Prediction questions (past exam questions) Flashcards
homeostasis is not included but most likely will be asked so key things to know about homeostasis:
definition
features of an automatic control system
homeostasis is the regulation of internal conditions of a cell or an organism to maintain optimum conditions for function in response to internal and external changes.
automatic control systems may involve nervous responses or chemical responses all control systems include
receptors- receptors detect a stimulus ( a change in the environment) environment could be internal conditions in the body such as blood glucose concentration or external conditions such as skin temperature. receptors pass information onto the co ordination centre
co ordination centre- brain, pancreas, or spinal cord recieves or processes information from receptors and sends this information to the effectors
effectors are muscles or glands which carry out a response to restore optimum levels.
the only thing being assessed in the Human nervous System is control of body temperature 4. 5.2.4 here is everything about this topic:
body temperature is monitored and controlled by the thermoregulatory centre in the brain. the thermoregulatory centre contains receptors that are sensitive to temperature of the blood. Skin also has temperature recpetors which send electrical impulses down the sensory neurone to the brain.
you need to know what happens when body gets too hot or too cold
underneath the surface of the skin is a network of capilliaries that bllod vessels supply blood to, when we get too hot the blood vessels that supply these capilliaries dilate ( vasodilation) they dilate so that more blood travels to the capilliaries so that more heat can be transferred out of the blood and radiated from the skin, transferring energy to the surroundings. this allows our temperature to return to normal. we also sweat and the evaporation of sweat has a cooling effect on the body. both sweating and vasodilation cause energy to be transferred away from the skin to the environment.
part 2 of control of body temperature 4.5.2.4
when body temperature is too low
( everything is in detail but you dont have to memorise it word for word as it just explains the response)
when the body temperature is too low, sweating stops. we begin shivering. our skeletal muscles also contract. to provide energy for this contraction, the muscles increase their rate of respiration, as respiration is an exothermic reaction, it causes heat to be released which warms the body. vasoconstriction also occurs: the blood vessels supplying the network of capilliaries underneath our skin constrict, so the less blood flows through to the skin, this is so that less heat is transferred out of the blood and less heat is radiated out of skin to the surroundings.
some hard questions on this topic: explain how body would detect and respond to a decrease in temperature: 6 marks
any 6 from:
- the temperature receptors detect the change in temperature
- in the skin
- or in the thermoregulatory centre
- impulses are sent to the skeletal muscles
- to contract ( shivering)
- this requires lots of energy from respiration
- heat is produced as a result of exothermic reaction
- vasconstriction of capilliaries
- reduces blood flow to surface of skin
- reduces heat loss by radiation
- sweating production stops
even harder question: an athlete runs for 2 hours in temperatures of 35 degrees is air is dry without overheating however in humid conditions if temperature rises over 35 their body will overheat. suggest why person overheats in humid conditions.
(hint is to link with evaporation of sweat)
-body produces sweat
-heat is lost when water in sweat evaporates
-as air is humid it has a high water content
so less water can evaporate from person’s body so they cannot cool down
hormonal co-ordination human endocrine system
must know definition of the endocrine system and the basic ideas
definition- endocrine system consists of galnds which secrete hormones directly into the bloodstream. the blood carries these hormones around the body and each hormone has a specific target organ where it produces an effect.
compare the endocrine repsonse with nervous system response
-nervous system signalling is much more faster however the effects are short lived
-endocrine system has slower response but effects are long lasting
-nervous system- nerve impulses (nervous response)
-endocrine system- secrets hormones ( chemical response)
PITUITARY GLAND- master gland secrets several hormones into the blood in repsonse to body conditions. pituitary hormones act on other glands to trigger the release of OTHER hormones to bring about effects. By acting on other glands pituitary hormones trigger a range of different effects in the body.
part 2 of endocrine system: glands in the body and their and effects
piuitary gland- master gland secrets several hormones in the blood in response to body conditions
thyroid gland- releases hormones ( thyroxine) which are involved in growth and development and in controlling the basal metabollic rate (how fast chemical reactions occur in the body)
adrenal glands- produce adrenaline which is produced in times of fear and stress and is involved in fight or flight response
pancreas- releases hormones that are involved in controlling blood glucose concentration
testes and ovaries release hormones which are involved in puberty and reproduction.
4.5.3.2 control of blood glucose concentration
must know use of insulin, glucagon where they are produced why they are produced and what they do in the body.
must know conditions of diabetes and their treatments( also how their treatments will help)
blood glucose concentration is monitored and controlled by the pancreas
If the blood glucose concentration is too high, the pancreas produces
the hormone insulin that causes glucose to move from the blood into the
cells. In liver and muscle cells excess glucose is converted to glycogen
for storage. As glucose is being taken up from the blood and stored, the blood glucose concentration returns to normal levels.
if blood glucose concentration drops too low pancreas releases glucagon which triggers liver and muscle cells to convert glycogen stores back into glucose. this glucose is released back into the body allowing levels to return to normal.
because insulin and glucagon have opposite effects on the blood glucose concentration, scientists say they form a negative feedback
blood glucose concentration part 2: diabetes
type 1 diabetes- when pancreas is not producing enough insulin, this leads to uncontrolled high blood glucose levels.
small question “ if emma went to the doctors and got diagnosed with type 1 diabetes what are the doctors most likely to prescribe her?”
answer= insulin injections. patients with type 1 must control and monitor their bood glucose levels and take insulin.
type 2- body cells stop responding to insulin.
treated with excersise ( because obesity is a major risk factor)
and with a carbohydrate controlled diet to prevent blood glucose levels from rising too high.
Homeostasis keeps conditions in the body relatively constant.
The amount of water in the body is controlled by homeostasis.
Kidney function is controlled by a gland in the brain.
Describe how the water content of the blood is controlled.
when water levels are too low, blood is too concentrated pituitary gland releases ADH which increases permeability of the kidney tubules so more water can pass into the kidney tubules. more water is reabsorbed due to increased permability of the tubules allowing water levels to return to normal, a lower volume of urine produced. more concentrated urine is produced.
when water levels too low pituitary gland inhibits the release of ADH so that less water passes into the kidney tubules, less water is reabsorbed greater volume of urine produced.
The concentration of glucose in the blood of the two vessels is different.
Explain why.
concentration of glucose in the hepatic vein is lower because blood has been carried from liver to heart means pancreas has released insulin which has caused the liver cells to store glucose as glycogen. so glucose has been taken up from the blood and stored which is why it has a lower concentration. the hepatic portal vein has a higher concentration because small intestine has absorbed ilots of glucose and glucose has not been converted yet by liver.
) The person does not eat any more food during the next 6 hours after the meal.
However, 6 hours after the meal, the concentration of glucose in the blood in
the hepatic vein is higher than the concentration of glucose in the blood in the
hepatic portal vein.
Explain why.
the blood glucose concentration has dropped too low after 6 hours because glucose has been converted and stored so as blood passes through hepatic vein in liver, glucagon released from the pancreas causes glycogen to be converted back into glucose. glucose is then released into the bloodstream.
how do decomposers break down dead plant and animal matter
decomposers such as bacteria and fungi break down dead plants and animal matter by secreting enzymes into the environment. the small soluble food molecules produced then diffuse into decomposer these materials are cycled through an ecosystem by decomposers returning carbon into the atmopsjere as carbon dipxide and mineral ions to the soil.
Describe how living things are involved in the constant cycling of carbon.
6 marks
Examples of Biology points made in the response:
• (green) plants photosynthesise
• photosynthesis takes in carbon dioxide
• (green) plants use carbon to make carbohydrate / protein / fat / organic compounds /
named (e.g. enzymes / cellulose)
• animals eat (green) plants (and other animals)
• (green) plants respire
• animals respire
• respiration releases carbon dioxide
• (green) plants and animals die
• microorganisms decay / decompose / rot / break down / feed on dead organisms
• microorganisms respire
Other than carbon dioxide name two carbon compounds found in plants
- carbohydrates
- proteins
- fats
