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biology > Topic 2 Cells > Flashcards

Topic 2 Cells Flashcards

1
Q

What are chromosomes

A

Long strands of DNA

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2
Q

What is a gene

A

Short section of DNA that codes for a protein and controls a characteristic

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3
Q

What is step 1 of cell cycle and what does it do

A

Interphase:
new sub-cellular structures made
DNA replicates

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4
Q

Step 2 of cell cycle what does it do

A

Prophase
- DNA condenses into chromosomes
- nuclear membrane breaks down

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5
Q

Stage 3 of cell cycle and what does it do

A

Chromosomes line up across the equator of the cell
Spindle fibres form and attach to the chromosomes

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6
Q

Stage 4 of cell cycle what does it do

A

Anaphase
-spindle fibres contract and pull apart the chromosomes to opposite sides of the cell/poles

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7
Q

Stage 5 of cell cycle

A

Telophase
-nuclear membrane forms around two sets of chromosomes
-two nuclei formed

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8
Q

Stage 6 cell cycle

A

Cytokinesis
Cytoplasm splits
Cell membrane reforms
Two, genetically identical diploid (46 chromosomes) daughter cells

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9
Q

How does growth occur in animals

A

Via cell division and differentiation
All cells differentiate at an early stage and then lose the ability

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10
Q

How does growth occur in plants

A

Elongation - controlled by auxins
Cells retain ability to differentiate throughout life

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11
Q

How is cancer caused

A

Result of mutations in cells that lead to uncontrolled cell division.
The group of cells caused by this is called a tumour.

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12
Q

How percentile works

A

Baby born at 25 percentile is heavier than 75% of babies
Baby born at 75 percentile is heavier than 25% of babies

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13
Q

What are embryonic stem cells

A

Form when an egg and sperm cell fuse to form a zygote
Differentiate into any type of cell
Scientists can clone these cells and differentiate them into almost any cell
This could be used to make insulin producing cells for people with diabetes

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14
Q

What are adult stem cells

A

If found in bone marrow they can form many types of cells including blood cells

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15
Q

What are meristems in plants

A

Found in root and shoot tips
Differentiate into any type of plant, never lose ability
Can be used to make any clones of the plant: saves plants from extinction or can take a parent plant’s desirable features e.g. disease resistance

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16
Q

What is therapeutic cloning

A

An embryo being produced with the exact same genes as the patient
Can use the embryo for embryonic stem cells
Embryo could grow into cells the patient needs
Would not be rejected due to same genetic makeup

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17
Q

Three benefits of stem cells

A

Could be used to replace damaged or diseased body parts
Unwanted embryos from fertility clinics that would’ve been discarded can be used
Research into the process of differentiation

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18
Q

Four Problems with stem cells

A

Do not completely understand process of differentiation so it is hard to control stem cells to form cells we desire

Removal of stem cells result in destruction of embryo - religious issue

Money and time could be spent on other areas

If growing stem cells cell has virus or infection, it can be transferred to individual

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19
Q

CNS meaning

A

Central Nervous System

20
Q

What’s the cerebrum for (the big part of the brain)

A

Consciousness, memory, visual and sensory processing, intelligence

21
Q

What is the cerebellum (lump like structure at the bottom of the brain)

A

Controls fine movement of muscles and co-ordination

22
Q

What is the medulla oblongata

A

Small elongated structure found in the brainstem at the base of the brain
Controls autonomic functions breathing, digestion, swallowing and sneezing

23
Q

Why can you not cut open the skull and physically examine the brain

A

It is highly invasive

24
Q

How do CT scans work

A

Fire x-ray radiation at the brain from several different angles to generate a 3D image of the brain

Useful for examining bleeding within the skull and damage to brain structures

Not recommended for pregnant women and children due to higher doses of radiation

25
How do PET scans work
A radioactive tracer is injected into the blood before the scan. Areas where the tracer builds up (which will be areas with greater blood flow) will be highlighted more brightly on the results. This is useful for identifying cancerous tumours as these use more blood than normal tissue and will appear in areas of poor blood flow
26
Why is treating and identifying brain damage and disease difficult
Complex and delicate Easily damaged Drugs given can’t always reach the brain due to membranes surrounding it Not fully understood which part of brain does what
27
Why are cancerous tumours in the brain dangerous
The tumours can push against other structures and blood vessels in the brain, restricting their function. They can also be buried deep in the brain or spinal cord which makes it difficult to remove
28
Nervous system function order
Receptor cells convert a stimulus into an electrical impulse Electrical impulse travels along cells called sensory neurons to the CNS In the CNS, the impulses are passed on to a relay neurone This links to a motor neurone where the impulses travel along until they reach the effector The effector is what carries out the response (the effector mah be a muscle or gland)
29
Explain the order of the reflex arc
Stimulus is detected by a receptor Sensory neurone sends electrical impulses to the spinal cord Electrical impulse is passed to a relay neurone in the spinal cord (part of the CS) Relay neurone synapses with a motor neurone Motor neurone carries an impulse to the effector When stimulated by the motor neurone, response occurs Stimulus Receptor Sensory Spinal cord Relay Synapse Motor Effector Response
30
Explain the role of the synapse
Electrical impulse reaches the end of the first neuron Neurotransmitter is released into the synapse. The neurotransmitter diffuses across the synapse It reaches the second neurone and triggers the impulse to begin again in the next neurone Different neurotransmitters have different effects on the frequency and speed of the impulse in the second neurone
31
What does the myelin sheath do
Speeds up nerve transmission
32
What is the retina
Layer of light sensitive cells found at the back of the eye
33
What does the retina contain
Rod cells: Sensitive to light cone cells: Colour vision
34
What is the cornea
See through layer at the front of the eye Allows light through and the curved surface bends and focuses light onto the retina
35
What is the iris
Muscles that surround the pupil They contract or relax to alter the size of the pupil
36
What does the iris do in dim light
the circular muscles relax and the radial muscles contract to make the pupil larger so more light can enter to create a better image.
37
What does the iris do in bright light
the circular muscles contract and radial muscles relax to make the pupil smaller - avoiding damage to the retina.
38
What do the ciliary muscles and suspensoirs ligaments do
Holds the lens in place Controls it shape and allows us to focus on objects nearer or further away
39
What are the lens
Transparent, curved surface on the front of the eye Reflects light onto retina
40
How the eye focuses on a near object
Ciliary muscles contract Suspensory ligaments loosen If lens is thicker and more curved, this refracts the light
41
How to focus on a distant object
Ciliary muscles relax Suspensoirs ligaments tighten Lens becomes thinner-light is refracted less
42
Why does myopia happen and treatment
Lens too curved so distant objects blurry Concave lens to spread out light
43
How does hyperopia happen
Lens is too flat so can’t refract light enough Convex lens to bring rays together
44
What’s cataracts
Clouding if the lens of the eye Fixed by replacing lens in surgery
45
What’s colour blindness and how treated
Not enough cone cells in retina

biology (9 decks)

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