Structures and Functions in Living Organisms

Question 1

What are the levels of organisation?

Answer 1

Organelles-> Cells-> Tissues-> Organs-> Systems

Question 2

What does a nucleus do ?

Answer 2

Controls the activity of the cell and contains genetic materials.

Question 3

What happens in a cytoplasm ?

Answer 3

Where all the cell’s reactions take place

Question 4

What does a cell membrane do ?

Answer 4

Holds the cell together and controls what goes in and out.

Question 5

What does a mitochondria do ?

Answer 5

Generates energy in the form of ATP

Question 6

What three organelles do plants have that plants don’t and what are their functions

Answer 6

Cell wall- made of cellulose, gives support to cell (no skeletons)
Vacuole- contains cell sap, weak solution of sugars and salts.
Chloroplasts- contains chlorophyll needed for photosynthesis.

Question 7

What are carbohydrates made of

Answer 7

Carbon
Hydrogen
Oxygen

Question 8

Monosaccharides

Answer 8

e.g. Glucose/fructose

simple one unit sugars that taste sweet when dissolved in water.

Question 9

Disaccharides

Answer 9

E.g. Maltose, lactose and sucrose
Dissolve in water
Maltose= glucose + glucose

Question 10

Polysaccharide

Answer 10

E.g. Starch or cellulose in plants
Glycogen= animals

Complexed molecules used for storage
Don’t break up easily
Don’t easily dissolve in water

Question 11

Sources and function of carbs

Answer 11

Cereals, rice, wheat, barley, maize, fruits and veg.

Main source of energy and also stores energy.
Used for structures in plants.

Question 12

What are lipids made of

Answer 12

Carbon hydrogen and oxygen

3 fatty acids and 1 glycerol

Question 13

What enzyme breaks down starch

Answer 13

Amylase

Starch –> maltose

Question 14

Sources of lipids

Answer 14

Cheese, milk, eggs nuts and seeds

Question 15

Functions of lipids

Answer 15

Provides energy
Insulates important organs
Forms parts of the cell membrane
Uses cholesterol to make steroid hormones

Question 16

What enzyme breaks down lipids

Answer 16

Lipase

Lipids–> fatty acids and glycerol

Question 17

What are proteins made up of

Answer 17

Carbon, hydrogen, nitrogen, oxygen (+ sulphur)

Long and thin= keratin.
Spherical= haemoglobin

Question 18

What are sources of proteins

Answer 18

Meat, fish, eggs, nuts and seeds

Question 19

What is the function of protein ?

Answer 19

Growth and repair of muscles
Catalysts
Hormones
Antibodies

Question 20

What enzyme breaks down protein

Answer 20

Protease

Protein–> amino acids and peptides

Question 21

How do you test for glucose

Answer 21

Liquefy food sample
Dissolve in Benedict’s solution
Heat in water bath
Glucose= brick orange ppt

Question 22

Test for starch

Answer 22

Liquefy food sample
Add iodine solution
Yellow= no starch
Blue/black= starch

Question 23

What are enzymes

Answer 23

Biological catalysts that catalyse many different metabolic reactions. They are specific.

They speed up reactions but remain chemically unchanged.

Question 24

What is the optimum temperature for enzymes in humans

Answer 24

37 degrees Celsius

Question 25

What are enzymes sensitive to

Answer 25

Heat and ph.
Temp too high, then the enzyme will be denatured= active site shape changes so the substrate is no longer complementary to the active site.

Ph too high= bonds holding enzymes structure are broken..denatured.

Question 26

What is diffusion

Answer 26

The net movement of particles from areas of higher concentration to areas of lower concentration until a uniform composition is achieved.

Question 27

What is osmosis

Answer 27

The net movement of water molecules for, areas of high water molecule conc. To lower water molecule conc. Across a partially permeable membrane.

Question 28

What is active transport

Answer 28

The transport of dissolved molecules against the concentration gradient by using energy in the form of ATP.

Question 29

Why can plants be turgid or flaccid?

Answer 29

Osmosis.
If water enters, volume of cytoplasm increases, exerting pressure outwards. This means that the cell is stronger and has support to grow upwards.

Question 30

What factors affect the rate of substances going in and out and why?

Answer 30

SA: a large surface area means that molecules have more space to diffuse through, increasing the rate of movement.

Temp: the higher the temp, the higher the KE there is, making more molecules collide with the cell membrane= movement more likely.

Conc. Grad: the bigger the different in conc. Gradient, the re opportunities particles have to diffuse= quicker.

Question 31

Diffusion experiment

Answer 31

Put a coloured substance in water
Time how long it takes for a uniform composition
Repeat experiments at different temperatures= compare times

• higher temp= higher KE= more collisions = substance moves through liquid quicker

Question 32

Osmosis experiment

Answer 32

Cut two potato cylinders of the same size.
Put on in water and one in salt water

Salt water= potato loses mass as water diffuses out by osmosis to area of lower water molecule conc.
Water= potato gains mass as water diffuses in by is moms to area of Lower water molecule conc.