Topic 2- Responses to a changing environment

Question 1

Homeostasis

Answer 1

The maintenance of a stable internal environment in an organism.

Question 2

Negative feedback system

Answer 2

If something in the body changes beyond a certain limit, then the change is detected and the body automatically responds to balance things up again.

Question 3

Thermoregulation

Answer 3

The maintaining of a steady body temperature (e.g. for us approx. 37.5 degrees C).

Question 4

Vasoconstriction (Higher)

Answer 4

Blood vessels at the surface of the skin become narrower to restrict blood flow and heat loss through radiation.

Question 5

Vasodilation (Higher)

Answer 5

Blood vessels at the surface of the skin become wider to increase blood flow and heat loss through radiation.

Question 6

Hypothalamus

Answer 6

Region of the brain that is responsible for controlling body temperature.

Question 7

Erector muscles

Answer 7

Control the hairs on the surface of the skin, these stand up when the erector muscles contract.

Question 8

Hypothermia

Answer 8

Very low temperatures resulting in great heat loss the body can lead to hypothermia and finally death. If body respiration can’t replace the heat loss, then your body gradually cools, it begins to malfunction and eventually ceases to function at all.

Question 9

Hyperthermia

Answer 9

Very high temperatures make you feel extremely uncomfortable as your body struggles to cope with the situation and you suffer from ‘heat exhaustion’ and then heatstroke - which can be fatal.

Question 10

Hormones

Answer 10

Chemical messengers in the blood that coordinate and control many body responses. Slower than nerves and act in a more general area.

Question 11

Gland

Answer 11

Hormones are secreted by glands e.g. the endocrine gland, and are usually transported to their target organs by the bloodstream which determines their speed of distribution.

Question 12

Target organ

Answer 12

The specific site at which a hormone acts.

Question 13

Nerve

Answer 13

Electrical messengers. Much faster than hormones and act on a very precise area.

Question 14

Shivering

Answer 14

Muscles contracting and relaxing very quickly to generate heat.

Question 15

Sweating

Answer 15

Sweat released from sweat glands evaporates off the surface of the skin to remove heat and cool the body down.

Question 16

Glucose

Answer 16

The simple type of sugar that travels in the blood stream.

Question 17

Glycogen

Answer 17

When excess glucose is removed from the blood it is stored as glycogen in the liver.

Question 18

Insulin

Answer 18

The hormone that acts to reduce blood glucose levels by converting glucose into glycogen at the liver.

Question 19

Glucagon

Answer 19

The hormone that acts to increase blood glucose levels by converting glycogen at the liver into glucose.

Question 20

Pancreas

Answer 20

The organ that produces and releases insulin and glucagon.

Question 21

Type 1 diabetes

Answer 21

Type 1 diabetes occurs when the pancreas produces much too little of the hormone insulin and in some cases, no insulin at all. This causes the blood glucose level to rise to potentially lethal levels.

Question 22

Type 2 diabetes

Answer 22

The type 2 diabetes condition is when the pancreas doesn’t make enough insulin or the person has become resistant to insulin so the body doesn’t even respond appropriately to any insulin present, and both will cause the blood sugar level to rise. Linked to obesity.

Question 23

BMI

Answer 23

Body Mass Index (BMI) = (body mass in kg) / (height in m)2

Question 24

Phototropism

Answer 24

A plants response to light.

Question 25

Geotropism (or gravitropism)

Answer 25

A plants response to gravity.

Question 26

Hydrotropism

Answer 26

A plants response to water.

Question 27

Positive tropism

Answer 27

The plant grows towards the stimulus.

Question 28

Negative tropism

Answer 28

The plant grows away from the stimulus.

Question 29

Neurone

Answer 29

Elongated cells that carry electrical signals or impulses all around the body.

Question 30

Relay neurone

Answer 30

Connects a sensory neurone to a motor neurone.

Question 31

Sensory neurone

Answer 31

Receives the stimulus and sends it to the CNS.

Question 32

Motor neurone

Answer 32

Sends the message from the CNS to the effector to carry out a response.

Question 33

CNS

Answer 33

Central nervous system- the brain and spinal cord.

Question 34

PNS

Answer 34

Peripheral nervous system- the nerves that lead from the spinal cord to the rest of the body.

Question 35

Auxin

Answer 35

A plant hormone that controls the growth of the tips of shoots and roots.

Question 36

Selective weedkillers (Higher)

Answer 36

Selective plant growth hormone based weed-killers have been developed that affect the growth development of broad-leafed weeds and eventually kill them, BUT, do not affect the grasses and cereals with narrow leaves.

Question 37

Fruit ripening hormones (Higher)

Answer 37

The ripening can be controlled while the fruit are still on the tree/bush or during transport to the warehouses/shops. You can therefore pick fruit before it is ripe and still quite firm - which means its less easily damaged in transport. You can then choose the time when the ripening hormone is added so the fruit is as fresh as it can be for you the consumer via the wholesaler, market vendor, small shop or giant supermarket!

Question 38

Seedless fruit hormones (Higher)

Answer 38

By applying growth hormones to the unpollinated flowers of some fruit plants, the fruits grow BUT not the seeds! Sometimes the plant hormones are applied after pollination, but still prevent the seeds developing. A very handy way of producing common varieties of seedless fruits like watermelons, grapes, bananas and many seedless citrus fruits, such as oranges, lemons and limes.

Question 39

Rooting powder (Higher)

Answer 39

Some plant cuttings won't always readily grow in soil or compost, but by adding a rooting powder to the compost containing a plant hormone like auxin, the growth of roots and subsequent shoots are greatly encouraged. It then enables a flower grower or market gardener to rapidly produce lots of clones of a particular plant - ideally, of the best quality plants.

Question 40

Gibberellins (Higher)

Answer 40

Gibberellin is another plant growth hormone used to stimulate seed germination, stem growth (taller) and flowering.

Question 41

Stimulus

Answer 41

Any change in your surroundings e.g. temperature, visual, sound etc. is potentially a detectable stimulus to one of you sensory organs e.g. skin, eyes, ears etc. The stimulus might be chemical, light, pain, position, pressure, sound, temperature, touch etc.

Question 42

Reflex arc

Answer 42

The response by-passes the brain, goes through a relay neurone to directly connect the sensory and motor neurone through the following pathway: stimulus ==> receptor cell ==> sensory neurone ==synapse==> relay neurone in central nervous system =synapse==> motor neurone ==> effector ==> response.

Question 43

Receptor cells

Answer 43

Detect the stimulus. In the receptor cells the stimulus input is converted into an electrical signal - an electrical impulse which is sent to the brain.

Question 44

Synapse

Answer 44

A connection between two neurones eg the junction between a sensory neurone and a relay neurone, it enables the electrical impulse signal to reach the spinal cord and brain (ie the central nervous system). Between the end of one neurone, and the start of another, chemicals (neurotransmitters) are released in the gap that rapidly diffuse across the gap in the synapse, transferring the electrical signal from one neurone to another.

Question 45

Neurotransmitter

Answer 45

Chemicals produced that transmit the electrical signal across a synapse gap between one neurone cell and another.

Question 46

Myelin sheath

Answer 46

A fatty electrically insulating tissue layer around the axon connections between neurones - the axon in the neurone cells carries the electrical signal - if there was no myelin insulation, the signal will be lost.

Question 47

Effectors

Answer 47

The muscles or glands that respond in a variety of ways to the electrical signal from the brain.

Question 48

Dendrons

Answer 48

Neurone cells have lots of branched endings called dendrons which connect with lots of other neurones.

Question 49

Axons

Answer 49

The electrical impulses of the nervous system are carried by thin 'fibres' called axons which are surrounded by an insulating myelin sheath.

Question 50

Liver

Answer 50

The target organ for the hormones insulin and glucagon.