Energy requirements of plants and animals

1
Energy requirements of plants and animals

• Plants and animals require energy for
• Growth
• Activity
• Maintenance

2
Tolerance Range

• All organisms have tolerance ranges within which
  various internal conditions must be maintained.
• The maintenance of internal conditions is known
  as homeostasis.
• Organisms have an optimum level for internal
  conditions

3
Tolerance Range
Tolerance Range
4
Feedback systems

• In order for organisms to maintain stable
  internal conditions, they have a range of
  regulatory mechanisms known as homoeostatic
  responses.
• Homeostasis ensures that internal conditions
  remain within the normal tolerance range for
  individual organisms.

5
Negative Feedback Systems

• Negative feedback systems regulate internal
  conditions by constantly monitoring changes in
  the internal environment and then making
  adjustments based on these changes.
• Negative Feedback Systems use changes in internal
  conditions as a stimulus. The organs responsible
  for detecting changes in the environment are
  known as receptors.

6
Negative Feedback Systems

• Messages detected by the receptors, about changes
  in the internal conditions, are normally received
  by a coordinating centre known as a modulator.
  These modulators are often found in the central
  nervous systems of organisms.

7
Negative Feedback Systems

• Once the stimulus information is coordinated in
  the modulating centre, then an appropriate
  response from an effector is normally solicited.
  The effector initiates changes in the physiology
  of an organism which result in a change in
  internal conditions towards the optimum.

8
Negative Feedback Systems
9
Negative Feedback Systems
10
Negative Feedback Systems
Time
11
Question Set 1

• Explain the difference between an optimum level
  and tolerance range in living things.
• The optimum level for any internal factor is that
  level at which the performance of an organism is
  optimised.
• The tolerance range is the range for an internal
  factor in which an organism can function without
  adverse effects.

12
Question Set 1

• Draw a diagram to show the system by which an
  organism maintains its internal environment.

13
Question Set 1
14
Question Set 1

• What is the difference between homeostasis and a
  negative feedback system?
• Homeostasis is the maintenance of a constant
  internal environment, mediated by feedback
  systems.
• A system in which a change in the internal
  environment results in a homeostatic response
  which brings the internal factor back towards the
  optimum level.

15
Carbon Dioxide

• It is important to keep carbon dioxide levels
  within the tolerance range of animals because
• In large quantities carbon dioxide can change the
  pH of an organisms internal environment. This
  can have an adverse effect on the functioning of
  enzymes.
• Very low levels of carbon dioxide can also cause
  problems because the regulation of breathing
  rates in many organisms are often governed by
  levels of carbon dioxide.

16
Carbon Dioxide

• The relationship between controlling the levels
  of carbon dioxide and oxygen in the body is very
  close.
• If carbon dioxide levels increase, then generally
  speaking, the levels of oxygen in the body will
  be depleted.
• In order to decrease the levels of carbon
  dioxide, the body will increase ventilation rates
  (breathing).
• This will, in turn, increase the levels of oxygen
  in the body.

17
Glucose Control

• Glucose is a fundamental substance necessary for
  cellular respiration. It is used to provide the
  energy necessary for converting ADP and P into
  ATP, which is then used to drive other metabolic
  reactions.
• Levels of glucose in the body fluctuate based on
  food intake and activity levels. These
  fluctuations are monitored and adjusted by the
  pancreas.

18
Glucose Control
19
Glucose Control

• Glucose is the ready form of energy in the
  body, while glycogen is a complex carbohydrate
  which is used to store glucose energy in the
  body. Glycogen is predominantly stored in the
  liver and the skeletal muscles of the human body.

20
Glycogenesis

• This is the formation of glycogen from glucose.
  This glycogen would be stored in the liver and
  skeletal muscle.
• Glycogenesis would occur when there are excess
  amounts of glucose in the blood.
• Insulin, a hormone produced by the Beta cells in
  the pancreas, will cause the body to convert
  excess glucose into glycogen.

21
Glycogenolysis

• This is the process which converts glycogen into
  glucose for use in cellular respiration.
• Glycogenolysis occurs predominantly when there
  are low glucose levels in the blood.
• Glucagon, a hormone produced by Alpha cells in
  the pancreas, results in glycogen being converted
  into glucose.

22
Gluconeogenesis

• This process occurs predominantly when both the
  levels of glucose and glycogen are low in the
  blood system.
• In this process, substances other than glycogen
  are converted into glucose. The substances
  converted into glucose might include fats and
  proteins.

23
Water Balance

• The amount and concentration of water within an
  organism, and the relative concentration compared
  to the environment is extremely important.
• Water is required because all of the metabolic
  activities of living things take place within a
  water soluble environment.

24
Water Balance

• The concentration of dissolved substances is also
  very important since the concentration of various
  substance can affect the rate at which essential
  metabolic reactions take place.
• Finally, the relative concentration of an
  organism compared to an environment will affect
  the rates at which passive forms of transport
  take place.
• An organism can be adversely affected, via the
  osmotic loss or gain of water, if the
  concentration of its body does not suit its
  environment and its internal tolerance limits.

25
Water Balance
26
Temperature

• It is important for temperature to be maintained
  within the tolerance range of an organism.
• Ectothermic organisms are those for which body
  temperature is largely controlled by the ambient
  temperature.
• Endothermic organisms are those for which body
  temperature is internally regulated.

27
Temperature

• The advantage of ectothermy is that minimum
  energy is invested by the organism into
  regulating body temperature.
• The disadvantage of ectothermy is that these
  organisms rely on the ambient temperature to
  provide the energy required for activity.
  Therefore, activity levels often coincide with
  high levels of ambient temperature.

28
Temperature

• The advantage of endothermy is that the
  activities of the organism can be undertaken
  independently of ambient temperature.
• The disadvantage of endothermy is that
  considerable amounts of metabolic energy are
  often required to maintain body temperature
  within tolerance ranges.
• Those organisms which are small and endothermic
  need to generate more heat via metabolic activity
  because they lose more heat to the environment
  through their relatively larger surface in
  relation to volume.

29
Temperature

• It is important to note that the control of body
  temperature is largely a case of balancing heat
  loss to the environment and heat gained from the
  environment and other means.
• The nett gain or loss of heat energy will
  determine the body temperature of an organism.

30
Temperature
31
Temperature

• If the temperature of an organism falls below its
  tolerance range then the normal chemical
  reactions which occur within cells gradually slow
  and ultimately stop. This is because the rate of
  any chemical reaction is greatly affected by
  temperature. Generally, we call a fall in an
  organisms temperature to below its tolerance
  range, hypothermia.

32
Temperature

• If the temperature of an organism rises above its
  tolerance range then the organism runs the risk
  of doing permanent damage to essential proteins
  in the body, such as enzymes.
• All proteins are denatured (their shape is
  changed) by extremes of temperature.

33
Temperature

• The shape of enzymes is essential for their
  normal functioning. If an enzyme is denatured by
  temperature then it ceases to be able to
  undertake its role as a chemical catalyst for
  essential metabolic reactions.
• Generally, if the temperature of an organism
  rises above its tolerance range, we call it
  hyperthermia.

34
Temperature
35
Temperature

• It is important to note that there are physical,
  physiological and behavioural mechanisms for
  controlling temperature.
• Organisms use different combinations of these as
  a means of maintaining normal body temperature
  within their tolerance range.

36
Temperature

• Physical adaptations for regulating body
  temperature include
• Piloerection body hair stands on end to reduce
  heat loss by convection over the surface of the
  body. (mammals)
• Adaptive increases or decreases in surface area
  Organisms may have increased or decreased surface
  area which allows for more efficient control and
  transfer of heat energy, as required. The large
  ears of many Australian marsupials are an example
  of using large surface areas to conduct/convect
  excess heat to the environment.

37
Temperature

• Physiological adaptations for regulating body
  temperature include
• Vasoconstriction and Vasodilation the control
  of blood flow to the extremities by reducing or
  increasing the diameter of blood vessels near the
  surface. This increases or decreases the rate of
  heat loss via conduction and convection.

38
Temperature

• Physiological adaptations for regulating body
  temperature include
• Evaporative Cooling including panting and
  sweating. Both means of losing excess heat to
  the environment via the energy needed to cause
  water to evaporate. As the water evaporates it
  carries excess heat energy with it into the
  atmosphere.

39
Temperature

• Physiological adaptations for regulating body
  temperature include
• Shivering increased, and spasmodic muscle
  movement, requires increased metabolic energy.
  Along with the energy needed for muscle
  contraction, heat is produced which helps to
  increase the temperature of the body.
• Changes in metabolic rate similar to above.
  Changes in metabolic rate will produce more or
  less heat as required to maintain body
  temperature within normal tolerance range.

40
Temperature

• Behavioural adaptations for regulating body
  temperature include
• Exposure control All of those behaviours which
  aim to increase or decrease exposure to extremes
  in ambient temperature. These include
• Basking in sun to increase temperature
• Hibernating or torpor during extremes of
  temperature
• Nocturnal habit which reduces exposure to
  extremely high temperatures.
• Burrowing to reduce exposure to extremes of
  temperature.

41
Temperature

• Behavioural adaptations for regulating body
  temperature include
• Increasing or Decreasing surface area available
  for heat exchange. This includes such things as
  huddling in groups and rolling into a ball to
  reduce heat loss to the environment. Similarly,
  organisms attempting to increase heat loss to the
  environment will spread out parts of their body
  to increase surface area.

42
Question Set 2

• Give the word equation for cellular respiration.
• C6H12O6 O2 ADP P ? CO2 H2O ATP

43
Question Set 2

• Which part of the human body is the effector for
  glucose control and explain how this occurs?
• Pancreas

44
Question Set 2
45
Question Set 2

• Why is it important to keep the temperature of an
  organism within its tolerance limits?
• If temperature rise above tolerance limits then
  there is a risk of denaturing the proteins of the
  body. Specifically, enzymes can be damaged so
  that they do not function thus blocking essential
  chemical reactions.
• If temperatures drop below tolerance limits then
  there is a risk of essential chemical reactions
  slowing and possibly stopping.

46
Question Set 2

• Give four means by which organisms adapted to
  regulate temperature.
• Refer to slides 26 to 41 for answers.

47
Wastes

• As a result of normal activity, living organisms
  produce waste materials.
• These waste materials can become toxic to the
  organism if they rise above normal tolerance
  limits.
• Organisms will expend energy to actively
  eliminate wastes from their body.

48
Nitrogenous Waste

• One of the most toxic wastes are those which
  result from the breakdown of nitrogen based
  compounds, such as proteins.
• The nitrogen based wastes produced are known as
  nitrogenous wastes. The main form of nitrogenous
  waste is ammonia (NH3). This can then be
  converted into urea or uric acid.

49
Nitrogenous Waste

• Ammonia is the simplest form of nitrogenous
  waste. It is
• Water soluble and requires large amounts of water
  to be removed from the body.
• Highly toxic so it must be eliminated from the
  body as quickly as possible.
• Low in energy cost to produce.
• Produced by fish and juvenile amphibians.

50
Nitrogenous Waste

• Urea is a more complex form of nitrogenous waste.
  It is
• Water soluble but requires less water to be
  eliminated from the organism. Normally leaves
  organism in a solution known as urine. Organisms
  that produce urea can normally control the
  concentration of their urine, thus allowing for
  the control of water loss.
• Toxic but not as toxic as ammonia.
• Produced using some energy.
• Produced by mammals.

51
Nitrogenous Waste

• Uric acid is a very complex form of waste. It
  is
• Water Insoluble and can be stored as a paste for
  extended periods of time.
• Non-toxic which also allows it to be stored for
  extended periods of time.
• Extremely energy hungry so requires large
  amounts of energy to be produced from ammonia.
• Produced by birds and reptiles.

52
Nitrogenous Waste
53
Osmosis

• Osmosis is the passive (does not use energy)
  movement of water, through a semi-permeable
  membrane, from an area of relatively low
  concentration of solution to an area of
  relatively high concentration of solution.

54
Osmosis

• If the concentration inside an organism is lower
  than the surrounding environment, then the
  organism is said to be hypotonic in relation to
  its environment.
• If the concentration inside an organism is higher
  than the surrounding environment, then the
  organism is said to be hypertonic in relation to
  its environment.
• If the concentration inside an organism is the
  same as the surrounding environment, then the
  organism is said to be isotonic in relation to
  its environment.

55
Osmosis
56
Osmotic Pressure in Animals

• Organisms can deal with the movement of water
  into or out of their body in a couple of ways
• They can maintain their body concentration at the
  same as their environment (isotonic). These
  organisms are known as osmoconformers.
• They can maintain body concentration within their
  normal tolerance limits which is either above
  (hypertonic) or below (hypotonic) their
  environment. These organisms are known as
  osmoregulators.

57
Osmotic Pressure in Animals
58
Osmoconformers

• Osmoconformers do not need to deal with a nett
  gain or loss of water because there is no osmotic
  pressure for water to enter or leave their cells.
• This group of organisms includes the sea anenome
  and jellyfish.

59
Fish in Salt water

• Fish which live in a salt water environment
  generally have a body concentration which is
  lower than their environment. They are
  hypotonic.
• This means that there will be a nett movement of
  water out of their body via osmosis.
• This also means that there will be a nett
  movement of salts into the body via diffusion.

60
Fish in Salt Water
61
Fish in Fresh Water

• Fish which live in a fresh water environment
  generally have a body concentration which is high
  than their environment. They are hypertonic.
• This means that there will be a nett movement of
  water into their body via osmosis.
• This also means that there will be a nett
  movement of salts out of their body via diffusion.

62
Fish in Fresh Water
63
Question Set 3

• What are the three forms of nitrogenous waste?
• Ammonia, Urea, Uric Acid

64
Question Set 3

• Why is nitrogenous waste produced by organisms?
• Nitrogenous waste is produced as a result of the
  breakdown of nitrogen based compounds, such as
  proteins.

65
Question Set 3

• Give a definition of osmosis.
• Osmosis is the passive (does not use energy)
  movement of water, through a semi-permeable
  membrane, from an area of relatively low
  concentration of solution to an area of
  relatively high concentration of solution.

66
Question Set 3

• Describe the movement of solutes and solvents in
  a fish which is living in salt water.
• Fish which live in a salt water environment
  generally have a body concentration which is
  lower than their environment. They are
  hypotonic.
• This means that there will be a nett movement of
  water out of their body via osmosis.
• This also means that there will be a nett
  movement of salts into the body via diffusion.

67
Question Set 3

• Describe the movement of solutes and solvents in
  a fish which is living in fresh water.
• Fish which live in a fresh water environment
  generally have a body concentration which is high
  than their environment. They are hypertonic.
• This means that there will be a nett movement of
  water into their body via osmosis.
• This also means that there will be a nett
  movement of salts out of their body via diffusion.

68
Plants dealing with water

• Plants must also maintain water balance.
• More complex, terrestrial plants must have
  mechanisms for maintaining a level of water
  within their tolerance range.
• They must also be able to move water around their
  body to meet the requirements of the various
  parts of the plant.

69
Angiosperms A vascular plant

• The angiosperms (flowering plants) have adapted
  to become vascular plants. They have specialised
  tissue for conducting water and nutrients around
  the plant.
• Angiosperms are generally terrestrial plants with
  a wide range of sizes, shapes and niches.
• The angiosperms live in a wide range of
  environments with varied water supplies.

70
Vascular Tissue

• Vascular plants have two types of vascular
  tissue.
• Xylem is responsible for carrying water which
  flows from the roots, up through the stems and
  out into the atmosphere through the stomata on
  the leaves.
• This flow of water is known as transpiration.

71
Xylem Vessels

• Xylem forms a network of continuous tubes
  throughout the plant
• Water moves through xylem by a combination of
  processes including capillary action, adhesion
  and cohesion of water molecules and osmotic
  pressure

72
Vascular Tissue

• Phloem is responsible for transporting water and
  nutrients from one location to another in a
  plant.
• This relocation of water and nutrients in known
  as translocation.

73
Phloem Vessels

• Phloem is shown here in cross section (top
  bottom) and longitudinal section (middle)
• It differs from xylem in that it is living
  tissue. It has to be living because it relies on
  active transport to move sugars around the plant

74
Transpiration

• This is the movement of water from the ground
  through a plant and out into the atmosphere
• Water travels in the xylem of roots, stems and
  leaves and exits the plant via the stomata
• This process also provides soil minerals to the
  plant, because they are dissolved in the water
• Excess water loss leads to the collapse of the
  plant (wilting)

75
Transpiration continued
76
Plant Adaptation

• In order to be successful in the wide range of
  environments, plants adapt various features to
  better suit them to their environment. These
  include
• Leaf size and colour
• Stomatal Rhythm
• Stomatal structure and distribution
• Cuticle presence
• Growth habit
• Root shape and structure
• Reproductive strategy
• Photosynthetic rhythm
• Leaf hairs

77
Leaf Size and Colour

• In high light intensity environments, plants
  reduce both the amount of chlorophyll in leaves
  and the surface area of the leaves.
• In low light intensity environments, plants will
  have more chlorophyll in the leaves and the
  leaves will have a larger surface area.
• Plants may also take on a silver or grey colour
  to reflect more of the excess available light
• Plants may also vary the surface area of leaves
  exposed to intense light and heat by leaf rolling
  or hanging leaves vertically.

78
Stomatal Rhythm

• In order to reduce water loss through
  transpiration during the hottest parts of the
  day, plants will reduce the amount of time that
  stomata are open in daylight.
• Reversed or reduced stomatal rhythms mean that
  plants need to modify their photosynthetic
  processes.

79
Photosynthesis light dependent

• Plants with reversed stomatal rhythms will
  undertake light dependent phase photosynthesis
  during the day. This does not require the
  stomata to be open since light dependent phase
  photosynthesis only fixes light energy as
  chemical energy in the form of electron transfer
  molecules.
• This occurs in the stroma of choloplasts.

80
Photosynthesis light independent

• At night, when the loss of water through
  transpiration is less, plants with reverse
  stomatal rhythms will open their stomata. This
  allows essential gases to be exchanged with the
  environment. It is at this point that light
  independent phase photosynthesis can occur. This
  occurs in the stroma of choloplasts. Carbon
  dioxide enters the leaf through the stomata and
  oxygen exits.
• This gas exchange occurs in the spongy mesophyll
  of the leaf. This tissue has a large number of
  air spaces between the mesophyll cells to allow
  maximum gas exchange.

81
Stomatal Structure

• Another plant adaptation, used in arid
  environments, involves changes in the structure
  of stomata to reduce water loss gas exchange.
• The stomata may be sunken to provide a humid
  cavity above the opening and therefore reduce
  water loss.
• The stomata may be covered with flap-like cells
  which again promotes a humid environment above
  the stomatal opening.
• Stomata may also be found only on the underside
  of leaves which reduces their direct exposure to
  the direct heat of the sun.

82
Stomatal function

• Stomata open and close based on the turgidity of
  the guard cells. When they are turgid (ie full of
  fluid), the stomata are open. When they are
  flaccid, the stomata are closed.
• Guard cells contain more chloroplasts than the
  surrounding epidermal cells, so when they
  photosynthesise and accumulate sugars, they set
  up a concentration gradient so that water moves
  in by osmosis, and the stomata open
• This can create problems if water is scarce,
  because the plant may lose water faster than it
  can replace it from the soil. If this happens,
  the plant will wilt, and water will move out of
  the guard cells, closing the stomata.
• This solves the problem of water loss, but also
  prevents the uptake of CO2, and thus limits
  photosynthesis

83
Leaf adaptations
84
Leaf adaptations continued

• In the sections on the previous slide, can you
  see the structural adaptations of the leaves?
• Rank them in order of least adapted to a dry
  environment to most adapted.

85
Leaf Covering

• Some plants have developed a waxy cuticle which
  is impermeable to water. This reduces the loss
  of water through the surface of the leaf in arid
  environments.
• Leaves may also have leaf hairs which promote a
  humid region around the leaves. This in turn
  reduces water loss through transpiration.

86
Growth Habit

• Plants show varied growth habits in relation to
  their environment.
• Plants living in high rainfall areas tend to be
  larger with more branching and leaves. They tend
  towards tallness to allow them to compete with
  other plants for available light.
• Plants living in arid areas tend to be smaller
  and closer to ground with smaller leaves.
• Some plants, like Acacias, have reduced or absent
  leaves to reduce water loss. Instead they have
  modified stems known as phyllodes.

87
Root Structure

• Plants will also vary their root structure in
  different environmental conditions.
• They may grow long tap roots in extremely dry
  conditions. These plants are known as
  Phreatophytes.
• Other plants will use roots which range over a
  wide area, just below the ground, to increase the
  surface area over which water is collected.

88
Question Set 4

• Give four adaptations of plants for conserving
  water and explain how each of these works.
• Refer to slides 68-82 for answers.