cell is an undifferentiated cell which can give rise to more cells of the same type, and can differentiate into a range of specialsed cells

B1 What is the role of mitochondria?

Mitochondria are the site of aerobic respiration

B1 What is the role of the nucleus?

Nucleus contains the genetic material with instructions for building proteins that determine the activity of the cell

B1 Describe the exchange of gases when air is breathed into the lungs

Oxygen diffuses into the blood from the lungs and carbon dioxide diffuses out of the blood into the air in lungs

B1 In a plant cell, what is the vacuole?

A space inside a plant cell which is filled with cell sap

B1 What are the characteristics that make the alveoli efficient at gas exchange?

Alveoli have thin walls/one cell thick (for a short diffusion path); they have a large surface area

B1 Discs containing different antiseptic solutions are placed on an agar plate covered in bacteria. After several days, how could you compare the effectiveness of each antiseptic?

Measure the diameter of the zone of inhibition (the clear zone) around each disc. The larger the diameter, the more effective the antiseptic

B1 What happens inside a cell before mitosis takes place?

The number of subcellular structures in the cell increases; the DNA is replicated

B1 Describe one disadvantage of using embryonic stem cells in medicine?

there is a risk of the stem cells being infected with viruses and these being passed on to patients; a risk of cancer (embryonic stem cells divide rapidly); some people feel that human embryos shouldn't be used to create stem cells as each one is a potential human life; embryo's cannot give consent; it is an expensive treatment in a health system with limited resources.

B1 Electron microscopes have a higher resolution than light microscopes. Give one reason why this is beneficial when viewing cells with an electron microscope.

Subcellular structures can be studied in more detail

B1 Explain one way in which a nerve cell is adapted to carry out its specialised function.

Nerve cells are for communication, so one of the following: they are long/have long axons; are adapted to carry electrical signals/have insulating sheath; have branched ends to connect with other cells

B1 Explain why root hair cells in plants might use active transport.

To obtain minerals (e.g. nitrates) from the soil against their concentration gradient (because they need them for healthy growth)

B2 What is a tissue?

A collection of similar cells that carry out a particular function

B2 What colour change does iodine solution go through in the presence of starch?

From browny-orange to blue-black

B2 Where is bile produced and stored?

Bile is produced in the liver and stored in the gall bladder.

B2 How are arteries adapted to their function?

They have thick and elastic walls to withstand high pressure

B2 How are veins adapted to their function?

Then have valves to prevent backflow

B2 How are capillaries adapted to their function?

They have thin walls (for a short diffusion path in the exchange of substances)

B2 What is the function of the coronary arteries?

To supply blood to the heart muscle

B2 Name the chamber of the heart that receives blood from the vena cava

right atrium receives blood from vena cava

B2 Name the vessel that carries blood away from the left ventricle

aorta carries blood away from left ventricle

B2 What's the function of palisade mesophyll tissue?

Palisade mesophyll tissue is the main site of photosynthesis

B2 What is the role of protease enzymes?

Protease enzymes catalyse the breakdown of proteins into amino acids

B2 Describe the function of phloem tissue

Phloem tissue transports (dissolved) sugars from source (leaves) to sink (where sugars are used). This is called translocation.

B2 Give two substances that are carried around the body dissolved in the blood plasma

carbon dioxide, amino acids, salts, urea, glucose, oxygen

B2 Describe what happens to an enzyme if the temperature is too high (3 marks)

bonds in the active site are broken; so the shape of the active site doesn't match the substrate; so it becomes denatured

B2 Describe the path of air as it moves from the mouth into the lungs to exchange gases with the blood (use the names of parts of the lung)

From trachea to bronchi (and bronchioles) and then alveoli

B2 What is the three functions of white blood cells?

White blood cells: engulf pathogens; produce antitoxins; produce antibodies

B2 Why is the shape of the active site of an enzyme important for its function?

The shape of the active site is important because it matches the shape of the substrate in the reaction the enzyme is catalysing

B2 What is the name of the cells that control the opening and closing of stomata?

Guard cells

B2 What is the function of amylase enzyme?

Amylase breaks down starch to sugar

B2 Give one advantage of using an artificial heart rather than transplanting a natural one

artificial hearts are made from materials that are less likely to be rejected by the immune system

B2 What is a benign tumour?

A mass of abnormal cells that doesn't spread to other tissues of the body

B2 Explain how increasing air movement around a plant's leaves would affect the rate of transpiration

Increasing air movement increases the rate of transpiration because water vapour is moved away from the leaf so the concentration gradient of water vapour between the inside and outside of leaf would increase, so more diffusion would occur

B2 What is the role of digestive enzymes?

digestive enzymes catalyse the breakdown of food into small, soluble molecules that can diffuse into the blood

B2 How can you test for the presence of protein?

Biuret solution goes from blue to lilac in the presence of protein

B2 Name two places that produce amylase

the salivary glands and the pancreas produce amylase

B2 What is the role of xylem tissue?

To transport water and dissolves minerals from the roots up the stem to the leaves

B2 What artificial device can be used to keep arteries open and blood flowing?

A stent

B2 What substance, produced during photosynthesis, diffuses out of a plant via the stomata?

Carbon dioxide

B2 Which word describes the loss of water from a plant's surface?

Transpiration

B2 Explain how statins can reduce a person's risk of coronary heart disease

Statins reduce the amount of fatty deposits that will accumulate on the walls of coronary arteries (by reducing the amount of 'bad' cholesterol in the blood)

B2 The heart contains cells that act as a pacemaker. Where are these cells located in the heart?

Pacemaker cells are in the right atrium