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GCSE Biology > Homeostasis And Response > Flashcards

Homeostasis And Response Flashcards

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1
Q

What is homeostasis?

A

Homeostasis is the maintence of a constant internal environment in order to maintain optimum conditions for enzyme and cellular function

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2
Q

Give examples of conditions maintained by homeostasis in the body

A

blood glucose concentration, body temperature and water levels

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3
Q

What two types of responses are used in body control systems?

A

nervous and chemical

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4
Q

What three components do all control systems have?

A

Receptors, coordination centres and effectors

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5
Q

What is the function of a receptor?

A

Receptors detect changes in the environment (stimuli).

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6
Q

What is the function of a coordination centre?

A

Coordination centres obtain and process information from receptors.

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7
Q

What is the function of an effector?

A

Effectors (muscles or glands) bring about responses to stimuli.

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8
Q

What is the function of the nervous system?

A

The nervous system allows the body to react to its surroundings and coordinate an appropriate response

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9
Q

How does a stimulus lead to a response being carried out by the body?

A

● Stimulus is converted into an electrical impulse by the receptors.
● The electrical impulse passes along sensory neurones to the central nervous system (CNS).
● The CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector, which carries out the response.

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10
Q

What sequence of events describes how the nervous system works?

A

Stimulus → receptor → coordinator → effector → response

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11
Q

What is a reflex action?

A

A reflex action is an automatic and rapid response which does not involve any conscious input from the brain.

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12
Q

Why are reflex actions important?

A

Reflex actions aid survival by preventing harm to the body.

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13
Q

Describe how a reflex action occurs via a reflex arc

A

● The stimulus is detected by a receptor.
● An electrical impulse passes along a sensory neurone to the spinal cord (part of the CNS).
● At a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap and stimulates a new impulse which passes along the relay neurone.
● The same process occurs at a synapse between a relay neurone and a motor neurone.
● At the effector, an appropriate response is carried out

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14
Q

What is the difference between a reflex pathways and a conscious pathway?

A

Within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord/unconscious parts of the brain (in a conscious pathway, the coordination centre is in the conscious part of the brain)

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15
Q

What is the function of the cerebral cortex?

A

Controls consciousness, intelligence, memory and language

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16
Q

What is the function of the cerebellum?

A

controls muscular coordination

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17
Q

What is the function of the medulla?

A

Controls unconscious activities like breathing and your heartbeat

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18
Q

Why is the investigation and treatment of the brain difficult?

A

● The brain is a complex and delicate organ.
● The brain is easily damaged and destroyed.
● Certain membranes prevent drugs from reaching the brain.
● The exact function of each part of the brain is not known.

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19
Q

What methods are used by scientists to determine brain function?

A

● Studying patients with brain damage
● Electrical stimulation of the brain
● MRI scans

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20
Q

What stimuli are the receptors of the eye sensitive to?

A

Light intensity and colour

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21
Q

What are the two main functions of structures found within the eye?

A

● Focusing on near or distant objects - accommodation.
● Adaptation to dim light.

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22
Q

Describe the structure and function of the retina

A

The retina is a light-sensitive layer found at the back of the eye.
Light stimulates the retinal cells, resulting in impulses being sent to the brain.

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23
Q

Describe the structure and function of the optic nerve

A

The optic nerve connects the eye and the brain. It carries impulses to the brain so that an image can be visualised.

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24
Q

Describe the structure and function of the sclera

A

The sclera is the tough outer layer of the eye which protects its internal structures.

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25
Q

Describe the structure and function of the cornea

A

The cornea is the curved transparent layer at the front of the eye. It lets light into the eye and allows light to be focused onto the retina.

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26
Q

Describe the structure and function of the iris

A

The iris is a muscle which controls the size of the pupil by contracting or relaxing. This allows the eye to adjust to bright and dim lighting

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27
Q

Describe the structure and function of the ciliary muscles and suspensory ligaments

A

The ciliary muscles (C) and suspensory ligaments (E) hold the lens in place and control its shape.

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28
Q

Describe how the iris alters the size of the pupil in both bright and dim light

A

● Bright light: circular muscles contract and radial muscles relax - makes pupil smaller to avoid retinal damage.
● Dim light: circular muscles relax and radial muscles contract - makes pupil larger so more light can enter the eye.

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29
Q

What is accommodation?

A

Accommodation is the alteration of the lens’ shape in order to focus on near or distant objects.

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30
Q

How does the eye focus on a nearby object?

A

● Ciliary muscles contract.
● Suspensory ligaments loosen.
● Lens becomes thicker and more curved - light rays are refracted strongly.

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31
Q

How does the eye focus on a far away object?

A

● Ciliary muscles relax
● Suspensory ligaments tighten
● Lens becomes thinner - light rays are refracted weakly

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32
Q

What is myopia?

A

Myopia (short-sightedness) usually occurs when the lens of the eye is too curved. As a result, light is focused in front of the retina so images appear blurry.

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33
Q

How can myopia be treated?

A

Myopia can be treated using glasses with a concave lense, which spreads out light rays so they can be focused on the retina.

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34
Q

What is hyperopia?

A

Hyperopia (long-sightedness) usually occurs when the lens of the eye is too flat. As a result, light is focused behind the retina so images appear out of focus.

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35
Q

How can hyperopia be treated?

A

Hyperopia can be treated using glasses with a convex lense, which brings the light rays together so they can be focused on the retina

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36
Q

What are the two types of contact lenses?

A

Contact lenses are lenses that are placed on the eye. There are two types:
● Hard - rigid material, last a long time, must be kept sterile.
● Soft - flexible material, last for a shorter time, more comfortable.

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37
Q

What is laser eye surgery?

A

Laser eye surgery is the use of lasers to fix visual defects in adults. To treat myopia, lasers reduce the thickness of the cornea so light is refracted less strongly. To treat hyperopia, lasers alter the curvature of the cornea so that light is refracted correctly.

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38
Q

How can replacement lenses be used to treat visual defects?

A

A replacement lens can either implanted into the eye (along with the natural lens) or it may replace the natural lens altogether. Risks of lens replacement include retinal damage, cataracts and infections.

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39
Q

What are the risks of lens replacement?

A

Risks of lens replacement include retinal damage, cataracts and infections

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40
Q

Where is body temperature controlled in the body?

A

Body temperature is controlled by the thermoregulatory centre in the hypothalamus of the brain.

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41
Q

How is temperature monitored by the body?

A

● Thermoregulatory centre has receptors sensitive to blood temperature.
● Skin has receptors sensitive to skin temperature - sends impulses to thermoregulatory centre.

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42
Q

What physiological changes occur when the body temperature is too high?

A

● Vasodilation - blood vessels near the surface of the skin dilate - more heat is radiated away.
● Sweating - evaporation of water takes away heat energy from the surface of the skin.

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43
Q

What physiological changes occur when the body temperature is too low?

A

● Vasoconstriction - blood vessels near the surface of the skin constrict - less heat radiated away.
● Shivering - respiration allows muscles to contract. It is an exothermic process, so heat energy is released.
● Sweating stops.

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44
Q

Give the name of the body’s coordination system which involves hormones

A

endocrine system

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45
Q

What is a hormone?

A

A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ, where it causes a response.

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46
Q

What type of organ secretes hormones?

A

glands

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47
Q

Which gland controls many other glands in the body?

A

pituitary gland

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48
Q

Why is the pituitary gland called the master gland?

A

It secretes a wide range of hormones, some of which may stimulate other endocrine glands.

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49
Q

What is the role of the pituitary gland in the endocrine system?

A

● Secretes human growth hormone - controls human growth.
● Stimulates the thyroid gland.
● Stimulates ovulation and the production of oestrogen in the ovaries.
● Stimulates the production of sperm and testosterone in the testes.

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50
Q

What is the role of the thyroid gland in the endocrine system?

A

Secretes the hormone thyroxine - controls metabolism, heart rate and body temperature.

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51
Q

What is the role of the pancreas in the endocrine system?

A

Secretes the hormone insulin - controls blood glucose levels.

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52
Q

What is the role of the adrenal gland in endocrine system?

A

Secretes adrenaline - controls the body’s ‘fight or flight’ response.

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53
Q

What is the role of the ovaries in the endocrine system?

A

Secrete oestrogen, which coordinates the menstrual cycle and the development of female secondary sexual characteristics.

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54
Q

What is the role of the testes in the endocrine system?

A

Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics.

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55
Q

Which organ monitors and controls blood glucose concentration?

A

pancreas

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56
Q

How does the pancreas respond when blood glucose levels are too high?

A

The pancreas secretes the hormone insulin. Insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored.

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57
Q

How does the pancreas respond when blood glucose levels are too low?

A

The pancreas secretes the hormone glucagon. Glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood.

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58
Q

How is blood glucose concentration controlled using a negative feedback loop?

A

● When the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas.
● The action of either hormone (insulin or glucagon) helps bring back the concentration to the correct level.

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59
Q

What is type 1 diabetes?

A

Type 1 diabetes is an autoimmune disorder in which the pancreas does not produce sufficient insulin to control the blood glucose concentration. As a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss.

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60
Q

How can type 1 diabetes be treated?

A

● Insulin injections before meals - allows glucose to be converted into glycogen.
● Limiting carbohydrate intake.
● Attempts using pancreas and pancreatic cell
transplants; investigations into genetic engineering of pancreatic cells.

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61
Q

What is type 2 diabetes?

A

Type 2 diabetes is a disorder in which the body’s cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. Its onset is linked with increasing age and obesity.

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62
Q

How can type 2 diabetes be treated?

A

● Following a carefully-controlled diet
● Doing regular exercise
● Losing weight
● Use of drugs which increase insulin
production and effectiveness

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63
Q

What is osmosis?

A

Osmosis is the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane

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64
Q

In what ways is water lost from the body?

A

● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)

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65
Q

In what ways are ions lost from the body?

A

● Sweating
● Urine (some reabsorbed in the kidney)

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66
Q

How are excess amino acids excreted from the body?

A

● Excess amino acids are deaminated in the liver to form ammonia.
● Ammonia is toxic, therefore it is converted into urea
● Urea is excreted from the body via sweat and urine.

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67
Q

How do the kidneys maintain the balance of water and other substances in the body?

A

● Filter blood in order to remove waste products eg. urea.
● Selectively reabsorb useful molecules eg. glucose, water, ions.

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68
Q

What is the full name of the hormone ADH?

A

anti-diuretic hormone

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69
Q

Where is ADH secreted in the body?

A

Pituitary gland of the brain

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70
Q

How does ADH affect the re absorption of water in kidneys?

A

● When the blood is too concentrated, the pituitary gland secretes more ADH.
● ADH travels in the bloodstream to the kidney and increases the permeability of kidney tubules to water.
● More water is reabsorbed in the kidneys, resulting in a smaller volume of more concentrated urine.

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71
Q

Why is kidney failure dangerous?

A

When the kidneys are damaged, they may be unable to filter the blood properly. This may lead to:
● A build-up of toxic molecules (eg. urea) in the body.
● An uncontrolled ion and water balance and cells being damaged as a result of osmosis.

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72
Q

What are the two main ways of treating kidney failure?

A

dialysis and transplant

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73
Q

What is kidney dialysis?

A

Kidney dialysis is the use of a specialist machine to carry out the function of kidneys. Dialysis fluid contains the same concentration of glucose and ions as healthy blood. As a result, only excess and waste molecules are lost from the blood, and glucose and ions remain.

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74
Q

What is the function of reproductive hormones during puberty?

A

● Males: cause the development of secondary sexual characteristics.
● Females: cause the development of secondary sexual characteristics and the maturation of eggs.

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75
Q

What is the main male reproductive hormone?

A

The main male reproductive hormone is testosterone, which is produced by the testes and controls sperm production.

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76
Q

What is the main female reproductive hormone?

A

The main female reproductive hormone is oestrogen, which is produced by the ovaries and is involved in the menstrual cycle.

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77
Q

What is the menstrual cycle?

A

The menstrual cycle is the monthly cycle of physical changes that occur in females, involving the shedding of the uterus lining (menstruation) and ovulation

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78
Q

Describe the events of the menstrual cycle

A

● Uterus lining thickens and eggs begin to mature in the ovaries.
● An egg is released from one of the ovaries (ovulation) - uterus lining remains thick.
● If the egg is fertilised, pregnancy may occur. If not, both the egg and the uterus lining are shed during menstruation.

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79
Q

What is ovulation?

A

Ovulation is the release of a mature egg from the ovaries, which occurs approximately every 28 days.

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80
Q

What are the four main hormones involved in the menstrual cycle?

A

● Oestrogen
● Progesterone
● Follicle stimulating hormone (FSH)
● Luteinising hormone (LH)

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81
Q

What is the role of FSH in the menstrual cycle?

A

FSH is secreted by the pituitary gland. It controls the maturation of eggs within the ovaries (inside a follicle) and triggers the production of oestrogen by the ovaries.

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82
Q

What is the role of oestrogen in the menstrual cycle?

A

Oestrogen is produced by the ovaries and released due to the action of FSH - it causes the regrowth of the uterus lining. It triggers the production of LH and restricts the release of more FSH.

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83
Q

What is the role of LH in the menstrual cycle?

A

LH is produced in the pituitary gland as a result of oestrogen. Its release triggers ovulation.

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84
Q

What is the role of progesterone in the menstrual cycle?

A

Progesterone is secreted from the follicle of the ovary. It sustains the uterus lining and inhibits FSH and LH.

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85
Q

What is contraception?

A

Contraception refers to any method of preventing pregnancy.

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86
Q

What are the two types of oral contraceptives?

A

● Combined contraceptive pill (contains oestrogen and progesterone).
● Mini pill (contains only progesterone).

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87
Q

How does the contraceptive pill prevent pregnancy?

A

● Inhibits FSH - eggs do not mature.
● Prevents the development of the uterus lining - eggs cannot implant.
● Increases the thickness of cervical mucus - immobilises sperm cells.

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88
Q

What is the contraceptive patch?

A

● Contains both oestrogen and progesterone.
● It is a patch that is placed onto the skin for 7 days at a time.

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89
Q

What is the contraceptive implant?

A

A small rod inserted under the skin which continuously releases the hormone progesterone - lasts for 3 years.

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90
Q

What is the contraceptive injection?

A

An injection containing the hormone progesterone - lasts for approximately 3 months.

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91
Q

What is the IUS?

A

The IUS (intrauterine system) is a small plastic device that is inserted into the uterus. It releases progesterone which thickens cervical mucus and prevents the build-up of the uterine lining.

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92
Q

What is the IUD?

A

The IUD (intrauterine device) is a small copper-containing device inserted into the uterus, which prevents the implantation of embryos.

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93
Q

What is a spermicide?

A

A spermicide is a chemical that kills or immobilises sperm cells - however, they are not very effective, and work better when combined with barrier methods.

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94
Q

What is a barrier method of contraception?

A

A barrier method of contraception involves a physical separation between the sperm and the egg. They include:
● Condoms - thin sheath worn on the penis or inside the vagina - protects against STIs but may tear/break.
● Diaphragms - a thin cap placed over the cervix - prevent entry of sperm.

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95
Q

What surgical methods of contraception are available?

A

Sterilisation - in males, the sperm ducts are tied (vasectomy) and in females, the oviducts are tied.

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96
Q

What is abstinence?

A

Abstinence is the practice of not having sex, which also avoids pregnancy. Some people abstain from sex around the time of ovulation - this is known as the rhythm method, but it is quite unreliable.

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97
Q

How do fertility drugs increase the chance of pregnancy?

A

Many fertility drugs contain FSH - which stimulates oestrogen production and the maturation of eggs in the ovary. They also contain LH which triggers ovulation.

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98
Q

What is IVF?

A

IVF (in vitro fertilisation) is type of fertility treatment:
● Mother is given FSH and LH - stimulates maturation of eggs and ovulation.
● Eggs are fertilised using sperm in a laboratory - develop into embryos.
● 1 or 2 embryos are inserted into the mother’s womb.

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99
Q

What are the advantages of fertility treatment?

A

● Allows infertile couples to have children
● Can store a woman’s eggs for later

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100
Q

What are the disadvantages of fertility treatment?

A

● It can be a very expensive process.
● It has a low success rate - especially for older couples.
● Increases chance of multiple pregnancies - dangerous for mother and babies.
● Side effects of fertility drugs.

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101
Q

What is negative feedback?

A

Negative feedback is a type of control where the body responds to an increase or decrease in a factor by returning it to the optimum level.

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102
Q

What is thyroxine?

A

Thyroxine is a hormone released by the thyroid gland. Its release is triggered by the thyroid stimulating hormone (TSH). Thyroxine controls the body’s metabolic rate, growth and development.

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103
Q

How is the release of thyroxine controlled by negative feedback?

A

● Levels of blood thyroxine falls - detected by receptors in the brain.
● Pituitary gland releases more TSH.
● More thyroxine produced and released by the thyroid gland.
● Blood thyroxine level returns to normal.

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104
Q

What is adrenaline?

A

Adrenaline is a hormone secreted by the adrenal gland in times of stress. It is responsible for the ‘fight or flight response’.

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105
Q

What are the effects of adrenaline?

A

● Increase in heart and breathing rate - delivers oxygen and glucose to the body.
● Stored glycogen converted to glucose.
● Dilation of pupils.
● Increased mental awareness.
● Blood diverted away from digestive system tomuscles.

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106
Q

What is a tropism?

A

A tropism is the response of a plant to a specific stimulus.

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107
Q

What is phototropism?

A

Phototropism is the response of a plant’s shoot or root to light.

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108
Q

What is gravitropism?

A

Gravitropism is the response of a plant’s shoot or root to gravity.

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109
Q

What is auxin?

A

Auxin is a hormone which controls the growth of a plant’s shoots and roots. When auxin is unevenly distributed in a growing plant, the rate of growth will also be unequal.

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110
Q

How do plants shoots show positive phototropism?

A

One side of the shoot is in the light, causing auxin to move to the shaded side
At the shaded side, the cells are stimulated to grow - the shoot bends towards the light
As a result, photosynthesis can occur at the shaded side

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111
Q

How do plants shoots show negative gravitropism?

A

in a horizontal shoot, auxin accumulates in the lower side due to gravity
cells on the lower side of shoot grow more, causing the shoot to bend away from the direction of gravity

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112
Q

How do plant roots show positive gravitropism?

A

● In a horizontal root, auxin accumulates in the lower side, causing cells to grow less.
● The root bends in the direction of gravity
● As a result, more water and nutrients are available to the plant roots.

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113
Q

What are gibberellins?

A

Gibberellins are a type of plant hormone involved in seed germination.

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114
Q

What is ethene?

A

Ethene is a type of plant hormone involved in cell division and ripening.

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115
Q

What are the uses of auxins?

A

● Weedkillers - auxin causes cells to grow at a rapid rate, causing plant death.
● Rooting powder - auxin causes new plant to grow very quickly.
● Tissue culture - auxin promotes growth of roots and shoots.

116
Q

What are the uses of ethene?

A

● Control of food ripening in the food industry - allows fruit to be ripened just before they are sold.

117
Q

What are the uses of gibberellins?

A

● Termination of seed dormancy
● Promotion of flowering
● Increase of fruit size

118
Q

What is internal change?

A

A change in conditions that occurs within a cell or organism

119
Q

What is external change?

A

A change in conditions that occurs outside of a cell or organism

120
Q

What is regulation?

A

To control or maintain conditions so that they work at their optimum rate

121
Q

What is optimal conditions?

A

The specific conditions that enables enzymes and cells to function at their best

122
Q

What is nervous response?

A

An electrochemical response brought about by nerve cells

123
Q

What is chemical response?

A

A chemical response brought about by hormones

124
Q

What is the blood glucose level?

A

The blood sugar level in the body which is controlled by homeostasis to regulate respiration and metabolism

125
Q

What is body temperature?

A

The amount of heat in the body which is controlled by homeostasis to ensure enzymes function properly

126
Q

What is water level?

A

The amount of water in the body which is controlled by homeostasis to regulate conditions for osmosis

127
Q

What is automatic control system?

A

A control system that operates without human intervention

128
Q

What is receptor?

A

Cells that detect stimuli

129
Q

What is stimuli?

A

Changes in the environment

130
Q

What is coordination centre?

A

Brain, spinal cord and pancreas that receive and process information from receptors

131
Q

What is effectors?

A

Muscles or glands which bring about responses to restore optimum levels

132
Q

What is a hormone?

A

A chemical produced by the endocrine system which carries messages

133
Q

What is thermoregulatory centre?

A

The area of the brain that is sensitive to the temperature of the blood

134
Q

What is temperature receptors?

A

Cells which respond to temperature changes in the skin and body

135
Q

What are nervous impulses?

A

Electrical signals that are sent from temperature receptors to the thermoregulatory centre during a response to temperature change

136
Q

What is vasodilation?

A

The widening of blood vessels which increases the amount of blood near the skin’s surface, allowing more heat to be transferred to the surroundings

137
Q

What is sweat?

A

The liquid produced by the sweat glands which reduces heat energy from the skin as it evaporates

138
Q

What are sweat glands?

A

Glands located in the skin that are responsible for the production of sweat

139
Q

What is vasoconstriction?

A

The narrowing of blood vessels that reduces the amount of blood near the skin’s surface, allowing less heat to be transferred to the surroundings

140
Q

What is shivering?

A

The rapid involuntary contraction of skeletal muscle which leads to increased respiration rates and energy released as heat

141
Q

What happens if the body temperature gets to high?

A

Blood vessels vasodilate and skin releases sweat

142
Q

What happens if the body temperature gets to low?

A

Blood vessels vasoconstrict and shivering starts

143
Q

What is the brain?

A

A mass of nerve tissue consisting of billions of interconnected neurones that acts as the main control centre of the nervous system

144
Q

What is brain mapping?

A

A set of neuroscience techniques used to create a map of the various brain areas and their functions

145
Q

What is a neuroscientist?

A

A scientist who studies the brain and nervous system

146
Q

What is magnetic resonance imaging (MRI)?

A

Can be used to look at which parts of the brain are most active during certain activities

147
Q

What is MRI scanner?

A

A type of scanner that uses strong magnetic fields and radio waves to produce images of inside of the body

148
Q

What is an electrical stimulation?

A

Can be used to look at behaviour in response to stimulation and narrow down specific brain regions to their functions

149
Q

What is electroencephalogram (EEG)?

A

A test that detects and records electrical activity in the brain

150
Q

What do you do to examine brain damage?

A

To look at areas of damage and link these areas to their function by seeing what effects the damage causes

151
Q

What is brain damage?

A

Injury to a particular part or parts of the brain

152
Q

What is brain surgery?

A

Needed to remove tumours or excess fluid such as blood

153
Q

What does complex structures mean?

A

It can be difficult to work out which parts carry out what function

154
Q

Why is difficult to access the brain?

A

A complication of brain investigation that can be overcome using techniques such as EEG or MRI scanners

155
Q

What are the consequences of brain surgery?

A

There is a possibility of damaging the brain further or side effects can be created which can affect quality of life

156
Q

What is brain disease?

A

Damage to the brain caused by illness or trauma

157
Q

What is the pupil?

A

Centre of the iris, it varies in size to regulate the amount of light that reaches the retina

158
Q

What are ciliary muscles?

A

Works with the suspensory ligaments and can contract or relax to adjust the shape of the lens

159
Q

What is suspensory ligaments?

A

Works with the ciliary muscles and can loosen or be pulled tight to adjust the shape of the lens

160
Q

What are the causes of hyperopia?

A

When the lens is too weak or the eyeball is too short

161
Q

What are the causes of myopia?

A

When the lens is too strong or eyeball is too long

162
Q

What are convex lenses used for?

A

Used for correcting hyperopia by moving an image forward and focusing it on the retina

163
Q

What are concave lenses used for?

A

Used for correcting myopia by moving an image further back and focusing it on the retina

164
Q

What are modern sight treatments?

A

Hard and soft contact lenses, laser surgery and lens replacement

165
Q

What is the hindbrain?

A

The lower part of the brainstem that include the cerebellum

166
Q

What is the eye?

A

A sense organ that detects light and is responsible for vision

167
Q

What is sclera?

A

The white outer part of the eye that provides protection

168
Q

What is optic nerve?

A

The nerve that carries neural impulses from the receptor cells of the eye to the brain

169
Q

What is light receptor cells?

A

Also called rod cells, these are highly light sensitive and are responsible for vision in dimly-lit conditions

170
Q

What is colour receptor cells?

A

Also called cone cells, these can detect a wide spectrum of light and are responsible for the perception of colour

171
Q

What is the reaction time?

A

The amount of time taken to respond to a specific stimulus

172
Q

How do you measure reaction time?

A

Catch a dropped ruler from a specific height, record the length caught in metres and then convert this into reaction time in seconds

173
Q

What is a conversion table?

A

A table that uses a formula to convert the distance of a caught ruler into reaction time in seconds

174
Q

What is the nervous system?

A

The network of nerve cells and fibres that transmits nerve impulses between parts of the body

175
Q

What are neurones?

A

Basic cells of the nervous system that carry electrical impulses around the body

176
Q

What is the central nervous system (CNS)?

A

The brain and the spinal cord

177
Q

What is the peripheral nervous system?

A

The parts of the nervous system outside of the brain and spinal cord such as the sensory and motor neurones

178
Q

What is a sensory neurone?

A

A neurone that carries impulses from the sensory organs to the central nervous system

179
Q

What is a coordinator?

A

The central nervous system which formulates a response to a stimulus before sending impulses to an effector

180
Q

What is a motor neurone?

A

A neurone that sends impulses from the CNS to an effector

181
Q

What is response?

A

A reaction to a stimulus

182
Q

What is the reflex arc?

A

A shorter nerve pathway involved in a reflex action made up of a sensory neurone, relay neurone and a motor neurone

183
Q

What is relay neurone?

A

A short type of neurone that is involved in reflex actions and is found in the spinal cord

184
Q

What is a reflex response?

A

A quick and involuntary reaction to a stimulus such as moving a hand away from a hot object

185
Q

What is synapse?

A

A junction or gap between neurones where information in chemical form is transmitted from one neurone to the next

186
Q

What is neurotransmitter?

A

A chemical that is released from the ends of an active neurone and diffuses across the synapse to other neurones

187
Q

What is negative feedback loop?

A

Where a change in something brings about a process that causes the opposite effect, keeping levels constant

188
Q

What is positive feedback loop?

A

A process in which the end products of an action cause more of that action to occur in a feedback loop, for example adrenaline promotion

189
Q

What is thyroxine or thyroid hormone?

A

A hormone which stimulates the basal metabolic rate and plays an important role in growth and development

190
Q

What is thyroid gland?

A

Releases thyroxine in response to stimulation by TSH

191
Q

What is thyroid-stimulating hormone (TSH)?

A

A hormone released by the pituitary gland which stimulates the thyroid gland to release thyroxine

192
Q

What is thyroxine negative feedback?

A

When thyroxine levels are high, thyroxine inhibits itself by signalling the pituitary gland to stop releasing TSH

193
Q

What is basal metabolic rate?

A

The rate of activity from basic life-sustaining metabolic processes that occur in the body, even when at rest

194
Q

What is the fight or flight response?

A

A physiological reaction that occurs in response to a stimulus that is perceived as being stressful

195
Q

What is stress?

A

Exposure to a negatively perceived stimulus that can be physical or emotional

196
Q

What is increased heart rate?

A

Blood is pumped quicker during fight or flight and can reach key structures quickly to provide them with glucose and oxygen

197
Q

What is increased ventilation rate?

A

Gas exchange can occur quicker during fight or flight so that more oxygen is available for aerobic respiration

198
Q

What does reduced blood supply to the gut do?

A

Reduces the supply of glucose and oxygen to digestive organs, which are not a priority during fight or flight

199
Q

What does increased blood supply to the brain and muscles do?

A

Provides the brain and muscles with more glucose and oxygen during fight or flight, allowing quicker responses to stressful stimuli

200
Q

What does the pancreas during fight or flight do?

A

Inhibits insulin and promotes glucagon so that increased levels of glucose are available for respiration

201
Q

What does negative feedback of reproductive hormones do?

A

If the levels of one reproductive hormone are too high, another reproductive hormone such as progesterone will inhibit it

202
Q

What does negative feedback of insulin and glucagon do?

A

High levels of blood glucose leads to insulin production and low levels of blood glucose leads to glucagon production

203
Q

What are hormonal methods?

A

Contraceptive methods that involve the use of hormones to inhibit other reproductive hormones and prevent egg implantation

204
Q

What are non-hormonal methods?

A

Contraceptive methods such as barrier methods that do not involve the use of hormones

205
Q

What are barrier methods?

A

Contraceptive methods that prevent the sperm from reaching the egg

206
Q

What is oral contraceptive?

A

A contraceptive such as the combined pill which must be swallowed to work

207
Q

What is the combined pill?

A

An oral contraceptive containing oestrogen and progesterone that inhibits other hormones and prevents egg formation and implantation

208
Q

What is progesterone-only pill (POP)?

A

An oral contraceptive containing just progesterone to reduce the chances of side effects associated with oestrogen

209
Q

What is a condom?

A

An effective barrier method that is also the only contraceptive capable of preventing sexually-transmitted infections

210
Q

What is femidom?

A

A female condom that is worn inside of the vagina during sexual intercourse

211
Q

What is a diaphragm or cap?

A

A long-lasting barrier method that is inserted into the vagina and covers the cervix to prevent sperm from reaching the uterus

212
Q

What is intrauterine device (IUD)?

A

A T-shaped copper-coated device that is professionally inserted into the uterus and can kill sperm or prevent the implantation of an embryo

213
Q

What is intrauterine system (IUS)?

A

A T-shaped plastic device that is professionally inserted into the uterus and releases progesterone to inhibit egg development

214
Q

What are injection, implant or skin patch?

A

Sources of slow release progesterone which inhibits the maturation of eggs for a number of months or years

215
Q

What are spermicidal agents?

A

Kills or disable sperm to reduce the chances of pregnancy, often used in combination with other contraceptive methods

216
Q

What is family planning?

A

Careful planning by individuals regarding pregnancy and contraception that may involve research and education, can be mediated by professionals

217
Q

What reasons are there for specific contraceptive choices?

A

Lifestyle, effectiveness, risk of side effects, permanence of method, infection prevention, ease of application, frequency of use

218
Q

What are FSH interaction with other hormones?

A

Causes follicle growth which promotes the release of oestrogen from the ovaries

219
Q

What is follicle-stimulating hormone (FSH)?

A

Stimulates the growth of a follicle and promotes the maturation of an egg in the ovary

220
Q

What is oestrogen interaction with other hormones?

A

Promotes the release of LH from the pituitary gland and inhibits the release of additional FSH

221
Q

What is luteinising hormone (LH)?

A

Responsible for ovulation by stimulating the release of the egg from a follicle in the ovary

222
Q

What are LH interaction with other hormones?

A

Causes the corpus luteum to form which promotes the release of progesterone from the ovaries

223
Q

What is progesterone?

A

Maintains the lining of the uterus during the latter part of the menstrual cycle and during pregnancy

224
Q

What is progesterone interaction with other hormones?

A

Inhibits FSH and LH production as an example of negative feedback

225
Q

What happens if fertilisation does not occur?

A

The corpus luteum dies and levels of progesterone decreases, resulting in menstruation and the start of a new cycle

226
Q

What is corpus luteum?

A

A structure in the ovaries that forms from a follicle when an egg is released, releases progesterone

227
Q

What is the ovary?

A

An organ of the female reproductive system where egg development occurs and oestrogen and progesterone are released

228
Q

What is infertility?

A

Where a couple are not able to conceive which could be due to age, cancer, faulty sperm production or other reproductive system complications

229
Q

What is a fertility drug?

A

FSH and LH can be supplemented as a treatment for infertility

230
Q

What is in vitro fertilisation (IVF)?

A

A process where eggs are extracted from the ovary and are artificially fertilised outside of the body, before implanting back into the uterus

231
Q

What happens in the early stages of IVF?

A

FSH and LH are given to stimulate egg development, eggs are then collected from the mother’s ovaries

232
Q

What is incubation stage of IVF?

A

Eggs are kept in a laboratory and are fertilised with sperm from the father, eggs are left to develop into embryos

233
Q

What happens in later stages of IVF?

A

When embryos are tiny balls of cells, one or two embryos are inserted into the mother’s uterus where foetal development can occur

234
Q

What is a surrogate mother?

A

Someone who volunteers to carry a baby in their womb, usually when the biological mother is not able to do so

235
Q

What are the complications of fertility treatments?

A

Can be stressful, with low success rates and can also lead to multiple births which is a risk to the mother and babies

236
Q

What is secondary sexual characteristics?

A

Characteristics caused by reproductive hormones that develop during puberty such as body hair and pelvic build

237
Q

What is the menstrual cycle?

A

A hormone-controlled cycle that occurs in the female reproductive system to prepare for pregnancy

238
Q

What is menstruation?

A

The process of discharging blood and material from the lining of the uterus through the vagina, if pregnancy does not occur

239
Q

What is ovulation?

A

The release of an egg from a follicle in the ovary during the menstrual cycle

240
Q

What is an ovary?

A

An organ of the female reproductive system where egg development occurs and oestrogen and progesterone are released

241
Q

What is an uterus?

A

A muscular organ of the female reproductive system where a fertilised egg develops into an embryo and eventually a foetus

242
Q

What is the lining of the uterus?

A

The walls of the uterus that need to be maintained for an embryo to implant and develop

243
Q

What is a fallopian tube or oviduct?

A

The tube connecting the ovary and uterus, where the egg moves from the ovary and meets the sperm if intercourse has occurred

244
Q

What is a fertilised egg or zygote?

A

When a sperm cell and egg cell fuse and begin to develop into an embryo

245
Q

What does an egg cell contain?

A

Contains genetic information from the mother, needs to fuse with a sperm cell for fertilisation to occur

246
Q

What does a sperm cell contain?

A

Contain genetic information from the father, needs to fuse with an egg cell for fertilisation to occur

247
Q

What is a follicle?

A

A small sac that houses one developing egg cell and is found in the ovaries

248
Q

What is a pituitary gland?

A

The master gland that is responsible for releasing FSH and LH

249
Q

What are osmotic changes?

A

Changes in the levels of water and concentration of solutes in the body that can lead to adverse effects if not regulated

250
Q

What are effect of osmotic changes in cells?

A

Complications can occur regarding diffusion and osmosis or cells can burst or shrivel in extreme cases

251
Q

What is exhalation?

A

Water can leave the body via the lungs when exhaling air

252
Q

What are the difficulties regarding water balance?

A

There is no control over water, ion or urea loss by the lungs or skin

253
Q

What is urination?

A

The removal of excess water, ions and urea from the body via the kidneys

254
Q

What is urine?

A

Mixture of water, urea and excess minerals that is filtered from the blood by the kidneys and excreted

255
Q

What are kidneys?

A

A pair of organs in the urinary system that filter molecules in the blood and remove excess or waste products to form urine

256
Q

What is the bladder?

A

Where urine is stored after it is filtered by the kidneys, before it is removed from the body

257
Q

What is selective reabsorption?

A

The kidneys reabsorb key molecules such as glucose and some ions and water depending on how concentrated the blood is

258
Q

What is kidney failure?

A

When kidneys don’t work as well as they should due to disease or damage

259
Q

What is kidney transplant?

A

The transfer of a healthy kidney by a donor to a person with kidney failure

260
Q

What is dialysis?

A

A procedure to remove waste products and excess fluid from the blood in individuals with kidney failure

261
Q

What is hemodialysis?

A

Uses a machine and filter to remove waste products and excess water from the blood

262
Q

What is peritoneal dialysis?

A

Uses a catheter and a fluid that is placed in the abdominal cavity to remove waste products and excess water from the blood

263
Q

What are the issues of transplants and dialysis?

A

Transplants can be rejected by the body and dialysis affects lifestyle or can lead to diseases if complications occur

264
Q

What is glucagon?

A

Hormone released by the pancreas to increase blood glucose, converts glycogen in the liver back into glucose

265
Q

What is deamination?

A

Nitrogen is removed from excess amino acids in the liver so they can be excreted safely

266
Q

What is ammonia?

A

Toxic chemical that is converted to urea for safe excretion

267
Q

What is ADH?

A

Anti-diuretic hormone which causes more water to be reabsorbed back into the blood from the kidneys if blood water levels are low

268
Q

What are kidney tubules?

A

Where ADH acts to increase the permeability so that more water is reabsorbed back into the blood

269
Q

What is permeability?

A

The ability of particles to move through a membrane

270
Q

What is the endocrine system?

A

Consists of glands that control many of the body’s activities by producing hormones

271
Q

What is hormonal coordination?

A

Body functions which are controlled by hormones released by glands

272
Q

What is the target organ?

A

The organ toward which the effects of a hormone is directed

273
Q

What is the testis?

A

A gland of the endocrine system that produces testosterone to regulate male characteristics

274
Q

What is auxins?

A

Plant hormones that coordinate and control cell growth in response to light and gravity

275
Q

What are tropism?

A

When an organism such as a plant responds to a stimulus by turning or growing in a certain direction

276
Q

What is phototropism?

A

A change in the direction of a plant in response to light

277
Q

What is gravitropism or geotropism?

A

A change in the direction of a plant in response to gravity

278
Q

What is positive phototropism?

A

Most plant shoots grow towards a light source to increase the rate of photosynthesis

279
Q

What is negative phototropism?

A

Plant roots grow away from light sources as darker conditions such as the soil are more likely to provide moisture and minerals

280
Q

What is positive gravitropism?

A

Plant roots grow towards the centre of gravity to increase the chances of obtaining water and minerals from the soil

281
Q

What is negative gravitropism?

A

Plant shoots grow away from the centre of gravity to increase exposure to sunlight for photosynthesis

282
Q

What is the effect of auxins in shoots?

A

Auxins accumulate on the shaded side of plant shoots and promote cell elongation, causing the shoots to grow towards light

283
Q

What is the effect of auxins in roots?

A

Auxins accumulate on the lower side of plant roots and inhibit cell growth, causing the roots to grow towards gravity

284
Q

What is cell elongation in shoots?

A

Shaded cells stretch more in plant shoots so that the shaded side becomes longer than the light side, resulting in the shoots growing towards light

285
Q

What is the inhibition of cell growth in roots?

A

Cells on the lower side of plant roots stretch and grow less than cells on the upper side, causing the roots to grow down towards gravity

286
Q

What happens when foil covers the plant shoot tips?

A

Plant shoots grow upwards but do not grow towards light if foil covers plant tips, suggesting the tips of shoots are sensitive to light

287
Q

What happens when foil covers the plant shoot stems?

A

Plant shoots continue to grow towards light if foil covers stems, suggesting the stems and lower parts of shoots are not sensitive to light

GCSE Biology (7 decks)

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