B2.1

Question 1

What is diffusion?

Answer 1

The net movement of particles down a concentration gradient (high to low concentration)
Passive process

Question 2

In the body, name 2 uses of diffusion

Answer 2

Oxygen and glucose into cells, carbon dioxide out of cells

Question 3

How do you increase the rate of diffusion?

Answer 3

Decrease the distance needed to move
Increase the surface area
Increase the concentration gradient

Question 4

What is osmosis

Answer 4

The diffusion of water particles across a partially permeable membrane from a high water potential to low water potential
Passive process

Question 5

How is water potential determined?

Answer 5

By the concentration of free water molecules

Pure water has the highest water potential,and the more concentrated a solution is the lower the water potential

Question 6

Why is osmosis not always a good thing?

Answer 6

It can lead to animal and plant cells becoming burst or crinkled

Question 7

Match the word to the cell and cause
Crenated
Plasmolysed
Turgid
Lysis

Answer 7

Crenated - crinkled animal cell, as it loses water
Plasmolysed - softened and collapsed plant cell, as it loses water
Turgid - firm and rigid plant cell, as it gains water
Lysis - burst animal cell,as it gains water

Question 8

What is active transport?

Answer 8

The process which allows cells to move substances against the concentration gradient
Active process

Question 9

Why would you expect root hair cells to have lots of mitochondria?

Answer 9

They absorb mineral ions by active transport. As it is against the concentration gradient, ATP (from respiration) is required. Mitochondria are needed for respiration

Question 10

What does the ATP in active transport do?

Answer 10

Allow Carrier proteins in the cell membrane to transport substances i.e by flipping over

Question 11

What are 3 examples of active transport

Answer 11

Plants taking mineral ions from the soil
Nerve cells taking in potassium ions and sodium ions leaving
Glucose being transported to the bloodstream through the villi

Question 12

What is mitosis?

Answer 12

The process in which body cells divide and duplicate

Question 13

How can you tell if DNA is being replicated for mitosis, not for transcription

Answer 13

If it is for mitosis, there will be no uracil

Question 14

How do chromosomes move in mitosis?

Answer 14

After being copied, they line up at the centre
Spindle fibres pull them to opposite ends of the cell
2 nuclei form

Question 15

What happens after the movement of chromosomes in mitosis?

Answer 15

Cytokinesis - The membrane pinches off to separate the 2 nuclei and creates 2 cells

Question 16

What is the ‘transition’ stage between mitosis that allows it to be called a cell cycle

Answer 16

The growth of daughter cells

Question 17

What is cell differentiation

Answer 17

When cells become specialised to perform a particular job

Question 18

Name and explain the adaptations of some specialised cells in animals

Answer 18

Sperm cells - tail,lots of mitochondria,acrosome to break layers of ovum and transfer genetics

Fat cells - A layer of cytoplasm with fat inside, can expand to x1000 size

Ciliated cells - In airways, goblet cells provide mucus to trap bacteria, cilia sweep them away.

Red blood cell - biconcave,haemoglobin,no nucleus, can easily pass through capillaries

Question 19

Name and explain the adaptations of a specialised plant cell

Answer 19

Palisade cells - Regular shape for close packing,close to surface of leaf,chloroplasts

Question 20

What is a stem cell?

Answer 20

Undifferentiated cells which can divide by mitosis, and those cells can differentiate and become specialised

Question 21

State 2 differences between embyronic and adult cells

Answer 21

Adult cells are used for repair, embryonic for growth

Embryonic can differentiate into all cell types, adult can only differentiate into a limited range of cells

Question 22

Referring to stem cells, how are humans born?

Answer 22

After the sperm fertilises the egg, a zygote (stem cell) is produced,and it divides and produces all the cells needed to make a person

Question 23

Where are stem cells found in plants?

Answer 23

Meristems, for example shoot tips

Meristems are the only parts where a plant grows