Year 10 Chapters 1-3

Question 1

What is diffusion?

Answer 1

The net random movement of particles from an area of high concentration to low concentration. No energy is required to move

Question 2

What effects the rate of diffusion?

Answer 2

• Concentration gradient: the higher the concentration on one side compared to the other the faster the rate of reaction.
• Temperature: the molecules gain kinetic energy therefore the net random movement increases increasing the rate of reaction.

Question 3

What is osmosis?

Answer 3

It is the movement of water molecules from an area of high water potential to an area of low water potential, it must be across a partial permeable membrane, e.g. a cell membrane.

Question 4

What is a hypertonic solution?

Answer 4

If the solution outside the cell has a higher concentration than inside the cell.

Question 5

What is a hypotonic solution?

Answer 5

If the solution outside the cell has a lower concentration than inside

Question 6

What is an isotonic solution?

Answer 6

If the solution outside the cell has the same concentration as inside

Question 7

What is a eukaryotic cell?

Answer 7

A multicellular organism which contains a cell membrane, cytoplasm and genetic material in strings of chromosomes which is enclosed in the nucleus. Animal and plant cells are examples of eukaryotic cells.

Question 8

What is a prokaryotic cell?

Answer 8

A single cellular organism, they have cytoplasm and a cell membrane surrounded by a cell wall (which doesn’t contain cellulose) and a plasmid (which is freely moving inside the cytoplasm)

Question 9

What is active transport?

Answer 9

The movement of substances from an area of low concentration to an area of high concentration against the concentration gradient.

Question 10

What are xylem cells?

Answer 10

• Transpiration
• Moves water and minerals from the roots to the shoots to the leaves
• The structure has a strong cellulose cell wall and continuous columns of dead hollow cells.

Question 11

What are phloem cells?

Answer 11

• Translocation
• Moves glucose created by photosynthesis in the leaves to the rest of the plant for food
• The structure is a series of columns of living cells

Question 12

What is in interphase? The first stage

Answer 12

G1, S and G2 phases

Question 13

What is in the mitosis phase? The second stage

Answer 13

Mitosis and cytokinesis

Question 14

What happens during interphase?

Answer 14

• The cell prepares to divide
• G1: the cell grows and new organelles and proteins are made
• S: DNA synthesis, this is when the cells DNA is copied e.g. 46 chromosomes are doubled to 96
• G2: the cell keeps growing

Question 15

What happens during mitosis?

Answer 15

• The chromosomes become shorter and thicker to fit into the smaller dividing cells.
• The chromosomes line up along the centre of the cell
• They get pulled to opposite ends (poles) of the cell
• Cytokinesis: the cytoplasm divides to produce twin genetically identical cells.

Question 16

What is the purpose of mitosis?

Answer 16

• To replace worn or damaged cells
• To repair damaged tissue (e.g. Bone/muscle)
• To grow

Question 17

Wha is differentiation?

Answer 17

When cells in their early stage become specialised for particular functions, they cannot change into a different type of cell.

Question 18

What is cell division used for in animals?

Answer 18

It is restricted to replacement and repair, but in plants they keep the ability to differentiate.

Question 19

Sources of stem cells?

Answer 19

• Embryos (embryonic stem cells)

- Bone marrow (adult stem cells)

Question 20

Examples of treatments stem cells could provide?

Answer 20

• Spinal cord injuries
• Diabetes
• Could restore eyesight in the blind
• Skin grafting

Question 21

What is a tissue?

Answer 21

A group of cells with similar structure and function working together

Question 22

What is an organ?

Answer 22

Organs are collections of tissues, each organ contains several tissues working together to perform a specific function.

Question 23

What is a catalyst?

Answer 23

It speeds up the chemical reaction but is not used up in the reaction itself. It can be used over and over again.

Question 24

What are enzymes?

Answer 24

They are biological catalysts which catalyse specific reactions in living organisms.

Question 25

What is the shape and molecular structure of an enzyme?

Answer 25

Enzymes are large protein molecules, it has long chains of amino acids which are folded to produce a molecule with an activation site. This site has a unique shape so that it can bind to a specific substrate molecule.

Question 26

How does the lock and key theory work?

Answer 26

• The enzyme first combines with the substrate at the activation site
• The substrate fits into the activation site
• The substrate splints into its products and leaves the activation site
• The enzyme is ready to use again with no change to it

Question 27

What is metabolism?

Answer 27

The sum of all the reactions in a cell or the body

Question 28

What are the key factors that effect enzyme reaction rate?

Answer 28

Temperature and PH, the optimum temperature for enzymes in the bod is 37 degrees (body temperature).

Question 29

What does denatured mean?

Answer 29

When an enzyme has had too high of a temperature and the long amino acid chains have begun to unravel. When an enzyme is denatured it can no longer act as a catalyst, so the rate of reaction drops drastically.

Question 30

How does PH effect enzymes?

Answer 30

The shape of the activation site comes from the forces between the different parts of the protein molecule. These forces hold the folded chains in place. A change in PHeffects these forces and so a drastic change in PH may prevent an enzyme from working completely.

Question 31

Why does the digestive system break down food?

Answer 31

It breaks down food so it is small enough to fit into the bloodstream so that glucose can travel to the cells and organs to create energy.

Question 32

Which enzyme focuses carbohydrates?

Answer 32

Amylase catalysts the break down of carbohydrates into sugars in your mouth and small intestine.

Question 33

Which enzyme focuses proteins?

Answer 33

Protease catalyses the break down of proteins into amino acids in your stomach pancreas and small intestine.

Question 34

Which enzyme focuses fats?

Answer 34

Lipase catalyses the break down of fats into fatty acids and glycerol in the small intestine and pancreas.

Question 35

Why does the stomach include hydrochloric acid?

Answer 35

Because it provides a suitable PH for the protease working there to work efficiently.

Question 36

What is alkaline bile used for?

Answer 36

Alkaline bile is used to neutralise the acid coming from the stomach and gives a high PH for the enzymes of the pancreas and small intestine to work well.

Question 37

What is bile?

Answer 37

It is not an enzyme as it does not break down fat molecules. Instead it emulsifies the fat into tiny droplets to increase the rate of reaction.

Question 38

What is an advantage and disadvantage of a light microscope?

Answer 38

• They are cheaper and easier to use

- They have poor axial resolution, ie they cannot measure depth nearly as well as other microscopes

Question 39

What is an advantage and disadvantage of an electron microscope?

Answer 39

• It has extremely high magnification

- It is very expensive, large and requires lots of maintenance

Question 40

What is the formula for magnification?

Answer 40

IAM

Image size = actual size x magnification