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Biology > Unit 2 - Cells And Control > Flashcards

Unit 2 - Cells And Control Flashcards

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1
Q

Describe the process of the cell cycle.

A

Starts with interphase - the chromosomes in a diploid cell replicate. (DNA replication)
The copies stay attached and form X-shapes.
Mitosis - copies of chromosomes separate and each daughter cell ends up with the same amount of chromosomes as the parent cell.

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2
Q

How many chromosomes does a human body cell contain?

A

It contains two copies of 23 types of chromosomes, making 46

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3
Q

What type of cells are gametes?

A

Haploid, only contain one set of chromosomes.

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4
Q

Describe the stages of mitosis.

A

Prophase - spindle fibres appear
Metaphase - chromosomes line up along the spindle fibres
Anaphase - chromosomes are pulled apart to either end of the cell by the spindle fibres.
Telophase - a membrane forms to form the nuclei
Cytokinesis - cell membrane forms to separate the cells.

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5
Q

What does mitosis produce?

A

Two daughter cells that are genetically identical.

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6
Q

What type of cell division does asexual reproduction rely on?

A

Mitosis

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7
Q

Why are cancer cells deadly?

A

The cells divide uncontrollably which creates tumours which can result in death.

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8
Q

How can growth be recorded?

A

By taking measurements over time, length or mass.

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9
Q

What does a percentile show?

A

It shows what percentage of readings are below a certain value.

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10
Q

Why are percentile charts useful?

A

For growth of babies, they allow us to see whether the baby is growing at a normal rate and how big it is compared to other babies of the same age.

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11
Q

Why is cell differentiation useful?

A

So they can carry out specific functions needed.

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12
Q

Give two examples of specialised cells and their adaptations.

A

Red blood cell - no nucleus allows more space for molecules carrying oxygen. Large surface area allows oxygen to diffuse in and out quickly.
Fat cells - the cytoplasm is filled with large fat droplets which sore energy until it is needed.

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13
Q

Describe what meristems are.

A

A group of cells found at the end of shoots and roots that divide rapidly by mitosis allowing the plants to grow throughout their lives.

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14
Q

How is a xylem vessel adapted?

A

Thick walls - hold against water pressure
No cell wall between cells - forms a tube
No cytoplasm - empty to allow water to pass.

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15
Q

How do yo u work out a percentage change?

A

Final value - starting value/ starting value X 100

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16
Q

Cell before they differentiate are called…

A

Stem cells

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17
Q

Where are stem cells found in plants?

A

In meristems.

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18
Q

What is the difference between embryonic and adult stem cells?

A

Embryonic stem cells can develop into any type of specialised cell but adult stem cells can only develop into specialised cells that are in the tissues surrounding them. They replace damaged or old cells.

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19
Q

How can stem cells be used to treat diseases?

A

Stimulate the stem cells to make them produce the specialised cells that are needed which are then injected into places where needed.

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20
Q

What problems are there for using stem cells to treat diseases?

A

If the stem cells continue to divide, this can cause cancer.

The stem cells that might be killed by the immune system of the person they are put into. (Rejection)

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21
Q

What do stem cells do when the embryo is three weeks old?

A

They start to differentiate to produce neurones that make up most of the brain.

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22
Q

What are the four main parts of the brain?

A

Cerebral cortex, cerebellum, medulla oblongata, spinal cord.

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23
Q

What is the cerebral cortex responsible for?

A

Language, senses, memory and behaviour.

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24
Q

What is the difference between the right cerebral hemisphere and the left?

A

The right communicates with the left side of the body and the left communicates with the right.

25
Q

Where is the cerebellum found?

A

At the back of the brain.

26
Q

What is the cerebellum responsible for?

A

Balance, posture and fine control of muscle activity.

27
Q

What does the medulla oblongata control?

A

Breathing rate, heart rate, reflexes (vomiting, sneezing, swallowing)

28
Q

What part connects the spinal cord to the brain?

A

Medulla oblongata.

29
Q

What is the spinal cord make from?

A

Many nerves which carry information between the brain and the rest of the body.

30
Q

What benefits does scanning give?

A

Allows scientists to look deeper into the brain.

Allows the study of a healthy individual without the risk of brain damage.

31
Q

How does a CT scan work?

A

An X-ray beam moves around the head and detectors measure the absorption of the X-rays. A computer uses the information to build a view of the inside of the brain. This can be used to detect brain tumours as they absorb more X-rays leaving white areas.

32
Q

How does a PET scan work?

A

A patient is injected with radioactive glucose. More active cells absorb the glucose more than less active cells. This causes gamma rays that show the activity in the brain.

33
Q

What does nerve damage in the lower spinal cord cause?

A

Loss in feeling and use of legs.

34
Q

What does damage in heck cause?

A

Quadriplegia, loss of use in legs and arms.

35
Q

Damage to the spinal cord reduces…

A

Flow of information between brain and parts of the body.

36
Q

Why can’t new neurones be made in the spinal cord?

A

There are no adult stem cells that can differentiate into neurones in the spinal cord.

37
Q

Why is a brain tumour deadly?

A

It can squash parts of the brain and stop them working.

38
Q

How can tumours be cut?

A

Radiotherapy - cut using X-ray beams.

Chemotherapy - drugs kill actively dividing cells.

39
Q

What is a blood-brain barrier?

A

A natural filter that only allowed certain substances to get from the blood into the brain.

40
Q

Where are the receptor cells found?

A

In the retina.

41
Q

What is the difference between cones and rods?

A

Cones detect colour but rods detect light.

There are three types of cones: red, blue and green.

42
Q

How does the information reach the brain from the eyes?

A

The cones and rods generate impulses in sensory neurones which lead into the brain through the optic nerve.

43
Q

Define the pupil.

A

A small hole in the eye which lets different amounts of light enter. The hole is controlled by the muscles in the iris which changes the size of the hole.

44
Q

What can damage the receptor cells?

A

Bright light.

45
Q

Explain the focusing process.

A

Most of the focusing is done by the cornea which refracts the light rays to one spot. The lens does the fine-tuning. The ciliary muscles makes the lens fatter to focus light from near objects and vice versa.

46
Q

Give three eye problems and what they are.

A

Short-sightedness: the person cannot see distance objects clearly.
Long-sightedness: the person cannot see close objects.
Colour blindness: the person has difficulty in seeing some colours.

47
Q

Can any of the eye problems be corrected?

A

Short and long-sightedness can be corrected using lenses to refract the light rays or the cornea can be reshape using a laser.

48
Q

What is a cataract?

A

When protein builds up inside the lens and makes it cloudy.

49
Q

Can a cataract be corrected?

A

Yes, the lens can be replaced by a plastic one.

50
Q

Can colourblindness be corrected?

A

No

51
Q

What do effectors do?

A

They carry out actions. For example muscles.

52
Q

What do motor neurones do?

A

They carry the impulses to the effectors. They don’t have dendrons.

53
Q

What are relay neurones?

A

Short neurones found in the spinal cord connecting the motor and sensory neurones. They don’t have dendrons.

54
Q

What is a synapse?

A

The gap between the neurones.

55
Q

What happens when an impulse reaches an axon terminal?

A

A neurotransmitter substance is released which is detected by the next neurone.

56
Q

One positive and negative about synapses.

A

Positive: only released form axon terminals so impulses flow in one direction.
Negative: they slow down neurotransmission.

57
Q

What is a reflex action?

A

An automatic action so the impulses don’t have to reach the brain before an action occurs.

58
Q

What is a reflex arc?

A

The path used for a reflex action. The impulses only reach the spinal cord.

Biology (9 decks)

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