communication, homeostasis and energy

Question 1

What are 4 conditions that must be maintained within cells to ensure the survival of that cell?

Answer 1

-pH
-water concentration
-temperature
-prevent toxins build-up (e.g. CO2)

Question 2

What is cell signalling

Answer 2

the communication process that governs the basic activities of cells and coordinates multiple cell actions within multicellular organism

Question 3

What are some things cells might need to communicate about?

Answer 3

-carbon dioxide
-water concentration levels
-threats in the environment
-presentation of antigens
-release of cytokines
-temperature

Question 4

nervous system (neuronal)

Answer 4

if the response needs to be rapid because the stimulus changes quickly or is an immediate threat- the nervous system is used as neurons are able to conduct electrical impulses much faster) hormones travel in the blood
-responses are faster but only short-term

Question 5

endocrine system (hormonal)

Answer 5

the hormonal (endocrine) system uses the blood to carry chemical messengers
-slower but longer-lasting effects

Question 6

Peptide hormones with examples

Answer 6

types of hormones that have to bind to receptors on the cell membrane of their target tissues- e.g. binding of adrenaline to the liver cells
-e.g. glucagon, adrenaline and ADH are peptide hormones

Question 7

Steroid hormones with examples

Answer 7

do not bind to the cell but instead pass directly through the bilayer of the plasma membrane and any other membranes inside the cell
-able to do this as they are small and non-polar
-e.g. oestrogen

Question 8

Blood glucose concentration range

Answer 8

4-7 mmoL/L

Question 9

Body temperature

Answer 9

36-37.5 degrees C

Question 10

pH of blood

Answer 10

7.35-7.45 pH

Question 11

What is homeostasis?

Answer 11

the maintenance of a state of dynamic equilibrium and homeostatic control systems using the principle of negative feedback to maintain systems within narrow limits

Question 12

What is negative feedback?

Answer 12

in a homeostatic control system, the combination of the physiological responses of the effectors brings the aspect back towards the optimum and therefore reverses the original change (the stimulus).

Question 13

What is positive feedback?

Answer 13

involves a response that increases the original change

Question 14

What are sensory receptors?

Answer 14

detect stimuli

Question 15

What is a coordination centre?

Answer 15

receives and processes sensory input to coordinate a response

Question 16

What are effectors?

Answer 16

brings about a response
-muscles or glands

Question 17

Why is having a high blood water concentration dangerous?

Answer 17

-water moves from the blood into the cells by osmosis
-Due to the steep water potential gradient, lots of water moves into the cells by osmosis, causing those cells to swell
-Cells do not consist of a cell wall and the support that that would provide and so bursts (cytolysed)

Question 18

Why is having a low blood water concentration dangerous?

Answer 18

-water moves from cell into the blood by osmosis
-Water potential gradient lots of water moves out of the cells, mouse mouses, causing the cell to shrivel and shrink
-No cell wall so cell becomes crenated
-this reduces the surface area and the cells ability to perform its specific function
-The decrease in the amount of cytoplasm also causes a decrease in chemical reactions

Question 19

What is an ectotherm?

Answer 19

organisms that rely on external sources of heat and their body temperature fluctuates with external temperature

Question 20

What is an endotherm?

Answer 20

organisms that use heat from metabolic reactions to maintain their body temperature and are largely independent of external temperatures

Question 21

Behavioural responses of an ectotherm when body temperature is lower than it should be

Answer 21

-move to a sunny area to bask
-expose as much of their surface area to the Sun as possible

ectotherms rely almost exclusively on a range of these behavioural responses about endotherm‘s use, behavioural and physiological responses such as increased sweating to try to restore optimum levels

Question 22

Why may some ectotherms stay in burrows?

Answer 22

borrows have more stable temperatures than the air, so it may be cooler in the burrow at the hottest part of the day, but it may be warmer than air at night

Question 23

Advantages of ectotherms

Answer 23

-can use a greater proportion of energy from food to grow as energy is not needed to maintain body temperature
-Can survive for longer periods without food, as have lower metabolic demands/ need to eat this food

Question 24

Why is it more beneficial to have ectotherms than endotherms in the food chain?

Answer 24

as ectotherms do not use energy from metabolic reactions to control their temperature, less energy is lost meaning more is available for growth (forming biomass) and this will be passed onto the consumer

Question 25

Advantages of endotherms

Answer 25

-overall effectiveness of body temperature control
-Population will be found, inhabiting the colder parts of the world
-Ability to remain active when external temperatures are low

Question 26

What are many of the chemical reactions in the body known as being?

Answer 26

exergonic- they release energy in the form of heat

Question 27

What is a key physiological mechanism utilised by endotherms when the body temperature decreases?

Answer 27

an increase in the rate of respiration in muscles and livers, so that heat is released, causing the body temperature to increase