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GCSE Biology OCR A > B3 > Flashcards

B3 Flashcards

1
Q

What is the function of the nervous system?

A

It allows us the make sense of our surroundings and respond to it in order to survive

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2
Q

What is the difference between sensory and motor neurones?

A

🔵Sensory neurones carry electrical impulses from receptor cells to the CNS
🔵 the cell body in the middle
🔴Motor neurones carry from the CNS to the effectors.
🔴cell body on one end

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3
Q

What is a stimulus?

A

The change in environment

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4
Q

What is a receptor?

A

A group of cells that detect the stimulus

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5
Q

What is an effector?

A

Glands or muscles where the response occurs

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6
Q

What is the CNS?

A

Central nervous system, made of delicate nervous tissue.
*Is the brain &spinal cord
Protected by the skull and vertebral

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7
Q

How does the nervous system produce a co ordinated response?

A
  1. Stimuli is received from receptors which convert it into an electrical impulse
  2. The ins pulse travels along sensory neurones to the brain and then spinal chord
  3. The information is processed and a response is sent as an electrical impulse along the motor neurones
  4. Effectors carry out the response
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8
Q

How is a co-ordinated collective response carried out to one stimulus ?

A

A series of impulses are sent out to different parts of the body producing a collective response

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9
Q

What is a reflex action?

A

A subconscious response to dangerous stimuli

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10
Q

What are some examples of reflex actions and why does the body do to respond ?

A

🔷sand blowing into eyes, eyelids make you blink
🔷bright sunshine, pupil contracts making it smaller so less light enters the eye
🔷cutting your hand on glass
🔷exposure to stressful situations , adrenaline is releases to increase heart rate

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11
Q

How is a reflex action different to a voluntary action?

A

A reflex action does not go through the conscious portion of the brain to save time. Instead just goes to spinal chord

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12
Q

Describe the cornea :

A

Transparent coating on the front of the eye.

Protecting the eye and refracting light entering the body

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13
Q

Describe the pupil :

A

Central hole in the iris

Black thing Allows light to enter the eye

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14
Q

Describe the iris :

A

Coloured part of the eye that does not let light through.

Controls how much light enters the eye by contracting or relaxing

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15
Q

Describe the Lens:

A

A transparent biconvex lens

Focuses light onto the retina

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16
Q

Describe the ciliary body:

A

Ring of muscle tissue which alters the shape of the lens

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17
Q

Describe the suspension ligaments

A

Hold up the lens and connect then to the ciliary muscle

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18
Q

Describe the retina

A

The ‘back wall’ - light sensitive which contained rods and comes detecting light

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19
Q

What is the optic nerve

A

Carries impulses between the eye and the brain

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20
Q

What is short sightedness?

A

🟡Can see near but not far objects.
🟡The lens focuses the light IN FRONT of the retina/ eyeball too long
🟡This is corrected by concave lenses

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21
Q

What is long sightedness?

A

🟡Can see far object but not near
🟡The lens focuses the image BEHIND the retina/ eyeball too short
🟡Treated by convex lenses

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22
Q

What is colourblindness?

A

🟡inability to tell the difference between two colours
🟡lack of /defects in receptors in retina
🟡is inherited

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23
Q

What are Rods?

A

A photoreceptor which respond to light , allowing to see in different levels of light

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24
Q

What are Cones?

A

A photoreceptor which responds to different colours

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25
Q

What is the function of the brain?

A

🧠processes all info from receptors (nervous system) and the hormonal system
🧠 coordinates a response

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26
Q

What is the cerebrum?

A

Controls learning, memory,personality and conscious thought.
💡largest part of the brain at the top of the skull
💡usually grey

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27
Q

What is cerebellum?

A

Co- originates voluntary body movements and helps with balance & posture
💡scrunched up leaf shape

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28
Q

What is the medulla?

A

Controls heart rate and breathing rate

💡fat belly in middle

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29
Q

What is the hypothalamus?

A

Regulates water and temperature balance

💡closest to the medulla and right under the circle thing

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30
Q

What is the pituitary gland?

A

Stores and releases many hormones

💡other scrunch in line with hypothalamus but further left

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31
Q

Why are there limitations in investing and treating brain damage?

A

👩🏻‍⚕️unethical to ask people who aren’t in the right state
👩🏻‍⚕️CNS cells don’t have the ability to regenerate/repair
👩🏻‍⚕️don’t know a lot about the brain already
👩🏻‍⚕️X-rays(CT scans) causes risk of cancer

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32
Q

What is the PNS?

A

Peripheral nervous system

The neurones that connects the CNS to the rest of the body

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33
Q

What are some examples of damage to nervous tissue?

A

🔸injury
🔸damage
🔸disease
🔸Genetic condition - Huntington’s disease
Can no longer carry impulses to & from CNS

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34
Q

Why is it hard for people to repair the nervous system?

A

CNS-
Spinal chord :very hard to identify and repair damage to an individual nerve fibre without damaging other’s
Brain:difficult to diagnose
-

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35
Q

What is the function of a hormone?

A

Chemical messengers that are secreted by endocrine glands carry messages through your blood to organs/skin/muscle

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36
Q

How does a synapse work?

A
  1. Electrical current at the end turns to chemical
  2. Diffuses over the gap to the next one
  3. Turned back into an electrical impulse
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37
Q

What happens to the pupil in different light intensity’s ?

A

High intensity = small pupil to stop light getting in

Low intensity =large pupil (dilation)

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38
Q

What is a thyroid gland?

A

Found in neck and produces thyroxine- regulates the rate of metabolism. Basically how much energy your body uses

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39
Q

What is the adrenal gland?

A

Top of kidneys , produces adrenaline- response to flight or flight : increases Herat rate, increases breathing rate( ATP via respiration)
Basically being ready to run

40
Q

What is the pancreas?

A

Stomach

Produces insulin

41
Q

What do ovaries do?

A

Produce oestrogen and progesterone

42
Q

What do the testes do?

A

Produce testosterone

43
Q

What do the hypothalamus and pituitary gland do?

A

Produce hormones that regulate the production of other hormones

44
Q

What are the differences between the nervous system and the endocrine system?

A

⚫️nerves travel faster
⚫️nerves travel along axons rather than in the bloodstream
⚫️a hormone is long acting
⚫️a neurone has precise area as opposed to a larger area

45
Q

How do hormones travel?

A
  1. Glands secret hormones into bloodstream
  2. Bind to a receptor of target organ
  3. Trigger certain changes or the cell
46
Q

Describe negative feedback (Thyroxine)

A
  1. Pituitary detects levels of thyroxine
  2. Secrets thyroid stimulating hormone
  3. which tells the thyroid gland to secrete more/less thyroxine
47
Q

What is the purpose of a negative feedback system ?

A

It allows systems to self stabilise which is a vital control mechanism for homeostasis

48
Q

FSH

A

Follicle stimulating hormone- matures eggs in the ovary
Produces by the pituitary gland
🔺increases Oestrogen
🔺is inhibited by oestrogen and progesterone
Increases on day 14 but only a small spike

49
Q

Progesterone

A 
Maintains the lining of the uterus 
Secreted by ovary 
🔺decreases FSH
🔺decreases LH
Increases between day 14-28 and then brought back down
50
Q

Oestrogen

A 
Secreted by pituitary 
Helps build the lining if the uterus 
🔺increases LH
🔺decreases FSH
Rises between day 4-14 and the is brought back down to normal level
51
Q

LH

A

Luetenising hormone
Secreted from the pituitary gland
Releases eggs from the ovary

Only increases on day 14 for ovulation

52
Q

Describe the main stages of the menstrual cycle:

A
  1. First 4 days the thickness of the lining is broken down completely-due to menstruation
  2. From then till day 14 , the lining is built up to prepare for the fertilised egg
  3. Day 14 is when ovulation occurs, egg is releases from the ovary
  4. For the next 28 days the lining is maintained
    … however if the egg was fertilised the lining would continue to be maintained as the egg would implant itself there as it develops to a foetus
53
Q

What are some examples of hormonal contraception?

A

(Disrupt the normal female reproductive cycle)
💊 The Pill
Contains oestrogen and progesterone which inhibits the production of FSH- so eggs don’t mature
99% effective
Side effects: mood swings/weight gain

🗜 hormonal coil
Slow release of progesterone which prevent ovaries from releasing egg, thickens mucus so sperm cannot swim
Don’t need to take everyday

54
Q

What are some non-hormonal contraceptives?

A

Condom
Easy and no STDs

Vasectomy
Sperm tubes are cut
But irreversible

The coil
Copper kills sperm
Lasts up to 20 years
Risks of ectopic pregnancy

55
Q

Why might someone be infertile?

A

❣️blocked some ducts
❣️not enough sperm or mature eggs
❣️failure of ovaries to release an egg (lack of FSH)

56
Q

Describe how IVF can be used to treat infertility:

A
  1. Mother gives FSH & LH to stimulate eggs to mature
  2. Eggs are collected in a Petri dish and fertilised by father’s sperm in a lab
  3. These fertilised eggs develop into embryos
  4. Embryos are then implanted back into mother’s uterus
57
Q

What are some of the issues around IVF

A

✅allows people to have a baby
✅allows older people
❌not natural
❌results in multiple births which is dangerous ❌expensive

58
Q

How do hormones treat infertility?

A

FSH is taken which stimulates eggs to mature, triggering oestrogen

59
Q

What is phototropism?

A

Growing towards the light , a stem does this to photosynthesis more

60
Q

What is gravitropism/geotropism ?

A

Growing the same direction as gravity, this is important for the roots to provide anchorage.

61
Q

What is the role of auxin ?

A

It’s a plant hormone, the imbalance of it triggers a stimulus. This creates an unequal growth rate causing bending.
It stimulates shoot 🌱cells to grow more and inhibits the growth of roots⛓

62
Q

Auxin in roots me shoots geotropism &phototropism

A

Gravity

  1. Auxin in down due to gravity
  2. Grows on the side with no auxins, bends down (ROOTS)
  3. In plants it grows on the side with auxins making it grow up

Phototropism:

In shoots:

  1. Auxins go where it is shady
  2. Grow in the shady side making it bend to the sunny side
63
Q

What happens when the auxin distribution is equal?

A

If grows straight in that direction

64
Q

What are commercial uses of auxins?

A

Cause growth by cell elongation

🔪🌱weed killers:
Causes rapid cell growth , cannot keep up and dies

🌫root powder
Take a cutting from plant, put in possession, grows roots

65
Q

What are Gibberellins and their commercial uses?

A

Stimulate seed germination , flowering &shedding of leaves

Making more seeds:🪴
Flowering: can grow in any conditions🌺🌷🌸
Increasing fruit size

66
Q

What is ethene and their commercial uses?

A

Used in cell division and ripening of fruits

Food picked when not ripe, but can be ripened after the journey to prevent damage and bruises🍏🍎🍌🍉🍐

67
Q

What is the importance of maintaining a constant internal environment?

A

Homeostasis is required for optimum conditions for enzymes as well as cell functions. If not kept to optimum temperature then enzymes cannot speed up reactions (respiration)at a fast enough rate for the body’s needs…DEATH

68
Q

What is homeostasis?

A

The maintenance of constant internal environment despite hangers in internal and external conditions

69
Q

What does your body do when it gets too hot?

A

🟡hairs fall, to stop insulation
🟡vasodilation: blood vessels closer to the surface of the skin by dilating. Blood flows closer to surface so more energy is transferred to surroundings
🟡sweat evaporates, transferring energy from your skin to the environment

70
Q

What does your body do when it gets too cold?

A

🟡hairs stand on end to trap a layer of insulation to keep you warm
🟡vasoconstriction: blood vessels near the skin narrow, less blood flows near the surface, less energy is transferred to the surroundings
🟡shivering, respiration occurs for muscles transferring energy to the body

71
Q

What temperature must the body be kept at all times?

A

37 degrees

72
Q

Why do blood sugar levels change throughout the day?

A

Food and physical activity choices

73
Q

How does insulin maintain the blood glucose levels?

A
  1. Pancreas detects a rise in blood glucose concentration
  2. Secrets insulin high binds to receptors in target organs (normally liver/muscle)
  3. forms glycogen - a store of glucose
74
Q

What is the difference between type 1 and type 2 diabetes?

A

1️⃣pancreas produces little to no insulin
1️⃣genetic
1️⃣can use insulin injections
1️⃣regular exercise and eating simple carbohydrates 2️⃣body is resistant to insulin
2️⃣caused by diet
2️⃣loosing weight/exercising/healthy diet
2️⃣drugs

75
Q

Must must water levels in the body remain constant?

A

If too much water is present in blood cells they will burst (lysis)
Too little water will cause them to shrink

76
Q

How does the body produce urine?

A
  1. Blood is transported to the kidney through the renal artery
  2. Blood is filtered at high pressure , removing water, glucose, urea and salts
  3. Then the kidney selectively reabsorbs any useful materials such as glucose, salt, water
  4. After being purifies the blood returns through the renal vein
77
Q

What is the ureter?

A

Tube through which the urine passes from the kidney to the bladder

78
Q

What is the urethra?

A

End of bladder where the urine passes out of the body

79
Q

How does the body maintain water balance by varying urine concentration?

A

Kidneys balance the amount taken in vs the amount taken out. If not a lot of water has been consumed the urine will not have a lot of water and will therefore be concentrated and yellow. A lot of water= diluted urine

80
Q

What is the cortex? (Kidney)

A

The outer part of the kidney

81
Q

What is the medulla (kidney)?

A

The inside part of the kidney

82
Q

What is the glomerulus and what does it do?

A

First stage

Tiny small thin walls allowing smaller molecules to pass into the tubules,

83
Q

What does bowman’s capsule do?

A 
Surrounds the glomerulus.
The urine (waste ) is filtered into it as is carry’s it overs to the nephrons
84
Q

What happens in the tubules and the loop of Henley?

A 
Selective reabsorption , where the body takes back what it needs:
🟣 All sugar(first coil)
Loop of Henley
🟣some water
🟣some salt
85
Q

What happens at the collecting duct?

A

The urine is taken down to the ureters

86
Q

How does ADH determine the amount of water that is reabsorbed?

A

Anti-diuretic hormone
🟤released by pituitary and goes to kidney tubules
🟤increases the permeability of tubules water
🟤so more water back into bloodstream
🟤more yellow/ concentrated urine

87
Q

How does the body respond to dehydration?

A

Salt loss and water loss,makes thirst signal, more water diluted the salts in out blood

88
Q

How does the body respond to too much water?

A

If too much consumed as kidneys cannot cope , then the cells burst (lysis) due to osmosis. DEATH

89
Q

Why are sports drinks required?

A

When exercising you loose sugar, water and salts. To make sure your body is working in the most efficient way.

90
Q

What do isotonic drinks contain?

A

The same level of water and sugar as normal

91
Q

What do hypertonic drinks contain

A

High levels of glucose and salts than normal

92
Q

What do hypotonic drinks contain?

A

Low levels of glucose, salts than normal

93
Q

How do you focus on nearby objects?

A

Nearby = (contracts )lens becomes fatter, more convex

The ciliary body contracts, the suspension ligaments slack (loosen).

94
Q

What part of the neuron carries impulses away from the cell body?

A

Axon

95
Q

What structures of the neuron help speed up the transition of impulses?

A

🟣length- not as many connections doesn’t slow it down

🟣fatty sheath - electrical insulator, speeding it up

GCSE Biology OCR A (7 decks)

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