SB2 Flashcards
Cells and Control
1
Q
What is a gene?
A
A short section of DNA
2
Q
What is a chromosome?
A
A thin strands of DNA
3
Q
What is a diploid number of cells
A
The full amount of chromosomes within a cell
4
Q
What is a haploid number of cells
A
Half of the amount of chromosomes within a cell
5
Q
What is the diploid and haploid number of cells within humans
A
Diploid: 46
Haploid: 23
6
Q
What are the three stages of the cell cycle?
A
- Interphase
- Mitosis
- Cytokinesis
7
Q
What happens in Interphase?
A
The cell grows, replicates its DNA and prepares for cell division
8
Q
A
9
Q
What happens in Cytokinesis
A
Cell membrane pinches to form two indentical daughter cells
10
Q
What is Mitosis required for?
A
- Growth: producing new cells
- Repair: replace damaged/dead cells
- Asexual reproduction
11
Q
What are the 4 stages of Mitosis
A
- Prophase
- Metaphase
- Anaphase
- Telophase
12
Q
What happens in Prophase
A
- DNA condenses
- Chromosomes become visible
- Nuclear membrane breaks down
13
Q
What happens in Metaphase
A
- Chromosomes line up at the equator of the cell
14
Q
What happens in Anaphase
A
Chromatids are pulled to opposite poles of the cell
15
Q
What happens in Telophase?
A
Two new nuclei form at the end of the cell
16
Q
How does cancer occur
A
By mitosis. Uncontrolled cell growth and division and can lead to tumour growth.
17
Q
What are the two types of tumours?
A
- Benign
- Malignant
18
Q
What are Benign tumours?
A
- Abnormal cell growth that is not cancer.
- Does not invade nearby tissue or spread to other parts of the body.
19
Q
What are Malignant tumours
A
- Cancerous cells that grow uncontrollably and spread locally and/or to distant sites.
- Disrupt the functions of organs
20
Q
How does growth occur in humans
A
- Cell division
- Cell differentiation
21
Q
How does growth occur in plants
A
- Cell division
- Cell elongation
- Cell differentiation
22
Q
What is cell differentiation?
A
the process by which cells become specialized to perform specific functions in an organism
23
Q
What is cell elongation in plants?
A
Where hormones (such as auxins) cause cells to grow longer in response to stimuli
24
Q
What are percentile charts
A
measurements that show where a child is compared with other kids
25
What issues can be flagged up on percentile charts
1. Malnutrition
2. Obesity
3. Inconsistences in growth
4. Sudden changes in trends
26
What does is mean if a baby is on the 25th percentile for mass
They are lighter than 75% of children their age and heavier than 25%
27
What is a stem cell?
an undifferentiated cell that can turn into a specialised cell
28
What are embryonic stem cells
Cells from early embryos that can develop into any cell type in the human body.
29
What are adult stem cells
Cells found in the bone marrorw that can only differentiate into blood cells
30
Where are meristems found
In roots and shoots
31
What is the function of meristems
1. Can differentiate into any type of plant
2. Can be used to make clones of plants
32
What is therapeutic cloning
to use a person's DNA to clone one of their organs for use in transplanting
33
What is the positives of stem cells
Can be used to repair damaged and diseased body parts
34
What are the the negatives of stem cells
1. Risk of rejection
2. Removal of stem cells can cause destruction in the embryo
3. Could cause uncontrolled cell division which can lead to tumours
35
What is the function of the Cerebrum
1- consciousness
2- memory
3- intelligence
4- visual and sensory processing
36
What is the function of the cerebellum
1- controls fine movements of the muscles
2- responsible for co-ordination
37
What is the function of the medulla oblongata
Responsible for automatic bodily functions i.e breathing, digestion, swallowing and sneezing
38
How do CT scans work
1. X-ray radiation is fired at the brain from various angles
2. Produces a 3D image of the brain
39
What is the main purpose of CT scans
Exanimating bleeding to the skull and damage to brain structures
40
How do PET scans work
1- A radioactive tracer is injected into the blood before scanning
2- Tracer builds in in areas with a higher blood flow
3- Will be highlighted on the resulting scan
41
What are PET scans used for
Identifying cancerous tumours (as the use more blood than normal tissue)
42
Why is it difficult to investigate the brain
1- It's complex and delicate
2- It's easy damaged and any damage could alter motor or personality permantely
43
How does the Central nervous system work
1- Receptor cells convert a stimulus into electrical impulse
2- Impulse travels along sensory neurons to the CNS
3- Impulse is sent across motor neurons to effectors
4- Effectors carry out a response
44
What is a reflex
An electrical response that bypasses the conscious areas of the brain
45
Describe the 5 steps of a reflex arc
1- A stimulus is detected by receptors
2- Impulses are sent along a sensory neuron
3- the impulse bypasses CNS to a relay neuron
4- Impulses are sent along a motor neuron
5- The impulse reaches an effector and an appropriate response occurs
46
What are two examples of reflex arcs
1- Pupils getting smaller to in bright light
2- Moving your hand from a hot surface
47
What's a synapse
The gap between two neurons
48
How do synapses assist in the transmission of electrical impulses
1- Impulse reaches the end of the first neuron neurotransmitters are realised into the synapse
2- This neurotransmitter diffuses across the synapse
3- Once the neurotransmitter reaches the second neuron it triggers the impulse to begin again in the next neuron
49
Why are some nerves myelinated
Acts as an insulator which speeds up the speed of electrical impulses
50
What is the function of the cornea?
A transparent lens that refracts light as it enters the eye
51
What if the function of the lens
Transparent disc that adjusts width to focus light onto the retina
52
What is the function of the iris
Controls how much light enters the pupil
53
What is the the difference between rod and cones cells
Rods = detect light intensity
Cones = detect colour
54
What is the function of the Retina
Contains light receptor cells
55
What is the function of the pupil
Hole that allows light to enter the eye
56
What is the process of accommodation within the eye
The process of where the eye adjusts to be able to see objects at different distances
57
What is the ciliary muscle
A ring of muscle that contracts and relaxes to change the shape of the lens
58
What are suspensory ligaments
Ligaments connecting the ciliary muscles to the lens
59
How does the eye adjust to focus on near objects
1. Ciliary muscles contract
2. Suspensory ligaments loosen
3. The lens is then thicker and move curved refracting more light
60
How does the eye adjust to focus on more distant objects
1- Ciliary muscles relax
2- Suspensory ligaments tighten
3- Lens are made thinner; light is refracted less
61
What is short sightedness called and how is it caused
myopia: when the lens are too curved light is refracted too much and the focal point falls in front of the retina
62
What is long sightedness called and how is it caused
Hyperopia:
• lens is too flat
• eyeball is too small
• light can't be refracted enough and focal point falls behind the retina
63
What are cataracts
Clouding of the lens in the eye restricting vision
64
What is colour-blindness
The inability to see certain colours do to the lack of cone cells in the retina
65
How can myopia (short-sightedness) be treated
Concave lenses - allow light to be spread out to reach the retina
66
How can hyperopia (long-sightedness) be treated
Convex lenses - bring rays of light together to reach the retina
67
How does the eye respond in bright rooms
1- Photoreceptors detect light change
2- Radial muscles relax
3- Pupil constricts
4- Less light enters the eye
68
How can cataracts be treated
Replacing the cloudy lens with an artificial one
69
How does the eye adjust in dim lighting
1- Photoreceptors detect change
2- Radial muscles contract
3- Pupil dilates
4- More light enters the eye
70
How is the growth of babies monitored
1. Mass
2. Length
3. Head circumference
