B2.1

Question 1

Diffusion

Answer 1

The overall movement of particles from a region of high concentration to a region of low concentration

Question 2

Factor that affects the rate of diffusion: decreasing the distance the particles need to move

Answer 2

Takes less time to travel a shorter distance

Question 3

Factor that affects the rate of diffusion: increasing the concentration gradient

Answer 3

The steeper the concentration gradient, the greater the net movement of particles

Question 4

Factor that affects the rate of diffusion: increasing surface area

Answer 4

Allows more space for diffusion, so more particles can move in a period of time

Question 5

Osmosis

Answer 5

A type of diffusion where the water molecules from a high water potential move to a region of low water potential

Question 6

Water potential

Answer 6

The concentration of free water molecules

Question 7

Turgid

Answer 7

Firm

A cell becomes turgid when the concentration of a solution outside it decreases (higher water potential). In this situation it may burst, known as lysis

Question 8

Flaccid

Answer 8

Soft

A cell becomes flaccid when the concentration of the surrounding solution increases (lower water potential). In this situation the cell may collapse and crinkle. This is known as being crenated

Question 9

Active transport

Answer 9

Allows cells to move substances from an area of low concentration to an area of high concentration

As the particles are going against their concentration gradient, energy is required

Question 10

Key features of Active Transport

Answer 10

Particles are transported against their concentration gradient

ATP (energy) is required

Carrier proteins in the cell membrane bind to the substance and rotate, transporting it into the cell

Question 11

Example of active transport

Answer 11

Digestion

Small intestines, carbs are broken down into glucose

Glucose is actively transported by the villi into the bloodstream

Question 12

Mitosis

Answer 12

The process by which body cells divide

Question 13

Cell cycle

Answer 13

The process of cell growth and division

Question 14

First Stage of the Cell Cycle

Answer 14

Transcription

Question 15

Second Stage of the Cell Cycle

Answer 15

Movement of chromosomes

The chromosomes line up across the centre of the cell

The two identical copies of each chromosome, formed when the DNA replicated, separate and move to opposite ends of the cell

Each end now contains a full set of identical chromosomes

Two new nuclei then form

Question 16

Cell Differentiation

Answer 16

When a cell becomes specialised to perform a particular job

It’s structure changes so it’s better adapted to perform its function

This makes the entire organism more efficient, as life process are carried out more effectively

Question 17

Sperm Cell adaptations

Answer 17

Flagellum - propels the sperm to the ovum

Lots of mitochondria - allows the flagellum to move rapidly

Acrosome - stores digestive enzymes which break down the outer layer of the ovum

Question 18

Fat Cell adaptations

Answer 18

Small layer of cytoplasm surrounding a fat reservoir

They can expand up to 1000 times their original size as they fill with fat

Question 19

Red Blood cell

Answer 19

Biconcave disks - increases surface area

Full of haemoglobin - binds to oxygen to form oxyhemoglobin

Non nucleus - saves space

Question 20

Stem cell

Answer 20

An undifferentiated cell

Question 21

Embryonic stem cell

Answer 21

Found in embryos

Can differentiate into all cell types

Question 22

Adult stem cell

Answer 22

Found in various body tissues such as the brain, bone marrow, skin, and liver

Can differentiate into some cell types

Act as a repair mechanism for the body

Question 23

Meristems

Answer 23

Stem cells in plants are found here

They have a small size, very thin walls, small vacuoles, and no chloroplast

Differentiated cell’s cannot divide as their cell walls are thick and rigid