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Biology > SB2 - Cells And Control > Flashcards

SB2 - Cells And Control Flashcards

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1
Q

What’s the cell cycle

A

A process to repair and require new cells for growth

Make new cells

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2
Q

How many chromosomes do human body cells have

A

23 pairs and 46 in total

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3
Q

What are cells with 2 sets of chromosomes called

A

Diploid

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4
Q

What are haploid cells

Give me an example too

A

When a cell contains only 1 copy of each chromosome

Gametes are haploid (sex cells)

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5
Q

How many phases are in the cell cycle

A

2

Interphase and mitosis

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6
Q

Tell me about the interphase

A

Cell makes extra sub cellular cell parts eg mitochondria. DNA replication also occurs

Copies of chromosomes are made, copies stay attached to eachother and look like X’s

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7
Q

Tell me about mitosis

A

The second stage in the cell cycle

Cell splits to form 2 daughter which are identical to parent cell

It occurs in a series of stages

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8
Q

Tell me about the prophase

A

Nucleus starts to break down and spindle fibres appear

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9
Q

Tell me about the metaphase

A

The chromosomes are lined up on the spindle fibres accross the middle of the cell

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10
Q

Tell me about the anaphase

A

The chromosome copies are separated and moved to either end of the cell on the spindle fibres

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11
Q

Tell me about the telophase

A

A membrane forms around each set of chromosomes to form nuclei

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12
Q

Tell me about cytokinesis

A

A cell surface membrane forms to separate the 2 cells during cytokinesis

Cell walls form in plant cells

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13
Q

What’s asexual reproduction

A

Some organism can reproduce with just one parent

They produce clones

Relies on mitosis

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14
Q

What are clones

A

Means their cells have the same chromosomes as parent (genetically identical)

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15
Q

Which is faster sexual or asexual reproduction

A

Asexual Becuase organisms do not need others

Though sexual produces variation

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16
Q

What are cancer cells

A

Sometimes cells turn in to cancer cells and undergo uncontrollable division

Rapid division lead to growing link or tumours that c an damage body and result in death

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17
Q

What is growth

A

An increase in size as a result of an increase in number or size of cells

Cell number increased due to division by mitosis

Can be recorded by taking measurements over time, such as length or mass

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18
Q

What’s a percentile

A

For example 25% of babies will have masses below the 25th percentile so 75% will be below the 75th percentile line

So if the 25th percentile for an 8 month baby is 8kg then 25% of 8 month old babies have a mass below this value

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19
Q

What’s differentiation

A

A process that changes less specialised cell into more specialised ones

Then adapt to a new function

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20
Q

How is a red blood cell adapted

A

It has not nucleus so there’s more space for red haemoglobin molecules which carry oxygen

Also has a large surface area which allows oxygen to diffuse in and out more quickly

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21
Q

How are fat cells adapted

A

The cytoplasm is filled with large fat droplets

The fat is stored until
The body needs more energy

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22
Q

How are neurones adapted

A

Have a long fibre that carries electrical impulses around the body and many connections to other neurones

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23
Q

How are muscle cells specialised

A

Contain special contractile proteins that can shorten the cell

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24
Q

What are meristems

A

A group of cells near the end of each shoot and root that allows the plant to continue growing throughout their lives

The cells in meristems divide rapidly by mitosis

Many of these cells increase in length (elongation) and differentiate

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25
Q

Tell me some examples of specialised plant cells

A

Root hair cells

Xylem cells

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26
Q

How is a xylem vessel made

What’s it like

A

From dead xylem cells

It has a thickened wall to withstand water pressure

Tiny pores in wall allow water and mineral salts to enter and leave the vessel

There’s no cytoplasm so vessel is empty

Loses cell walls to form a tube

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27
Q

How can you measure the percentage changes of growth in plants

A

Final value - starting value divided by the starting value X 100%

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28
Q

What are stem cells

A

Cells that divide repeatedly over a long period of time to produce cells that then differentiate

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29
Q

Where are stem cells found in plants

A

Meristems (roots and shoots)

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30
Q

What are plant stem cells like

A

Usually able to produce any kind of specialised cell throughout their life

Not like most animals especially vertebrates

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31
Q

What are embryonic stem cells

A

The cells of an early stage embryo

They can produce into any type of specialised cell

As the cells starts to divide the embryo starts to develop different areas that will become different organs

The stem cells in these areas become more limited in the types of specialised cell they can produce

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32
Q

What are adult stem cells

A

When an animal is fully developed the stem cells usually only produce one type of specialised cell that is in the tissue around them

They allow tissues to grow and replace old or damaged cells

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33
Q

What else can stem cells be used for

A

Treating diseases caused by damaged cells

Scientists studied to use adult and embryonic stem cells to treat diseases such as type 1 diabetes or to replace damaged cells

This is done by stimulating stem cell to make them produce the specialised cells that are needed them injecting them where needed

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34
Q

What are some of the problems with using stem cells

A

If stem cells continue to divide inside body after being replaced they can cause cancer

stem cells from one person are often killed by the immune system of other people that are put into - called rejection

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35
Q

Where is the cerebral cortext

A

It’s divided into 2 cerebral hemispheres at the front of the brain

36
Q

Where’s the cerebellum

A

Under the back of the brain near the spinal cord

37
Q

What’s the cerebral cortex

A

Makes up 80% of brain

Used for most of our senses, language, memory, behaviour and consciousness

Divided into 2 cerebral hemispheres

38
Q

What does the right hemisphere do

A

It communicates with the left side of the body

RIGHT Hemisphere communicate with the LEFT side of body

39
Q

What does the left hemisphere do

A

Communicates with the right side of body

40
Q

Tell me about the cerebellum

A

The base of the brain, the area is divided into 2 halves and controls bosh and posture

Coordinates the timing and fine control of muscle activity making sure movements are smooth

41
Q

What’s the medulla oblongata

A

Controls your heart rate and breathing rate

Responsible for reflexes such as vomiting, sneezing and swallowing

42
Q

What’s the spinal cord

A

The neurones that comedy to the medulla oblongata connect to the spinal cord

It’s about the width of a finger and consists of many nerves to carry info between the brain and rest of body

43
Q

What are neurones

A

Bundles of neurones

44
Q

In brain surgery what can electrodes be used for

A

Apply electrical currents to the brain

If patients are awake they can be asked what they feel

A current may also make the patient do something or stop an action occurring

This allows the functions of the brain to be investigated

45
Q

What does scanning allow us to do

A

Look deeper into the brain than surgery does

Allows the study of healthy individuals without risk of damaging brain

46
Q

What does a CT shape show

A

Shows the shapes of structures in the brain

An X-ray bean moves in a circle around the head and detectors measure the absorption of the X-rays

A computer used this to build a view of inside the body as a series of “slices” differences in the shapes in the brain can be linked to the function of those parts

47
Q

What’s a PET scan

A

Shows brain activity as the patient is injected with radioactive glucose

Most active cells take in glucose than less active ones (for respiration) the radioactive atoms cause gamma rays which the dabbed defects

The more gamma rays coming from a certain area contain more active cells

48
Q

What can spinal cord damage do

A

Reduces the flow of information between the brain and parts of the body

Nerve damage in the lower spinal cord can cause loss of feeling and use of legs

49
Q

What’s quadriplegia

A

Damage of the spinal cord in the neck can cause loss of use of both arms and legs

50
Q

Are there any cures for spinal cord damage

A

No adult stem cells can differentiate into neurones in spinal cord so no new neurones cannot be made to repair damage

Wires can be used to stimulate nerves and muscles below the damage but patients do not regain full movement of feeling

Treatments using stem injections are being developed

51
Q

What’s a brain tumour

A

When cancer cells often divide rapidly to form a tumour

52
Q

What are the effects of a brain tumour

A

May squash parts of the brain and stop them working

53
Q

How can brain tumours be treated using radiotherapy

A

Tumours can be cut or killed using radiotherapy (high energy X Ray beams)

Can damage body and brain

54
Q

Who can chemotherapy be used to treat s brain tumour

A

Injecting drugs that kill actively dividing cells

Can damage body and brain

55
Q

Why Might chemotherapy not work

A

Due to the blood- brain farrier (a natural filter that only allows certain substances to get from the blood into the brain mainly due to fells in capillary walls fitting very close together

So chemicals won’t enter to kill cells

56
Q

How can scientists study how the brain works

A

By growing brain tissue in a lab using stem cell techniques

57
Q

What’s the vertebra

A

24 bones form the backbone to protect spinal cord

58
Q

What’s the sciatic nerve

A

The thickest nerve that connects to the heal of the spinal cord

59
Q

What is the central nervous system

A

(CNS) and it’d the brain and spinal cord which controls your body

Nerves make up the rest of Your nervous system - allows the parts of your body to communicate using electrical signals called impulses

60
Q

What’s a stimulus

A

Anything your body is sensitive to including inside your body and your surroundings

61
Q

Give me some examples of sense organs

A

Eyes, ears, skin

62
Q

What detect stimuli

A

Sense organs that contain receptor cells

Eg. Skin contains receptor cells that detect the stimulus of temperature change

63
Q

How do receptor cells crest a response

A

Receptor cells crest impulses which usually travel to the brain, the brain processes this information and can send impulses to the other parts of the body to cause something to happen (a response)

64
Q

What’s neurotransmission

A

The travelling or transmission of impulses

Happens in neurones

65
Q

What’s a sensory neurone (there are different types)

How does neurotransmission happen

A

It’s function is to carry impulses from receptor cells towards the CNS

A receptor cells impulse passes into a tiny branch Called a DENDRITE

Then it’s transmitted along the DENDRON and AXON

A series of axon terminals allows impulses go be transmitted to other neurones

66
Q

What are dendrons and axons like(how are they adapted)

A

Frequently long to allow fast nuerotransmission over long distances

Also have a fatty layer surrounding these parts called the myelin sheath - is electrically insulates a neurone from neighbouring neurones, stopping the signal Losing energy
May also make an impulse jump along the cell between gaps in the myelin and so speed up neurotransmission

67
Q

What do dendrites do

A

Receive impulses from receptor cells

68
Q

What do axons do

A

Pass impulses on to other neurones

69
Q

Where in the eye does it contain receptors

A

The retina - the back of the eye

70
Q

What are cones

A

Receptor cells that are sensitive to the colour of light. Some cones detect red light while others detect green or blue

They generate impulses in sensory neurones that lead into the brain through the optic nerve

The information from all the cones is processed into full colour vision in the cerebral hemispheres

71
Q

What are rods

A

Receptor cells that detect differences in light intensity not colour

Rods work well in very dim light whereas cones only work in very bright light

72
Q

What’s the iris

A

The coloured part of the eye, the amount of light entering the eye is controlled by muscles in the iris

Which can constrict the pupil (decrease diameter) or dilate it (make it bigger)

Bright light can damage receptor cells in the retina

73
Q

What’s the cornea

A

Clear colourless covering over eye that focuses light,

It refracts light to bring them together

74
Q

Where’s the pupil

A

The dark area in the middle of the eye where light enters

75
Q

What are the ciliary muscles

A

They make the lens fatter to focus light from near objects and thinner to focus light from distant objects

76
Q

What’s the lens

A

It fine tuned the dividing to produce a very clear image

77
Q

What’s being short sighted like

A

Distant objects appear blurred

There are 2 reasons
The eyeball is too long

The cornea is too curved and bends the Rays more than is should

Longsighted is the opposite

78
Q

How can we fix short and long sightedness

A

Contact lenses or glasses of a laser can be used to cut away some of the cornea and reshape it

79
Q

What’s a cataract

A

Sometimes a protein builds up inside the lens to make it cloudy

It can be restored by replacing the clouded lens with a plastic one

80
Q

How is colour blindness caused

A

Due to some cones not working properly - the most common is red-green colour blindness in which the cones that detect green of it are faulty so it’s difficult to tell apart

It can’t be corrected

81
Q

What are the effectors

A

They carry out at action

When a brain coordinates a response to a stimulus impulses are sent to the effectors

They include muscles and glands

82
Q

What are motor neurones

A

They carry impulses to effectors

No DENDRON, dendrites on the cell body

83
Q

What are relay neurones

A

They are short neurones that are found in spinal cord, they link motor and sensory neurones

Also make up a lot of nerve tissue in brain

No DENDRON

Dendrites are on the cell body

84
Q

What’s a synapse

A

It contains a tiny gap when an impulse reaches an axon terminal, a neurotransmitter substance is released into the gap, it’s detected by the next neurone which generates a new impulses

Synapses slow down neurotransmission by are useful becuase neurotransmitters are only released from axon terminals and so impulses flow in one direction

Also allows many fresh impulses to be generated in many neurones connected to one neurone - the originals impulse does not less to be split and lose strength

85
Q

What’s a reflex

A

Reflex actions are responses that are automatic and extremely quick to protect the body

They use neurone pathways called reflex arcs which bypass the parts of the brain involved in processing information and so are quicker than responses that need processing

86
Q

Tell me the order of a response

A 
Stimulus 
Receptor
Sensory neurone
Relay neurone
Motor neurone
Response

Biology (12 decks)

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