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Biology 🌱 > Cells And Control > Flashcards

Cells And Control Flashcards

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1
Q

What are the stages of mitosis?

A

Interphase - the DNA copies itself

Prophase – the chromosomes condense so spindle fibres become visible, the nuclear membrane breaks down

Metaphase – chromosomes line up in the middle of the cell

Anaphase – one set of chromatids are pulled to each pole of the cell

Telephase – new nuclear membranes form around the groups of chromosomes

Cytokinesis – the cell membrane divides into two daughter cells

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2
Q

What are stem cells?

A
  • Completely undifferentiated cells
  • That can specialise into any type of cell
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3
Q

What are meristems?

A
  • Parts of a plant where growth occurs (root and shoot tips)
  • Don’t ever fully differentiate, stay as stem cells
  • Can be used to grow clones quickly and cheaply to protect from extinction or if it has desirable features
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4
Q

What are the two types of animal stem cells?

A

Embryonic - removed from the embryo and can differentiate into any cell type

Adult - found in limited numbers and locations in the body

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5
Q

What are some of the uses for embryonic stem cells?

A
  • Replacing or repairing brain cells to treat Parkinson’s disease
  • Replacing the damaged cells in the retina to treat some kinds of blindness
  • Grow new tissues in the lab for transplants or drug testing
  • To replace insulin producing cells for diabetics
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6
Q

What are the advantages and disadvantages of embryonic stem cells?

A

Advantages:
- Easy to extract from embryo
- Produce any type of cell

Disadvantages:
- Embryo destroyed when cells removed, some people think embryos have a right to life

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7
Q

What is the risk of all stem cells?

A

They may not stop dividing so may cause cancer

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8
Q

What are the advantages and disadvantages of adult stem cells?

A

Advantages:
- No embryo destroyed so not an ethical issue
- If taken from the person treated, it will not cause rejection by the body

Disadvantages:
- Only produces few types of cells

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9
Q

What are some of the functions of the cerebral hemispheres?

A
  • Consciousness
  • Memory
  • Intelligence
  • Visual and sensory processing
  • Personality
  • Senses
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10
Q

What do the two cerebral hemispheres make up?

A

Cerebrum

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11
Q

What is the function of a cerebellum?

A

Controlling fine movements of muscles e.g. coordination and balance

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12
Q

What is the function of the medulla oblongata?

A

Controls subconscious activities e.g. heart rate, breathing rate, digestion, swallowing and sneezing

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13
Q

How does a CT scan work?

A
  • X-ray radiation is fired at the brain from different angles
  • This generates a 3-D image of the brain
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14
Q

How does a PET scan work?

A
  • A radioactive tracer is injected into the blood
  • The tracer will build up in areas of rapid respiration and will be highlighted on the scan
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15
Q

How does the nervous system work?

A
  • Receptors convert a stimulus into an electrical impulse
  • Impulses travel along sensory neurons to the CNS
  • The information is processed and appropriate response is coordinated
  • An electrical impulse is sent along motor neurones to effectors
  • Effectors carry out the response
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16
Q

What are the stages of the reflex arc?

A
  • Receptors in the skin detect a stimulus and transmit a signal to sensory neurones
  • Sensory neurons send electrical impulses to relay neurones in the spine
  • They connect sensory neurons to motor neurones
  • Motor neurones send electrical impulses to effector
  • The effector produces a response
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17
Q

What are the features of sensory neurones?

A
  • Dendrites to receive impulses from receptor cells
  • Dendrons and axons to allow fast transmissions over long distances
  • Cell body which contains the nucleus
  • Myelin sheath that insulates the neuron stopping energy loss and allows impulse to jump between gaps speeding up transmission
  • Axon terminals to pass impulses to other neurons
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18
Q

How is an impulse transmitted over a synapse?

A
  • Synapse is a gap between neurons
  • An electrical impulse stimulates the release of chemical messengers called neurotransmitters
  • Neurotransmitters diffuse across the synapse
  • This stimulates an electrical impulse in the next neurone
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19
Q

What is the function of the cornea?

A

Refracts light onto the retina

20
Q

What is the function of the iris?

A
  • Muscles that surround the pupil that contract or relax to alter the size of it
  • Controls how much light enters the pupil
21
Q

What is the function of the lens?

A

Further refracts light to focus it onto the retina

22
Q

What is the function of the retina?

A
  • Layer of the light-sensitive cells found at the back of the eye that are stimulated when lights hits them
  • Contains rod and cone cells which convert light to nerve impulses
23
Q

What is the function of the optic nerve?

A

Carries impulses between the eye and brain

24
Q

What is the function of the ciliary muscles and suspensory ligaments?

A
  • Holds the lens in place
  • Control its shape and allow us to focus on objects near or far away
25
Q

What is the difference between a rod and cone cells?

A

Rod cells - more sensitive to light so useful for seeing in dim light

Cone cells - sensitive to bright light and allow colour vision

26
Q

What is accommodation?

A

The process of changing the shape of the lens to focus on near or distant objects

27
Q

How does the eye adapt to a near object?

A
  • Ciliary muscles contract
  • Suspensory ligaments loosen
  • Lens is thicker and more curved
  • Light is refracted strongly
28
Q

How does the eye adapt to a far away object?

A
  • Ciliary muscles relax
  • Suspensory ligaments tighten
  • Lens becomes thinner
  • Light is only refracted slightly
29
Q

How does the eye adapt to bright light?

A
  • The circular muscles in the iris contract and radial muscles relax
  • To make the pupil smaller
  • This avoids damage to the retina
30
Q

How does the eye adapt to dim light?

A
  • Circular muscles in the iris relax and radial muscles contract
  • To make the pupil larger
  • So more light can enter to create a better image
31
Q

What is shortsightedness? (+ name)

A
  • Myopia
  • The lens is too curved so distant objects appear blurry
32
Q

What is long sightedness? (+ name)

A
  • Hyperopia
  • The lens is too flat so it cannot refract light enough
33
Q

What are cataracts?

A
  • Clouding of the lens
  • Can often occur congenitally (from birth) but can also develop over time
  • They restrict vision
34
Q

How can cataracts be treated?

A

By removing the lens and replacing with an artificial lens (plastic)

35
Q

What is colour blindness caused by?

A
  • Occurs when people do not have enough cone cells in their retina
  • Usually genetic
36
Q

What are the causes of shortsightedness?

A
  • Elongated eyeballs, so the distance between lens and retina is too big
  • Lens being too thick and curved, so light is focused in front of the retina
37
Q

What are the causes of long sightedness?

A
  • Eyeball being too short, so the distance between lens and retina is too small
  • Loss of elasticity in the lens, meaning it cannot become thick enough to focus
38
Q

How can shortsightedness be corrected?

A

By placing a concave lens in front of the eye

39
Q

How can long sightedness be corrected?

A

By placing a convex lens in front of the eye

40
Q

What is laser eye surgery?

A
  • Lasers either used to reduce the thickness of cornea (to refract less light) to treat short sightedness
  • Or to change its curvature (to refract light more strongly) to treat long sightedness
41
Q

What does mitosis produce?

A

Two genetically identical daughter diploid cells

42
Q

What is the structure of DNA?

A
  • Polymer made up of monomers called nucleotides
  • These are made from 1 sugar molecule, 1 phosphate molecule (which form the backbone) and 1 of the four bases
  • These join together forming two strands (double helix)
  • The double helix is held together by weak hydrogen bonds between complimentary base pairs
43
Q

What are the complimentary base pairs?

A

Adenine and Thymine
Cytosine and Guanine 

44
Q

What is a gene?

A
  • Short section of DNA
  • Each gene codes for a particular sequence of amino acids to make a specific protein
45
Q

What is the genome?

A

The entire DNA of an organism

Biology 🌱 (9 decks)

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