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A Level Biology > Topic 5.1.1 Communication > Flashcards

Topic 5.1.1 Communication Flashcards

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1
Q

Why do all living things need to have a communication system?

A

To survive, an organism must coordinate the activities of all cells within it in order to respond to a change in its internal or external environment.

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2
Q

What are some internal changes that organisms must respond to?

A
  • blood salt concentration
  • blood glucose concentration
  • temperature
  • cell pH, blood pH
  • water potential
  • carbon dioxide concentration
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3
Q

Explain how the internal changes listed can effect an organism, and why they must be responded to?

A
  • blood salt concentration = too much salt lowers the water potential of the blood causing water to move out of the cells via osmosis, too little causes water to move into the cell via osmosis - osmotic damage
  • blood glucose concentration = too much glucose lowers the water potential of the blood causing water to move out of the cells via osmosis, too little causes water to move into the cell via osmosis - osmotic damage
  • temperature = optimum temperature for enzyme activity, too hot and the enzymes will denature, too cold and there will be too little kinetic energy meaning less successful collisions between enzymes and substrates
  • pH = optimum pH for enzyme activity, too acidic or alkaline and the rate of enzyme activity will lower greatly
  • carbon dioxide concentration = effects pH in the blood (makes it acidic) which impacts the ability for enzymes to function
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4
Q

What are some external changes that organisms must respond to?

A
  • temperature
  • humidity
  • light intensity
  • new or sudden sound (anything that triggers a physical response)
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5
Q

Give two examples to demonstrate the significance of coordination within organisms.

A
  1. muscles need oxygen to respire - must rely on the red blood cells to supply this oxygen.
  2. flowering plants release certain chemicals that are sensitive to day length in order to coordinate with the pollinators by allowing the buds to form.
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6
Q

Why is coordination important in plants?

A
  • they don’t have a nervous system like animals
  • to survive they must respond to internal and external changes to their environment
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7
Q

Give an example of how plants show coordination.

A
  • chemical communication
  • plant hormones
    e.g. plants / stems will move towards the sunlight - detect hormones
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8
Q

How do cells communicate with each other?

A

Cell signalling

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9
Q

What is cell signalling?

A

The communication and coordination of cells using signals. Many molecules and internal processes within the cell act as signals e.g. cytokines

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10
Q

What is the process of cell signalling?

A

One cell (secreting cell) releases a chemical and a second cell (target cell) detects the chemical and responds to it.

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11
Q

Give an example of cell signalling in the body.

A

Insulin (a hormone) travels in the blood to a receptor cell and causes a cascade of events. The vesicles carry more carrier proteins to fuse with the cell membrane allowing more glucose into the cell.

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12
Q

Describe some features of the neuronal system of cell signalling.

A
  • uses neurones to transport signals
  • electrical impulses via neurones
  • a faster response
  • short term
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13
Q

Describe some features of the hormonal system of cell signalling.

A
  • uses blood to transport signals
  • chemicals / hormones via the blood
  • slower response
  • long term
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14
Q

Give a definition of homeostasis.

A

The maintenance of a constant internal environment despite changes in the external environment through different metabolic processes.

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15
Q

What is the process of homeostasis?

A
  1. Stimulus
  2. Receptor
  3. Communication pathway (specialised structures)
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16
Q

Define the term receptor

A

Extrinsic glycoproteins (carbohydrates + protein) that bind chemical signals and trigger a response by the cell

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17
Q

Define the term effector

A

A muscle or gland that carries out the body’s response to a stimulus

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18
Q

What are some examples of sensory receptors?

A
  • skin cells
  • retinas in the eyes
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19
Q

Define the term Negative Feedback.

A

Any change away from the optimum conditions is reverted back to the optimum - in order to maintain a constant internal environment.

20
Q

Give an example of Negative Feedback.

A

Temperature change in the body
- the hypothalamus detects if the body is too hot or too cold and negative feedback occurs

21
Q

What are the steps of Negative Feedback?

A
  1. Receptors detect the stimulus
  2. Input is passed on to the coordination centre
  3. Sends output to the effectors
  4. Effectors reverse the initial change in the conditions
  5. The system moves closer to the optimum
  6. The stimulus is now reduced
  7. Receptors now detect the reduction in the stimulus
  8. Input to the coordination centre is reduced
  9. Now the output to the coordination centre to the effectors is also reduced, and effectors reduce their activity
  10. The response is eventually reduced
22
Q

What occurs when the body gets too hot and Negative Feedback takes place?

A
  • vasodilation
  • sweating (gland)
23
Q

What occurs when the body gets too cold and Negative Feedback takes place?

A
  • vasoconstriction
  • shivering
24
Q

Define the term Positive Feedback.

A

A process that increases any change detected by the receptors. It tends to be harmful and does not lead to homeostasis.

25
Q

What are the steps of positive feedback?

A
  1. Optimum condition
  2. Change away from optimum (this is a stimulus)
  3. Detect the change (done by a receptor)
  4. Communicate the change (cell signalling)
  5. Respond to the change (involves an effector)
  6. Increase the change
26
Q

Give and explain some examples of positive feedback.

A

Hypothermia -
- due to the cold, molecules have less kinetic energy and metabolic reactions slow down, therefore exergonic reactions that release heat also slow down
- respiration slows down - less heat generated
- less energy - slower enzyme activity and slower vital metabolic reactions

Labour -
- head of foetus pushes against cervix
- pressure receptors from the cervix sends nerve impulses to the brain
- brain stimulates pituitary gland to secrete oxytocin
- oxytocin carried in bloodstream to uterus
- oxytocin stimulates uterine contractions and pushes foetus towards the cervix

27
Q

Give a definition of an ectotherm.

A

Animals that use their surroundings to warm their body. Their core body temperature is heavily dependant on their environment - rely on external sources of heat to maintain their body temperature.

28
Q

Give a definition of an endotherm.

A

An animal that is able to maintain a constant internal temperature through homeostasis regulating heat loss and gain.

29
Q

Explain why ectotherms living in water do not need to thermoregulate.

A

Water has a high specific heat capacity meaning a lot of energy is required to change the thermal environment, which is normally quite stable.

30
Q

What are some behavioural adaptations for ectotherms to aid with thermoregulation?

A

Cold - move into a sunny area, lie on a warm surface, expose a large surface area of the body to the sun
Hot - move out of the sun, move underground, reduce body surface area exposed to the sun

31
Q

Advantages of being an ectotherm include…

A
  • don’t use energy to keep warm as they rely on external sources of heat
  • less of their food is used in respiration
  • survive a long time without food
  • more of the energy and nutrients gained from food can be converted to growth
  • need to find less food
32
Q

Disadvantages of being an ectotherm include…

A
  • less active in cooler temperatures
  • more at risk from predators as they can’t escape and take advantage of food that is available
33
Q

What sort of responses do ectotherms use to alter how much heat they exchange with their environment?

A
  • physiological
  • behavioural
  • anatomical adaptations
34
Q

Advantages of being an endotherm include…

A
  • maintain a constant body temperature despite the environment - remain active so can hunt for prey or escape from predators
  • can inhabit colder parts of the world
35
Q

Disadvantages of being an endotherm include…

A
  • have to consume more food as not all energy is used for movement and growth
  • can overheat in hot weather
36
Q

What is involved in the process of thermoregulation in endotherms?

A
  • core temperature is kept constant
  • the hypothalamus contains a thermoregulatory centre which monitors changes in temperature of the blood
  • thermoreceptors in this centre detect changes in core temperature - send signals to reverse temperature changes
  • reversal involves physiological and behavioural responses
  • peripheral thermoreceptors in the skin monitor temperature changes in the extremities
  • they inform the thermoregulatory centre in the hypothalamus and act as an early warning system
  • they initiate behavioural responses such as moving into shade
37
Q

What are the six main components of the body in which physiological responses are carried out by endotherms to maintain body temperature?

A
  • sweat glands and the skin
  • lungs, nose and mouth
  • erector pili muscles
  • arterioles leading to capillaries in skin
  • liver
  • skeletal muscles
38
Q

How do the sweat glands and skin thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - secrete more sweat onto skin, water in sweat evaporates, using heat from blood to supply heat of vaporisation
too low - less sweat evaporates, cooling effect reduced

39
Q

How do the lungs, mouth and nose thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - open mouth and pant - water vapour is lose - helps to cool the endotherm
too low - close mouth and pant less - loss of water vapour is reduced

40
Q

How do the erector pili muscles thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - relaxation of the erector pili muscles - hair lays flat
too low - contraction of erector pili muscles raises hairs to trap a layer of insulating air, reducing heat loss from skin

41
Q

How do the arterioles leading to capillaries in the skin thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - vasodilation of the arterioles leading to the capillaries allowing more blood to flow near the skin surface - more heat loss
too low - vasoconstriction of arterioles and precapillary sphincters meaning blood is diverted away from capillaries near surface of the skin - less heat loss

42
Q

How does the liver thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - rate of metabolism is reduced, less heat is generated from exergonic reactions such as respiration
too low - more respiration - more energy from food is converted into heat energy - rate of metabolism increases

43
Q

How do the skeletal muscles thermoregulate an endotherm when the core temperature is too high or too low?

A

too high - fewer muscles contractions means less heat energy released
too low - spontaneous contractions (shivering) generates metabolic heat from exothermic reactions (muscles cells respire more)

44
Q

How do endotherms use behavioural responses to maintain body temperature?

A

too hot - move into shade or hide in burrow, orientate body to decrease surface area exposed to sun, remain inactive and spread out the limbs to increase surface area, take off some clothes
too cold - move into the direct sun, orientate body to increase surface areas expose to sun, move around more to increase activity or press themselves onto a warm surface, put on more clothes

45
Q

How does SA:V influence an organisms body temperature?

A
  • sa:v decreases as an organism gets bigger meaning it becomes more difficult for it to lose heat - the higher the sa:v, the faster an organism will lose heat energy
46
Q

What is the advantage of having receptors in the thermoregulatory centre and peripheral receptors in the skin?

A
  • combination of the two gives the body increased sensitivity - you can respond to actual changes in the blood and pre-empt possible problems that can occur because of the changes detected by the skin

A Level Biology (11 decks)

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