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GCSE Edexcel Biology > Cells and Control > Flashcards

Cells and Control Flashcards

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1
Q

How do you do a scientific drawing?

A

Use a sharp pencil
Use clear, unbroken lines
Draw outlines of the main features - no shading
Take up at least half of the space
Keep parts in proportion
Label important features with straight, uncrossing lines
Include a scale and the magnification

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2
Q

What is a chromosome?

A

They are coiled up lengths of DNA molecules that contain genetic material. Cells normally have two copies of each chromosome, making them ‘diploid’ cells. One chromosome comes from the organism’s ‘mother’; one comes from its ‘father’.

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3
Q

What is mitosis used for?

A

Growth or repairing damaged cells.

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4
Q

What is mitosis?

A

A type of cell division and part of the cell cycle resulting in two daughter cells with identical chromosomes to the parent cell

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5
Q

What is interphase?

A

The time when a cell is not dividing, where chromosomes are uncoiled. The cell replicates all of its subcellular structures and DNA in this period

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6
Q

What are the four stages of mitosis?

A

Prophase, metaphase, anaphase, telophase

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7
Q

What is prophase?

A

The first stage of mitosis, where chromosomes condense, getting shorter and fatter. The nucleus membrane breaks down and chromosomes lie free

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8
Q

What is metaphase?

A

The second stage of mitosis, where the chromosomes line up at the centre of the cell

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9
Q

What is anaphase?

A

The third stage of mitosis, where cell fibres pull the chromosomes apart. The two arms of each chromosome go to opposite ends of the cell

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10
Q

What is telophase?

A

The fourth stage of mitosis, where membranes form around each of the sets of chromosomes. The nucleus has divided

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11
Q

What is cytokinesis?

A

When the cytoplasm and cell membrane divide to form two separate cells

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12
Q

How do plants and animals grow and develop?

A

Cell differentiation - cells becoming more specialised
Cell division - by mitosis
(In plants) Cell elongation - plant cells expanding

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13
Q

What is cancer?

A

When a change in one of the genes controlling cell division causes a cell to start dividing uncontrollably. This can result in a mass of abnormal cells called a tumour. If it invades and destroys surrounding tissue it is called cancer

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14
Q

What are stem cells?

A

Undifferentiated cells that can divide by mitosis to become new cells, which then differentiate

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15
Q

What is the difference between embryonic and adult stem cells?

A

Embryonic stem cells are found in early human embryos. They have the potential to divide and produce any type of cell.
Adult stem cells are found only in some places, like bone marrow. They can only produce some types of cells so they are not as versatile.

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16
Q

What are meristems?

A

A plant tissue found at the tips and roots of shoots (parts of a plant that are growing). They are the only cells in plants that divide by mitosis. They produce unspecialised cells that can divide and differentiate into any type of cell.

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17
Q

How are stem cells used in medicine?

A

Adult stem cells can cure some diseases, such as sickle cell anaemia with a bone marrow transplant. Embryonic stem cells are being experimented on to see if they could produce any type of cell

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18
Q

What are the potential risks with stem cells?

A

Tumour development - stem cells divide very quickly
Disease transmission - unnoticed viruses could be passed on in stem cells
Rejection - they could be recognised as foreign and trigger an immune response

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19
Q

What are growth charts?

A

Charts that show a number of percentiles of growth

20
Q

What does the cerebrum do?

A

It is the largest part of the brain, divided into two cerebral hemispheres that control the opposite sides of the body. It controls higher function, including movement, intelligence, memory, language, and vision

21
Q

What does the cerebellum do?

A

It is responsible for muscle coordination and balance

22
Q

What does the medulla oblongata?

A

It controls unconscious activities like breathing and heart rate

23
Q

What are CT scans?

A

A scan using X-rays to produce and image of the brain. It shows the main structures but not their function. If it shows a diseased or damaged brain structure and the patient has lost some function, the function of a part of the brain can be worked out.

24
Q

What are PET scans?

A

A scan using radioactive chemicals to show which parts of the brain are active when the person is inside the scanner. They are very detailed and can show the brain’s structure and function in real time. They can show if areas in the brain are unusually inactive or active, show they can study disorders changing the brain’s activity

25
Q

Why can it be difficult to treat problems in the central nervous system?

A

It is hard to repair damage - neurones do not readily repair themselves and there is not yet a way to repair it
It is hard to access parts of the CNS
It can lead to permanent damage - mistakes can mean the CNS is damaged further

26
Q

What are the parts of the nervous system?

A

Brain
Spinal cord
Nerves

27
Q

What does the nervous system enable you to do?

A

Control your body

Get feedback about the world

28
Q

How does the CNS coordinate responses?

A

Sensory receptors detect a stimulus. Different receptors detect different stimuli. When a stimulus is detected information is converted to a nervous impulse and sent to the CNS. The CNS coordinates a response. Impulses travel through the CNS along relay neurones. It sends info to an effector along a motor neurone.

29
Q

How do neurones transmit information?

A

They have cell bodies with a nucleus. The cell body has extensions that connect to other neurones. Some axons are insulated with a myelin sheath, speeding up the impulse. They are connected by synapses.

30
Q

What is the structure and function of a sensory neurone?

A

They carry impulses from receptors to relay neurones. One long dendron carries nerve impulses to the cell body. One short axon carries nerve impulses from the cell body to the CNS.

31
Q

What is the structure and function of a relay neurone?

A

They carry nerve impulses from sensory neurones to motor neurones. Many short dendrites carry nerve impulses to the cell body. An axon carries nerve impulses from the cell body to motor neurones.

32
Q

What is the structure and function of a motor neurone?

A

They carry nerve impulses from relay neurones to effector cells. Many short dendrites carry nerve impulses to the cell body. One long axon carries nerve impulses from the cell body to effector cells.

33
Q

What are synapses?

A

The connection between two neurones. The signal is transferred by chemicals called neurotransmitters which diffuse across the gap. They then set off a new electrical signal in the next neurone. It is slower than transmission in one neurone, as diffusion takes time

34
Q

How do reflexes work?

A

They are automatic, rapid responses to stimuli. There is a reflex arc: stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response. It does not involve the conscious brain so it is quicker than normal responses

35
Q

What does the cornea do?

A

Refracts light into the eye

36
Q

What does the iris do?

A

Controls how much light enters the pupil

37
Q

What does the lens do?

A

Refracts light, focusing it onto the retina

38
Q

What does the retina do?

A

Senses light as it is covered in receptor cells called rods and cones

39
Q

What does the optic nerve do?

A

Carries electrical impulses from receptors to the brain

40
Q

What does the pupil do?

A

Allows light to pass through as it enters the eye

41
Q

What is the pupil reflex?

A

In dark conditions the pupil dilates to allow for more light. In light conditions it constricts to prevent retina damage.
To constrict the pupil the circular muscles contract and the radial muscles relax
To dilate the pupil the circular muscles relax and the radial muscles contract

42
Q

What are rods and cones?

A

Found in the retina
Rods are sensitive to dim light but not colour
Cones are sensitive to colours but not good in dim light

43
Q

How and why does the lens change shape?

A

For light that is far away the lens needs to be flatter so less refraction happens. Ciliary muscles relax and suspensory ligaments become tense.
For light that is near the lens needs to be rounder so more refraction happens. Ciliary muscles contract and suspensory ligaments become slack.

44
Q

What is long sightedness caused by? How is it treated?

A

It occurs when the lens is the wrong shape and does not bend the light enough or when the eyeball is too short. Light from near objects is focussed behind the retina. Glasses with a convex lens fixes it.

45
Q

What is short sightedness caused by? How is it treated?

A

It occurs when the lens is the wrong shape and bends light too much or when the eyeball is too long. Light from distant objects is focussed in front of the retina. Glasses with a concave lens fixes it.

46
Q

What is colour blindness caused by? How is it treated?

A

Cones in the retina are not working properly so you cannot tell the difference between certain colours. There is no cure as cone cells cannot be replaced.

47
Q

What are cataracts caused by? How is it treated?

A

It is a cloudy patch on the lens, which stops light from being able to enter the eye normally. This causes blurred vision. Sometimes colours look less vivid and it is difficult to see in bright light. It can be treated by replacing the lens with an artificial one.

GCSE Edexcel Biology (9 decks)

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