Biology: Cells And Control Flashcards

1
Q

What does a nucleus contain?

A

Your genetic material in the form of chromosomes

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2
Q

What are chromosomes?

A

Coiled up lengths of DNA molecules

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3
Q

What do body cells usually have in terms of chromosomes? What does this make the cell? Where do these come from?

A

Body cell has two copies of each chromosome, magic the cell a diploid cell. One chromosome comes from organisms ‘mother’, one from ‘father’

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4
Q

What is the result of miosis?

A

Two cells identical to the original cell. Nucleus of each new cell contains same number of chromosomes as original cell.

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5
Q

What does the cell cycle produce?

A

New cells, to replace damaged cells and to grow as an organism

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6
Q

What is the cell cycle?

A

The process in which body cells in multicellular organisms divide to produce new cells during a process called the cell cycle.

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7
Q

What is the stage of the cell cycle when the cell divides called?

A

Mitosis

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8
Q

What is mitosis in the cell cycle?

A

The stage where the cell divides

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9
Q

What is it called when organisms use mitosis to produce?

A

Asexual reproduction

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10
Q

What are the three purposes of mitosis?

A

Growth, repair, asexual reproduction

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11
Q

What are the main phases of the cell cycle?

A

Interphase, mitosis and cytokinesis

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12
Q

What happens in interphase?

A

DNA is spread out in long strings. Cell grows to increase amour to of subcellular structures such as mitochondria and ribosomes. Then duplicates DNA.

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13
Q

Give the four steps of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

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14
Q

What happens in prophase?

A

Chromosomes condense, membrane around nucleus breaks down, so chromosomes lie free in the cytoplasm

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15
Q

What happens in metaphase?

A

Chromosomes line up at centre of cell

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16
Q

What happens in anaphase?

A

Cell fibres pull chromosomes apart. Two arms of each chromosome go to opposite ends of the cell

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17
Q

What happens in telophase?

A

Membranes form around each of the sets of chromosomes. These become nuclei of the two new cells.

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18
Q

What happens in cytokinesis?

A

Cytoplasm and cell membrane divide to form two separate cells

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19
Q

When does cytokinesis take place?

A

Before telophase ends

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20
Q

What is the formula to calculate the number of cells there’ll be after multiple divisions of cells by mitosis?

A

Number of cells = 2^n

N= number of divisions by mitosis

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21
Q

You start with 1 cell. After 5 divisions of mitosis, how many cells will there be?

A

2^5 = 2x2x2x2x2 = 32 cells

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22
Q

What is growth?

A

An increase in size of mass

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23
Q

What is cell differentiation?

A

The process by which cell changes to become specialised for its job, allowing multicellular organisms to work more efficiently

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24
Q

What is cell elongation?

A

Where the cell expands, making the cell bigger and so making the plant grow

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25
Q

What are the three ways in which cells grow and develop?

A

Cell differentiation
Cell division
Cell elongation

26
Q

How is the rate at which cells divide by mitosis controlled?

A

By the chemical instructions (genes) in the organisms DNA

27
Q

When does uncontrollable cell division happen? What can it result in?

A

If there’s a change in one of the genes that control cell division, the cell may start dividing uncontrollably. This can result in a mass of abnormal cells called a tumour.

28
Q

What are percentile charts used for?

A

To monitor growth

29
Q

How do people asses a child’s growth over time?

A

They use a growth chart, to see the overall patter in development

30
Q

What measurements are taken during a growth monitoring of a baby?

A

Length, mass and head circumference

31
Q

What does the 50th percentile in a growth chart tell you?

A

The mass 50% of babies will have reached at a certain age

32
Q

What are undifferentiated cells called?

A

Stem cells

33
Q

How do stem cells become specialised?

A

They’re given instructions and then divide through mitosis. These new cells then differentiate

34
Q

Which stem cells can turn into any kind of cell?

A

Embryonic stem cells

35
Q

Where can adult stem cells be found ?

A

Bone marrow

36
Q

What do adult stem cells do?

A

Replace damaged cells

37
Q

What are meristem cells? Where are they found?

A

The only plant cells that divide by mitosis. They’re found in the plant tissues, in the areas of pants that are growing e.g. Tips of roots

38
Q

What do meristem cells do?

A

Produce unspecialised cells that are able to divide and form and cell type in the plant for as long as the plant lives

39
Q

What is a disease that can be cured with adult stem cells. How?

A

Sickle cell anaemia can sometimes be cured with bone marrow transplant, as the adult stem cells produce new blood cells

40
Q

What are scientists looking to do with embryonic stem cells?

A

Growing them to replace cells which have even damaged by disease and injury

41
Q

What are the four main risks/drawbacks of experimenting with stem cell medicines/transplants?

A

Tumour development as stem cells divide rapidly, disease transmission from infected stem cells, rejection as they are foreign cells, ethical issues as human embryos are potential human lives

42
Q

What is the nervous system made up of?

A

Lots of neurones (nerve cells) that go to all parts of the body

43
Q

What are sensory receptors?

A

Groups of cells which can detect a change in your environment (a stimulus)

44
Q

What happens when a stimulus is detected by a receptor?

A

The information is converted to a nervous (electrical) impulse and sent along sensory neurones to the CNS (brain and spinal cord)

45
Q

What does the CNS consist of? What does it do?

A

Brain + spinal cord, is coordinates a response to impulses, which travel through CNS along relay neurones

46
Q

What does the CNS do with electrical impulses?

A

Send them to an effector muscle o gland, along a motor neurone.

47
Q

What is a reaction time?

A

Time it takes to respond to a stimulus

48
Q

Give the seven ‘steps’ of the reflex arc?

A

Stimulus > receptor > sensory neurone > CNS> motor neurone > effector > response

49
Q

What is the structure of a sensory neurone? How does it work?

A

One long dendron carries nerve impulses from receptor cells to the cell body, located in the middle of the neurone. One short axon carries nerve impulses from the cell body to the CNS.

50
Q

What is the structure of a motor neurone? How does it work?

A

Many short dendrites carry nerve impulses from the CNS to the cell body. One long axon carries nerve impulses from the cell body to the effector cells

51
Q

What is the structure of a relay neurone? How does it work?

A

Many short dendrites carry nerve impulses from sensory neurones to the cell body
An axon carries nerve impulses from the cell body to motor neurones

52
Q

What is the connection between two neurones called?

A

A synapse

53
Q

What does a synapse do?

A

Connect two neurones

54
Q

How are nerve signals transferred between two neurones?

A

By chemicals called neurotransmitters which diffuse across the gap (synapse), and then set off a new electrical signal in next neurone

55
Q

When does the transmission of nervous impulses slow down?

A

When passing between neurones, because diffusion of neurotransmitters takes time

56
Q

What are reflexes?

A

Automatic responses to stimuli.

57
Q

What is the passage of information in a reflex (from the receptor to the effector) called?

A

The reflex arc

58
Q

Where does a reflex in a reflex arc go through OR to

A

Through the spinal cord or through an unconscious part of the Brain

59
Q

Describe the six steps of the reflex arc, starting with a bee stinging a finger

A

1) bee stings finger
2) stimulation of the pain receptor
3) impulses travel alone the sensory neurone
4) impulses are along relay neurone, via synapse
5) impulses travel alone motor neurone, via synapse
6) impulse reaches muscle, it contracts and moves hand away from bee

60
Q

Describe how a reflex helps to protect the eye

A

Light receptors in the eye detect very bright light, and send message along sensory neurone to brain. Message travels along relay neurone to motor neurone, which tells circular muscles in iris to contract, making pupil smaller