Hsc Biology All Topics

Front 1

what is homeostasis?

Back 1

homeostasis is the process by which organisms maintain a relatively stable internal environment.

Front 2

explain in general terms why homeostasis is important

Back 2

all organisms are faced with fluctuations in their external environments, maintenance of a constant internal environment by controlling inputs and outputs is important for optimal metabolic efficiency

Front 3

identify the stages involved in the maintenance of homeostasis

Back 3

homeostasis consists of 2 stages:
detecting changes and responding to changes from the stable state.

Front 4

for a named plant, identify one response is shows to temperature change

Back 4

in some Aust. plants such as the BANKSIA, seed dispersal is stimulated by the extreme heat of a fire. the heat stimulates the fruit to open, releasing the seeds.

Front 5

outline the specific role of aldosterone

Back 5

aldosterone increases the amount of salt absorbed from the kidney tubules.

Front 6

outline the specific role of ADH (vasopression)

Back 6

ADH increases water reabsorption from the kidney tubules

Front 7

state one of the reasons why some people can't secrete aldosterone

Back 7

the inability to secrete alsosterone may be teh result of damage to the adrenal glands that produce the hormone either from surgery, accidents, or disease, or of damage to the pituitary gland that controls the adrenal gland.

Front 8

outline the general use of hormone replacement therapy in people who can't secrete aldosterone

Back 8

lack of aldosterone results in low levels in the blood - potentially dangerous conditions./ replacement therapy restores the balance of these salts.

Front 9

describe a current theory used to describe the movment of materials through the phloem.

Back 9

the transport if materials through the phloem is called translocation. a high-pressure region exists at the source or site of production of the sugars (the leaves). a low-pressure region exists near the sugar sink (eg. the roots). the change in pressure forces the sugar rich sap through the sieve columns, moving from the source to the sink.

Front 10

one of the materials transported in teh bodies of mammals is CO2. you carried out a 1st hand investigation to demonstrate the effect of dissolved CO2 on teh pH of water.
a) describe how you carried out this experiment
b) what was the results of your experiment
c)in the light of your results, what hypothesis could you make about the effect of dissolved CO2 on the pH of human blood?
d) justify the appropriateness of you experimental design

Back 10

a) method: add hydolic acid to calcium carbonate in a tt to produce CO2. fit with a cork and delivery tube and run gas produced into a known quantity of water containg Universal Indicator. determine pH by comparing colour of results with chart. determine the pH pf the same quantity of water to which no gas has been added containg the same amount of UI. repeat experiment.
b) water containg CO2 had a lower pH than teh same amount of water only did.
c)CO2 would decrease the pH of Human blood, making it more acidic.
d) a reliable source of CO2 was used variable were controlled where possible. repetition was used to increase reliability. a reliable means of testing pH was used.

Front 11

outline the need for oxygen in living cells

Back 11

oxygen is required for respiration to produce energy

Front 12

explain why the removal of CO2 from animal calls is essential

Back 12

removal of CO2 is essential because it reacts with water to produce carbonic acids in animals, which affects the uptake of oxygen and pH.

Front 13

state the specific functions of xylem and phloem in plants

Back 13

function of xylem is to transport water from the roots to the leaves' the phloem transports the products of photosynthesis around the plant.

Front 14

list the equipment or resources you would need to perform an investigation of transverse section of xylem and phloem tissues and describe how you would carry out the investigation.

Back 14

resources: celery, beaker of red coloured water, scalpel, cutting board, microscope, slides, cover slip.

Front 15

draw a labeled sketch of a transverse section of either xylem or phloem tissue

Back 15

labels should include epidermis, xylem, phloem, fleshy tissue

Front 16

you have investigate current theories about the processes responsible for the moment of materials through plants in xylem or phloem tissues. describe one of these theories.

Back 16

capillarity is one way water is transported within xylem vessels in plants. it describes the action by which the surface of a liquid is elevated when in contact with a solid surface as a result of the attraction between molecules of liquid and solid surfaces. the water molecules at the top of the column help pull up those below them

Front 17

a) name one estuarine plant.
b) out line the process that it uses for salt regulation in the estuarine environment

Back 17

a)mangrove.
b) enantiostasisis the process that mangroves use to maintain their salt/water balance. this is achieved by excreting salt from special glands in their leaves. they can also accumulate salt in their leaves and then shed the leaves.

Front 18

compare the responses of a names Aust ectotherm to that of an Aust endotherm regarding changes in ambient temperatures

Back 18

gecko - ectotherm. if temps low it lies close to the ground in the sun. if temps high it can lift its body from the ground or go to shady areas, under rocks etc.
a kangaroo - endotherm. in heat they lick their forelimbs to promote cooling by evaporation or remain in shade. when cold, blood vessels near teh skin are able to constrict, so reducing radiant heat loss.

Front 19

homeostasis consists of 2 stages. identify these stages and explain how they're related back to the feedback mechanism

Back 19

2 stages: detecting changes from stable state, and counteracting changes from stable state. these stages are related to the feedback mechanism by way of a loop. first, a change is detected, and a message is sent to the brain, which in turn sends a message to an effector organ to produce a response to counteract the change. once a balance has been reached another message is sent to stop the compensatory action.

Front 20

name one Aust plant that is adapted to the arid climate name and 2 adaptations of Aust terrestrial plants and explain who they assist in the survival of the plants in arid climates.

Back 20

BANKSIA.
thick waxy cuticles prevent water loss; lighter colour on the underside of leaves reflects light and helps prevent moisture loss through stomates.

Front 21

What is a scientific control?

What is it used for?

Back 21

scientific control is an experiment or observation designed to minimisee the effects of variables other than the single independent variable e.g.

Front 22

What do we use a scientific control for

Back 22

This increases the reliability of the results, often through a comparison between control measurements and the other measurements.