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B2 - Cells and control Flashcards

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1
Q

What phase are cells in before they undergo mitosis?

A

Interphase

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2
Q

What are the different phases of mitosis in order?

A

Prophase, metaphase, anaphase, telophase

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3
Q

What happens in prophase?

A

The chromosomes condense and become visible under a microscope and the nuclear envelope starts to break down, leaving the chromosomes free in the cytoplasm

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4
Q

What happens in interphase?

A

The cells replicate their DNA and each chromosome becomes X-shaped

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5
Q

What is an X-shaped chromosome made up of?

A

2 identical chromatids

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6
Q

What happens in metaphase?

A

The chromosome line up in the middle of the cell

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7
Q

What happens in anaphase?

A

Spindle fibres contract and shorten to pull the chromatids to the opposite ends of the cell

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8
Q

What happens in telophase?

A

The chromatids reach the ends of the cell and uncoil to become long, thin chromosomes again. A nuclear envelope forms around each set of chromosomes to form nuclei

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9
Q

What happens in cytokinesis?

A

The cytoplasm divides, forming 2 daughter cells that are genetically identical

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10
Q

Is cytokinesis part of mitosis?

A

No but it is important for it - it is like an interphase only after the cell divides

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11
Q

What are the 4 reasons cells undergo mitosis?

A

Growth, reproduction, replacement and repair

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12
Q

What is the cell cycle?

A

The series of steps that takes place as a cell grows and divides

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13
Q

What are the steps of the cell cycle in order?

A

Cellular growth, DNA replication, more cell growth, mitosis and cytokinesis

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14
Q

What happens in cellular growth?

A

The cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes

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15
Q

What happens in DNA replication?

A

The chromosomes duplicate so each chromosome consists of two arms (copies)

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16
Q

What happens in more cell growth?

A

Don’t overthink it

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17
Q

What happens in mitosis?

A

The DNA divides in two

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18
Q

What happens in cytokinesis (broad description)

A

The cell splits in two

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19
Q

How many pairs of chromosomes do most human cells have?

A

23 pairs, so 46 chromosomes

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20
Q

Are the cells produced by mitosis genetically different?

A

No they are genetically identical

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21
Q

How many cells are produced in mitosis?

A

2

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22
Q

What do we call the cells produced by mitosis?

A

Daughter cells

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23
Q

What specialised cell is adapted to transmit messages?

A

Nerve cells

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24
Q

Give 3 ways a sperm cell is adapted to its function

A

Any 3 from
It has half as much genetic material as a normal cell to allow correct function when it joins with the egg cell
It has lots of mitochondria to provide energy for movement
It is streamlined to make swimming easier
It has digestive enzymes in its head to break through the wall of the egg

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25
What is differentiation?
The process by which cells become specialised
26
Name 2 cells that are adapted to their function by having a large surface area
Red blood cells and root hair cells
27
What are specialised cells?
Cells that are adapted to perform a specific function
28
What adaptation would you expect heart cells to have?
Lots of mitochondria to provide energy for constant heart beats
29
What are the two types of animal stem cells?
Adult stem cells and embryonic stem cells
30
What are the two key features of stem cells?
They can divide by mitosis to form more cells and can differentiate into specialised cells
31
How are embryonic stem cells formed?
When a sperm cell fertilises an egg cell they form a single cell that then divides by mitosis to form an embryo. The cells in this embryo are known as embryonic stem cells
32
What is a zygote?
The single cells formed from fertilisation
33
How are embryonic stem cells different to adult ones?
Embryonic stem cells can differentiate into any type of cell
34
Can adult stem cells divide by mitosis?
Yes
35
What type of cells can adult stem cells differentiate into?
Blood cells - white blood cells, red blood cells or platelets
36
Where are adult stem cells found in the body?
Bone marrow
37
What are meristems?
Plant cells that are continually growing and contain stem cells
38
What parts of a plant contain meristem tissue?
Root and shoot tips
39
Are plant stem cells there for their entire life
Yes
40
What is the problem in type 1 diabetes?
The pancreas is damaged and doesn't produce insulin
41
What is paralysis and how is it caused?
Paralysis is when you cannot move some of or all of your body, it is caused by damaged nerve cells no longer being able to send messages to the muscles
42
What are the steps of embryonic stem cell treatment?
Extract the embryonic stem cells from early embryos, grow them in a laboratory, stimulate them to differentiate into whichever type of specialised cell that we want and then give them to the patient to replace their faulty cells
43
What are 2 drawbacks of embryonic stem cell treatment?
The embryonic stem cells must come from embryos. These are in limited supply and some people have ethical objections to it as they think the embryos could have developed into a person. The cells could also be rejected by the person's immune system, as it would identify them as foreign
44
What are 2 advantages of using adult stem cells for treatment over embryonic stem cells?
Adult stem cells won't cause rejection as they are taken from the patient's body and are not in limited supply as they can be taken from the patient
45
What are 2 risks of using stem cells in medicine?
The stem cells could be infected by a virus whilst in the lab, which could then infect the patient and as they develop quickly t here is a chance they could divide uncontrollably once they've been transplanted and then become a tumour
46
Is stem cell research legal in the UK?
yes but it is highly regulated
47
Which two structures make up the central nervous system (CNS)?
The brain and spinal cord
48
What is a cross-section?
A view into the inside of something made by cutting through it
49
What is the biggest part of the brain at the top?
The cerebral cortex
50
How many hemispheres is the cerebral cortex split into?
2
51
What are the roles of the cerebral cortex?
Memory, Interpreting sense like hearing and vision and consciousness
52
What is the part of the brain at the bottom right corner when looking at it from the right?
The cerebellum
53
What are the roles of the cerebellum?
Balance and muscle co-ordination
54
What is the medulla responsible for?
Unconscious activities such as regulating breathing and heart rate
55
What part of the brain is responsible for regulating our body temperature?
The hypothalamus
56
Where in the brain is the medulla?
In the brain stem
57
What are the 3 main ways scientists can study the brain?
Study people with brain damage, electrically stimulate different parts of the brain and scan the brain using CT, PET, MRI, or fMRI scans
58
What are the 3 main reasons treating the brain is so difficult?
There is a huge range of things that can go wrong, from mental illness to infection, it is encased within the skull so is hard to access and is very complicated to hard to target with medication
59
What passes along nerve cells?
Electrical impulses
60
What is the gap between 2 neurones called?
A synapse
61
What is release across a synapse?
Chemicals
62
What is the role of a receptor?
To detect a stimulus
63
What is the role of a sensory neurone?
To transfer a signal from a receptor to the CNS
64
What is the role of a motor neurone?
To transfer a signal from the CNS to an effector
65
What is the role of a relay neurone?
To transfer a signal from a sensory neurone to a motor neurone
66
What is a relfex?
An automatic response to a stimulus
67
What is the pathway of a reflex arc?
Stimulus -> Receptor -> Sensory neurone, Relay neurone -> Motor neurone -> Effector -> Response
68
What are the 2 main types of effectors?
Glands and muscles
69
Why are reflexes important?
They protect us from harm
70
What is the cornea?
A transparent layer at the front of the eye that refracts light
71
What and where is the optic nerve?
A bundle of fibres that transmits information to the brain at the back of the eye
72
What and where is the retina?
A light sensitive layer of tissue lining the back of the eye that converts light into electrical signal for the brain to interpret as images
73
What is the pupil?
The gap through which light passes to reach the lens
74
What and where is the lens?
A clear curved structure at the front of the eye behind the pupil that focuses light rays that enter the eye through the pupil, making an image on the retina
75
What are the 2 types of receptor cells in the retina?
Cone and Rod cells
76
Which light sensitive cells in the retina enable you to see in colour?
Cone cells
77
Which two stimuli are the receptor cells of an eye sensitive to?
Colour and light intensity
78
Which light sensitive cells in the retina allow you to see in the dark?
Rod cells
79
What is the fovea and what is special about it?
The point where light focuses on the retina. This region contains the highest concentration of cone cells and gives the sharpest image
80
What is the purpose of the iris reflex?
To ensure the optimum amount of light enters the eye
81
When do we describe the pupil as dilated?
If the pupil is dilated, then it is very large
82
What two muscles make up the iris?
Radial and circular muscles
83
When the eye is exposed to bright light what does the pupil do?
It constricts to let less light through and prevent damage to the retina
84
What happens to the radial and circular muscles when the pupil constricts?
The radial muscle relaxes and the circular muscle contracts
85
What happens to the radial and circular muscles when the pupil dilates?
The radial muscle contracts and the circular muscle relaxes
86
When do we describe the pupil as constricted?
The the pupil is very small then it is constricted
87
Which to structures refract light entering the eye?
The lens and cornea
88
What shape should the lens be to refract light strongly?
Short and fat
89
What holds the lens in place?
Suspensory ligaments
90
What holds the suspensory ligaments in place?
The ciliary muscle
91
Can the ciliary muscle contract and relax?
Yes
92
Can the suspensory ligament contract and relax?
No
93
How do the ciliary muscles and suspensory ligaments make the lens short and fat?
The ciliary muscle contracts and the suspensory ligaments slacken
94
What happens to the ciliary muscle, suspensory ligaments and lens when trying to focus on a distant object?
The ciliary muscle relaxes, the suspensory ligaments are pulled taut and the lens is long and thin
95
What does long and short sighted mean?
If you are long sighted you cannot focus on nearby objects and if you are short sighted you cannot focus on far away objects
96
What type of glasses lens could fix long and short sightedness?
Concave for long sightedness and convex for short sightedness
97
Explain the effects of low levels of neurotransmitter in the communication between neurones
The neurotransmitter is released from the relay neurone (1), diffuses across the synapse (2), attaches to the motor neurone causing an impulse (3), low levels of neurotransmitter slow down impulse transmission (4), high levels increase rate of diffusion/ speed up impulse transmission (5)

Biology (6 decks)

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