B4

Question 1

What is respiration?

Answer 1

The process of transferring energy from the breakdown of glucose

Question 2

Why is ATP made?

Answer 2

Because the energy transferred by respiration cannot be used directly by cells so instead it is used to make ATP

Question 3

What is the balanced symbol equation for aerobic respiration?

Answer 3

C6H12O6 + 6O2 -> 6H2O + 6H2O

Question 4

What is aerobic respiration?

Answer 4

It occurs when there is lots of oxygen available- it breaks down glucose and combines it with oxygen to make water and CO2 (waste product)
It produces 32 molecules of ATP for every molecule of glucose (most efficient way)

Question 5

Where does aerobic respiration occur in prokaryotic cells?

Answer 5

In the cytoplasm

Question 6

Where does aerobic respiration occur in eukaryotic cells?

Answer 6

In the mitochondria

Question 7

What is anaerobic respiration?

Answer 7

It occurs when there is not enough oxygen present- it partially breaks down the glucose and for animals produces lactic acid (a waste product), whereas for plants it produces ethanol and CO2.
It produces only 2 molecules of ATP for every molecule of glucose (less efficient than aerobic)

Question 8

What does the cell cycle do?

Answer 8

It makes new cells for growth or repair

Question 9

Name the two phases of the cell cycle

Answer 9

Interphase and Mitosis

Question 10

Summarize interphase

Answer 10

The cell grows and increases the number of subcellular structures.
It then duplicates its DNA, so there’s one copy for each new cell.
The DNA forms X-shaped chromosomes, where each arm is a copy of the other

Question 11

Summarize mitosis

Answer 11

Cell fibres pull apart the chromosomes, making the two arms of the chromosome go to the opposite ends of the cell.
Membranes form around each set of chromosomes- these become the nuclei for the new cells. The nucleus divides.
Lastly, the cytoplasm and cell membrane divide.
The product is two new daughter cell, genetically identical to each other and the parent cell

Question 12

What are auxins?

Answer 12

Plant growth hormones- in shoots extra auxins accelerate growth and in roots extra auxins inhibit growth

Question 13

Explain positive phototropism of shoots

Answer 13

When a shoot is exposed to light, it accumulates more auxins on the shaded side, making the shaded side grow faster, causing it to bend towards the light

Question 14

Explain positive gravitropism of roots

Answer 14

A root growing sideways will have more auxins on its lower side, however, in roots auxins inhibit growth, causing the root to grow down

Question 15

Explain how phototropism and gravitropism helps plants to survive

Answer 15

Because it means the plant will grow towards the light, meaning it will absorb more light for photosynthesis and it will grow downwards, meaning the root is more likely to find more water and minerals

Question 16

What do animals and some bacteria produce during anaerobic respiration?

Answer 16

Lactic acid

Question 17

What do plants and some microorganisms produce during anaerobic respiration?

Answer 17

Ethanol and carbon dioxide

Question 18

What is cancer?

Answer 18

A case of uncontrollable cell division

Question 19

What are the advantages of electron microscopes? (2 things)

Answer 19

You can see things at a higher magnification and resolution

Question 20

What is the equation linking eyepiece lens magnification, objective lens magnification and total magnification?

Answer 20

Total magnification = Eyepiece lens magnification x Objective lens magnification

Question 21

Question:
If the eyepiece lens magnification of a microscope is 10, and the total magnification is 400, what is the objective lens magnification?

Answer 21

400/10=40

Answer: 40

Question 22

What is the equation linking magnification, measured size and actual size in microscopes?

Answer 22

Magnification = Measured size / Actual size

Question 23

In animals, what are the two gametes?

Answer 23

Sperm and egg cells

Question 24

What does each gamete contain?

Answer 24

23 chromosomes

Question 25

What does the fusion of the male and female gamete in animals produce?

Answer 25

A fertilised egg, known as the zygote

Question 26

Summarize division 1 of meiosis

Answer 26

• chromosomes line up in pairs
• pairs pulled apart
• some of the father’s chromosomes and mother’s chromosomes go into each new cell
• the chromosome number of each new cell is half that of the original cell

Question 27

Summarize division 2 of meiosis

Answer 27

• chromosomes line up again
• pulled apart
• 4 gametes are produced that are genetically different

Question 28

What are light microscopes?

Answer 28

Work by passing light through the specimen

-they let us see things like the nuclei and chloroplasts

Question 29

What are electron microscopes?

Answer 29

Use electrons rather than light

• higher magnification and resolution than light microscopes
• allow us to see internal structure of things like chloroplasts

Question 30

What is a feature of embryonic stem cells and what does that allow them to do?

Answer 30

They are unspecialised, meaning they are able to divide to produce any type of specialised cell (e.g. blood cells). All embryonic stem cells are unspecialised until the 8 cell stage

Question 31

What is the process of stem cells becoming specialised called?

Answer 31

Differentiation

Question 32

What are adult stem cells?

Answer 32

They are stem cells found in certain places like bone marrow, but they can only differentiate into certain types of cells

Question 33

All stem cells are unspecialised (True or False)

Answer 33

True

Question 34

What do meristems produce?

Answer 34

Unspecialised cells that are able to divide to form any cell type, however, unlike human stem cells, plant stem cells are able to do this for the whole of the plants life.

Question 35

What are risks of stem cell use in medicine? (2 things)

Answer 35

• Tumour development: stem cells divide very quickly, and if this is uncontrollable, a tumour may develop
• Disease transmission: viruses live inside cells and if these go undetected, then the disease will be passed on

Question 36

How can embryonic stem cells be used in medicine?

Answer 36

As stem cells are unspecialised, and can differentiate into any type of specialised cell, therefore it may be possible to use stem cells to replace those which have been damaged by disease or injury

Question 37

What is the main ethical argument against the use of embryonic stem cells?

Answer 37

In order to take out embryonic stem cells, the embryo will be destroyed- this means the destruction of a potential human life

Question 38

Explain negative gravitropism is shoots

Answer 38

A shoot growing sideways will gather more auxins on the lower side, causing it to grow faster, bending the shoot upwards

Question 39

Explain negative phototropism in roots

Answer 39

A root being exposed to the light will gather more auxins on the shaded side, and as in roots auxins inhibit growth, the root will bend downwards away from the light and further into the soil

Question 40

What is dormancy in plants?

Answer 40

When seeds won’t germinate (start growing)

Question 41

What do gibberellins do for a plant?

Answer 41

• They break the dormancy of seeds and allow germination
• They trigger a response called ‘bolting’, where the plant produces lots of flowers before death in order to maximise reproduction

Question 42

What does ethene do for a plant?

Answer 42

• It causes leaves to fall of the plant

- It stimulates the enzymes that causes fruit to ripen