Cells and Biological Molecules

Question 1

Define tissue

Answer 1

A group of cells working together to carry out a specific function.

Question 2

Define organ

Answer 2

A group of tissues working together to carry out a specific function.

Question 3

Define organ system

Answer 3

A group of organs working together to carry out a specific function.

Question 4

How is the labour divided within a cell?

Answer 4

Within a cell, labour is divided between the organelles

Question 5

Name 5 parts of an animal cell

Answer 5

• Nucleus
• Mitochondria
• Ribosomes
• Cell membrane
• Cytoplasm

Question 6

Name 8 parts of a plant cell

Answer 6

• Nucleus,
• mitochondria,
• ribosomes,
• cell membrane,
• cytoplasm,
• permanent vacuole,
• chloroplasts,
• cell wall

Question 7

State 2 functions of the nucleus

Answer 7

• Controls the cell
• Contains genetic material (in the form of chromosomes)

Question 8

What is the function of the cytoplasm?

Answer 8

It is where most of the cell’s chemical reactions take place.

Question 9

State the function of mitochondria

Answer 9

They are the site of aerobic respiration.

Question 10

State the function of ribosomes

Answer 10

They are the site of protein synthesis.

Question 11

What is the function of the cell wall and what is it made of?

Answer 11

It provides strength and support. It is made of cellulose.

Question 12

What is the function of the permanent vacuole and what does it contain?

Answer 12

It supports the cell and contains cell sap (a solution of sugars and salts).

Question 13

What is the function of chloroplasts?

Answer 13

They are the site of photosynthesis.

Question 14

What is the function of the cell membrane?

Answer 14

• Controls what enters and leaves the cell
• Separates the cell from its environment

Question 15

What is differentiation?

Answer 15

The process by which cells become specialised

Question 16

What are stem cells?

Answer 16

Stem cells are unspecialised cells that can differentiate into lots of different types of cells.

Question 17

Give 3 advantages of using stem cells in medicine

Answer 17

• Stem cells can be used to treat paralysis
• Stem cells have the possibility to cure degenerative diseases like Parkinson’s
• Whole new tissues or organs can be grown that can be used to test drugs on

Question 18

Give 3 disadvantages of using stem cells in medicine

Answer 18

• Using embryonic stem cells can raise ethical issues
• It is expensive
• Long term side effects are unknown

Question 19

What chemical elements are present in carbohydrates?

Answer 19

Carbon, hydrogen, oxygen (C,H,O).

Question 20

What chemical elements are present in lipids?

Answer 20

Carbon, hydrogen and oxygen (C,H,O).

Question 21

What chemical elements are present in proteins?

Answer 21

Carbon, hydrogen, oxygen, nitrogen and sulfur (C,H,O,N,S).

Question 22

What are complex carbohydrates like starch and glycogen made up of?

Answer 22

Simple sugars

Question 23

What are proteins made up of?

Answer 23

Proteins are made up of amino acids.

Question 24

What two molecules are lipids made up of?

Answer 24

Glycerol and fatty acid tails

Question 25

What are enzymes?

Answer 25

Enzymes are biological catalysts that increase the rate of metabolic reactions.

Question 26

State 4 factors that affect enzyme function

Answer 26

• Temperature
• pH
• Substrate concentration
• Enzyme concentration

Question 27

Describe the effect of temperature on the rate of an enzyme-controlled reaction

Answer 27

• As the temperature increases, so does the rate of reaction
• Once the temperature exceeds the optimum, the enzyme denatures and the rate of reaction decreases

Question 28

Why does the rate of an enzyme-controlled reaction increase when the temperature increases?

Answer 28

• As the temperature increases the particles have more kinetic energy
• This increases the chance of collisions between molecules being successful and leading to a reaction

Question 29

If temperature increases above the optimum, how does this affect enzyme function?

Answer 29

The active site will be distorted as the enzyme denatures and so it will no longer fit the substrate

Question 30

Describe the effect of pH on the rate of an enzyme-controlled reaction

Answer 30

• The rate of an enzyme catalysed reaction is fastest at the optimum pH
• If the pH is too high or low, the enzyme will work less efficiently and the active site may be denatured at extremes of pH

Question 31

Define diffusion

Answer 31

The net movement of molecules from an area of high concentration to an area of low concentration down their concentration gradient.

Question 32

How does temperature affect the rate of diffusion?

Answer 32

As the temperature increases, so does the rate of diffusion as the particles have more kinetic energy and move faster.

Question 33

How does the concentration gradient affect the rate of diffusion?

Answer 33

The greater the concentration gradient (the difference between the two areas), the faster the rate of diffusion.

Question 34

How does the surface area of the membrane affect the rate of diffusion?

Answer 34

As the surface area increases so does the rate of diffusion as there is more space for the particles to move through.

Question 35

Define osmosis

Answer 35

The net movement of water molecules from a high water potential to a low water potential down their water potential gradient across a partially permeable membrane

Question 36

Define active transport

Answer 36

The movement of molecules from a low concentration to a high concentration against their concentration gradient using energy.