B1: Cell Structure

Question 1

What is magnification?

Answer 1

How many times larger the image is than the object.

Question 2

What is the equation for magnification?

Answer 2

Image size / object size

Question 3

What is resolution?

Answer 3

The shortest distance between two points on an object that can still be distinguished at two separate entities

Question 4

What is the pathway of light through a microscope?

Answer 4

Light source, stage, microscope slide, object, objective lens, body tube, eyepiece lens, eye

Question 5

What are advantages of light microscopes?

Answer 5

Easy to use and relatively cheap

Question 6

What is a disadvantage of light microscopes?

Answer 6

Low resolution

Question 7

What are disadvantages of electron microscopes?

Answer 7

Very expensive and hard to use

Question 8

What are advantages of electron microscopes

Answer 8

Have a high resolution

Question 9

What is the function of the cell wall?

Answer 9

The cell wall is made of cellulose, and this helps to strengthen the cell

Question 10

How are nerve cells specialised for their functions?

Answer 10

They have dendrites, which make connections with other cells, an axon, which carries nerve impulse from one place to another and synapses, which pass impulses from one place to another

Question 11

How are muscle cells specialised for their functions?

Answer 11

Contain special proteins that slide over each other, many mitochondria to transfer energy needed for chemical reactions and can store glycogen

Question 12

How are sperm cells specialised for their functions?

Answer 12

Long tail to help sperm move, many mitochondria for tail to move and the acrosome which stores enzymes to break through egg’s outer layer

Question 13

How are root hair cells specialised for their functions?

Answer 13

Have a high surface area for water to move into the cell, permanent vacuole to speed movement of water by osmosis and mitochondria to carry out active transport

Question 14

How is the xylem specialised for its functions?

Answer 14

Dead cells which form hollow tubes for water and minerals to pass. Lignin makes the cell walls strong, helping them withstand pressure

Question 15

How is the phloem specialised for its functions?

Answer 15

Sieve plates allow water carrying dissolved food to move up tubes. Companion cells keep them alive and contain mitochondria for energy to move dissolved food

Question 16

What is diffusion?

Answer 16

The net movement of particles from an area of high concentration to an area of low concentration

Question 17

Give examples of when diffusion occurs

Answer 17

Oxygen and carbon dioxide in gas exchange and the waste product of urea from cells into the blood plasma for excretion in kidneys

Question 18

What 3 factors affect the rate of diffusion?

Answer 18

Concentration gradient, temperature and surface area of membrane

Question 19

What 4 factors increase the effectiveness of exchange surfaces?

Answer 19

A large surface area, thin membrane, which provides a short diffusion distance, having an efficient blood supply and being ventilated

Question 20

What is osmosis?

Answer 20

The net movement of water molecules from a dilute solution to a concentrated solution through a semi-permeable membrane

Question 21

What is osmosis?

Answer 21

The net movement of water molecules from a dilute solution to a concentrated solution through a semi-permeable membrane

Question 22

What is active transport?

Answer 22

The net movement of particles from an area of low concentration to an area of high concentration (against the concentration gradient) requiring energy

Question 23

Which molecules are able to diffuse into and out of cells? Why?

Answer 23

Amino acids, water and glucose because they are small molecules

Question 24

True or false: Active transport can only take place across a membrane

Answer 24

True

Question 25

How are the lungs and intestines adapted to increase surface area?

Answer 25

Lungs have millions of alveoli and intestines have villi

Question 26

Give examples of exchange systems

Answer 26

Gills in fish and the leaves in root hair cells

Question 27

What are 4 general features that exchange surfaces have in common?

Answer 27

Large surface area so more particles can pass at once. Thin membranes, reduce distance and membranes are ventilated as well as a diffusion gradient

Question 28

Explain 3 ways alveoli make good exchange surfaces

Answer 28

Lots of alveoli, increasing the surface area which allows more molecules to diffuse across in a given time, substances are thin, which decrease diffusion distance and a good blood supply, which maintains a strong concentration gradient as blood is constantly replaced

Question 29

Which adaptation in plants contributes to the efficient exchange of gases?

Answer 29

The flattened shape of leaves