Higher Biology Unit 2: Metabolism and Survival (2.3 ... · Higher Biology Unit 2 Pupil Course Notes...

Higher Biology

Unit 2: Metabolism and Survival

(2.3) Metabolic Rate (2.4) Metabolism in Conformers and Regulators

Higher Biology Unit 2 Pupil Course Notes

Duncanrig Secondary School LS 2015 page 1 of 22

Unit 2: Metabolism and Survival

Sub-Topic (2.3) Metabolic rate

(2.4) Metabolism in Conformers and Regulators

On completion of this subtopic I will be able to

State that metabolic rate is the quantity of energy consumed by an organism per unit of time.

Metabolic rate can be measured as oxygen consumption per of unit time,

carbon dioxide production per unit of time or energy production as heat per

unit of time.

State that different types of organisms have different metabolic rates.

Compare the metabolic rate of different organisms.

Animals have various physiological adaptations to deliver oxygen to cells.

High metabolic rates require efficient delivery of oxygen to cells.

Describe the structure and circulation of the fish heart and lung structure.

Describe the structure and circulation of the amphibian and reptile heart and

structure of lungs

Describe the structure and circulation in the mammalian and bird heart and

structure of the lungs

Describe physiological adaptations that animals have to survive in low oxygen

niches.

The maximum uptake of oxygen (VO2 max) can be used as a measure of

human fitness.

Conformers’ internal environment is dependent on external factors such as

temperature, salinity and pH.

Conformers may have low metabolic costs and narrow ecological niches.

Describe behavioural responses in conformers to maintain optimum metabolic

rate.

Regulators can control their internal environment, increasing their range of

ecological niches.

Regulation requires energy to achieve homeostasis.

Describe the process of negative feedback control and thermoregulation in

mammals including the role of the hypothalamus, nerves, effectors and skin.

State the importance of regulating temperature for optimal enzyme controlled

reaction rates and diffusion rates to maintain metabolism.



Multicellular Organisms Sub-Topic 2.6(b)

Animal Transport & Exchange Systems

Prior Learning

In mammals a transport system is required to deliver essential substances to cells and

take waste materials away from cells

In mammals, nutrients, oxygen and carbon dioxide are transported in the blood

The heart is made up of four chambers, the right and left atria and the right and left

ventricles

Valves which prevent the backflow of blood are located between the atria and ventricles

and also found in the pulmonary artery and aorta

Blood vessels associated with the heart include the aorta, vena cava, pulmonary

arteries, pulmonary veins and coronary arteries

Deoxygenated blood comes back to the heart from circulating around the body and

flows into the vena cava, then flows through the right atrium and right ventricle before

leaving the heart through the pulmonary artery to go to the lungs

In the lungs the blood becomes oxygenated and returns to the heart via the pulmonary

vein, then flows through the left atrium and left ventricle leaving the heart through the

aorta to circulate around the body



(2.3) Metabolic rate

Metabolism is the set of chemical reactions that happen in living organisms to

sustain life.

The quantity of energy consumed by an organism per unit of time is

called its metabolic rate.

Energy is generated by cells during aerobic respiration:

glucose + oxygen carbon dioxide + water + ENERGY

Metabolic rate can be measured as

The rate of energy production as heat

The rate at which an organism consumes oxygen

The rate at which an organism produces carbon dioxide

Metabolic rate can be measured using calorimeters

A calorimeter is a well insulated container containing a pipe through which water

flows. Heat generated by the organism causes a rise in temperature of the water in

the pipe. Measuring the temperature of the water entering and leaving the

calorimeter for a given period of time, allows the calculation of the organism’s

metabolic rate from the data collected.



Indirect calorimetry measures the respiration rate in an organism by

measuring O2 uptake or CO2 production.

Different types of organisms have different metabolic rates.

Use Torrance text book, chapter 10, to find out the metabolic rates of various

animals at rest.

Animal

animal group

Volume of oxygen consumed

(mm3g-1 body mass h-1)

The oxygen consumption is then used to calculate the basal metabolic rate

(BMR). This is a measure of the energy consumed by an organism when at rest.

Any increase in activity by the organism will use more energy in addition to the

BMR.

Label the diagram.

Use the space below to explain how a respirometer

works.



The energy needed by an organism can be broken down into 3 main

parts

1. BMR

2. Physical activity- the more activity, the higher the energy cost

3. The cost of digesting and processing food

Oxygen delivery

An organism’s metabolic rate will increase to meet an increasing demand for

energy.

Its rate of aerobic respiration will increase and consumption of oxygen will

increase as it is important that oxygen rapidly reaches all body cells.

Aerobic organisms with high metabolic rates have efficient transport

systems capable of delivering large supplies of oxygen to respiring cells.

Each vertebrate group has specific adaptations of the circulatory

system to cope with their own aerobic demands and metabolic rates.

Vertebrates use closed circulation systems – a muscular heart pumps

blood through a closed system of blood vessels.

http://www.google.co.uk/imgres?imgurl=http://images.clipartpanda.com/whatnot-clipart-circulatory.png&imgrefurl=http://imgkid.com/human-circulatory-system-simple.shtml&h=1600&w=1200&tbnid=9eb6hNwaAMXSvM:&zoom=1&q=human+closed+circulatory+system&docid=70zJ_xdsZulWNM&ei=q-wPVfjlCdLg7QaH3oDQBQ&tbm=isch&ved=0CBgQMygQMBA4ZA



(1) Circulatory systems

Fish

Using information from the power point presentation: Limitations

of this system are:

_____________________________________________________

_____________________________________________________

Amphibians and Reptiles

Using information from the power point presentation: Limitations of this system are:

____________________________________________________________________

____________________________________________________________________

____________________________________________________________________

Circulation and blood pressure

Blood travels though a two chamber pump in a single circuit from the heart to the gills and then on around the body. Since blood pressure decreases as the blood passes through the gills, body tissues receive blood under low pressure. Blood flow is aided by body movements during swimming.

Heart Atrium A single atrium receives deoxygenated blood from the body.

Ventricle A single ventricle pumps deoxygenated blood to the gills.


Three chamber, double cycle pump with one circulation loop pumping to the lungs and skin and another loop pumping to the body. Although blood loses pressure as it passes through the capillary beds, in the lungs and skin, the pressure increases again as it passes through the heart for a second time.

Heart Atria A right atrium receives deoxygenated blood from the body. A left atrium receives oxygenated blood from the lungs and skin.

Ventricle A single ventricle receives blood from both atria. Mixing of oxygenated and deoxygenated blood can take place but is reduced by internal ridges that divert deoxygenated blood from the right atrium towards the lungs and skin and oxygenated blood from the left atrium towards the rest of the body.



Mammals and Birds

Why is this kind of system essential in warm blooded animals?

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________


Four chambered double cycle pump. There is a double circuit with the right side of the heart pumping blood to the lungs and the left side pumping blood to the body. Pumping blood through the heart after it has been through the lungs ensures that the body tissues receive blood under high pressure.

Heart Atrium A right atrium receives deoxygenated blood from the body. A left atrium receives oxygenated blood from the lungs.

Ventricles A right ventricle pumps deoxygenated blood from the right atrium to the lungs. A left ventricle pumps oxygenated blood to the body. By having two ventricles, mixing of the oxygenated and deoxygenated blood is prevented. This is important to maintain the high metabolic rate required in these animals.



Oxygen Delivery

(2) Lung Systems

Amphibians

The lungs in amphibians are small balloon-like thin walled sacs.

The surface area available for diffusion is low as it is limited

only to the outer surface area. This means that the amount of

oxygen obtained through the amphibian lung is small. To ensure

they have enough oxygen to support their metabolic rate

amphibians exchange gases through their skin and mouth

cavity and only use their lungs during vigorous activity.

Reptiles

Reptiles are more active than amphibians and have a

greater metabolic oxygen demand. They have a basic

bronchiole system with alveoli clustered at the ends,

increasing surface area over which diffusion can take

place.

Mammals

Mammals have an even greater oxygen demand with the

evolution of regulated temperature. The bronchioles have many

branches leading to many clusters of alveoli which provide a

large surface area for diffusion. This enables large quantities

of oxygen needed for aerobic respiration to pass into the

bloodstream and be transported to metabolising tissues and

organs. Breathing movements of the lungs and diaphragm bring

about the emptying and filling of the lungs.



Birds

Birds are the most active of the vertebrate groups and need more oxygen

relative to their body size compared to all other vertebrates. In addition to their

lungs they possess several large air sacs that keep air flowing through the

lungs acting like bellows.

When a bird inhales air, its posterior air sacs fill with fresh air while its anterior

air sacs become filled with stale air from the lungs. When the bird exhales, the

fresh air passes from the posterior air sacs to the lungs and the stale air passes

from the anterior sacs to the external environment. Air is forced in one direction

preventing the mixing of inhaled and exhaled air and maximising the oxygen

content of the air and allows them to maintain a very high metabolic rate.

Physiological Adaptations of animals for low oxygen niches

The human body functions best at sea level where the concentration of oxygen in

the air is around 20%.

Read Torrance text book, chapter 10, then write a statement describing the how

the human body responds when a person moves to a high altitude and why this

response is important.

________________________________________________________

________________________________________________________



Case Study

Animal Adaptations to Survive Low Oxygen Niches.

You are going to research and write an article on organisms’ adaptations to

survive in low oxygen niches.

You will take on the role of an editor of a science magazine who is to write

an article about how vertebrates adapt to survive in low oxygen niches. You

must include information that explains the adaptations and any underlying

biology.

Oxygen Levels Over Geological Timescale.

The amount of oxygen in Earth’s atmosphere is determined by a wide range of physical and biological processes. The level of oxygen in the atmosphere has

fluctuated significantly until relatively recently in geological time.

The oxygen available for metabolism directly affects the energy available

in an organism and so affects the size of the organism that can be

sustained. Fossil records show that when oxygen levels rose to current levels of

around 20% many different groups of animals ‘suddenly’ increased in size as only

then was the oxygen level rich enough to maintain their metabolism. However, as

evolution continued eventually body size of terrestrial animals reached a maximum

determined by other limiting factors.

Read Torrance chapter 10 to find out what other factors might limit the size of a

terrestrial animal. Write a note about what you found out in the space below

___________________________________________________________________

Timescale

(years ago)

Oxygen level Organisms

~ 3.5 -2.45 billion Virtually none Very little present, simple archaea forms.

2.45-0.85 billion O2 produced but absorbed

into oxygen sinks

Micro-organisms. Evolution of

cyanobacteria which can photosynthesise

and produce oxygen

850 -300 million Free oxygen in

atmosphere (up to 35%)

Multicellular organisms evolve such as

invertebrates.

300 million - present Current levels ~20% Large biodiversity of organisms now

present. Biggest organisms are large

mammals.



Fitness and Maximum Oxygen Uptake

VO2 max is the volume of oxygen used per kilogram of body mass per minute

(ml/kg/min) while exercising at maximum capacity.

VO2 max can be used to measure fitness in humans.

The greater the VO2 max the greater the fitness of a person



(2.4) Metabolism in Conformers and Regulators

The ability of an organism to maintain its metabolic rate is affected by external

abiotic factors such as temperature, salinity and pH. Animals can be divided into

two groups: conformers and regulators.

(1) Conformers

Conformers are animals that allow their internal body conditions for a

particular factor to vary with the external environment.

The advantage to this way of life is that the animal’s metabolic costs are low as it

does not need to use up energy maintaining a stable internal environment. However,

the disadvantage is that they are restricted to a narrow range of ecological

niches and are less adaptable to environmental change. Such organisms may

employ behaviour responses to maintain their optimum metabolic rates.

Osmoconformers

Marine invertebrates such crabs, shrimp and jellyfish are

osmoconformers. Their body fluids are isotonic with their

environment. The solutes in their body tissues are equal to those

in their surroundings.

Thermoconformers

Lizards are thermoconformers. Their body temperature varies

with the temperature of the environment.

Read Torrance text book chapter 10 and from your findings describe how lizards use

a behavioural response to maintain their optimal metabolic rate.



(2) Regulators

Regulators are animals that use physiological mechanisms (homeostasis)

to maintain their internal body conditions at optimal levels.

The advantage of this way of life is that it allows the organism to increase the

range of possible ecological niches. However, the disadvantage is that it is

costly in terms of energy requirements as energy is consumed to maintain the

physiological mechanisms at a steady state.

On the graph below draw a line that would represent the internal environment of

i) a rigid regulator ii) a rigid conformer.



Summarise the key features of conformers and regulators in the table below.

Advantages

Disadvantages

Mechanisms used to control the

internal environment

Conformers

Regulators

What is our internal environment?

Complete the diagram below to show 3 aspects of the human internal environment

that need to be maintained at a steady state.

internal

environment



Physiological Homeostasis

Physiological homeostasis is the maintenance of the body’s internal

environment within certain tolerable limits despite changes in the body’s external

environment. To allow homeostasis there must be a corrective mechanism that

acts when any variable of the internal environment changes too much. Such a

mechanism uses negative feedback.

Aspects of the internal environment are monitored by receptor cells in the

monitoring centres of the body. Deviations away from the normal level (called the

norm or set point) are detected by receptor cells. These send out nerve or

hormonal messages which are received by effectors.

The effectors bring about a response which counteracts the original deviation

away from the norm to return the system back to its set point.

Thermoregulation

Animals vary in their ability to regulate their temperature. The process is best

developed in birds and mammals which are endothermic. Endotherms rely

entirely on heat which is produced internally as a by-product of their

metabolism.

Endotherms regulate body temperature within narrow limits, by balancing

heat production and heat loss. They are able to maintain their body

temperature at a relatively constant level independent of the temperature of the

external environment.

Ectotherms also produce metabolic heat but they are less able to retain it and

require external heat from the sun. They are unable to regulate their body

temperatures by physiological means. Ectotherms’ body temperature may

fluctuate considerably depending on the environmental temperature.



The Importance of Temperature Regulation

Maintaining an optimum temperature within the body is essential to ensure that

diffusion and all enzyme controlled reactions are working at an efficient

metabolic rate.

When body temperature is below the optimum temperature for enzyme function

metabolism is slow. Above the optimum, enzymes start to denature; the metabolism

slows down and eventually stops.

Temperature regulation is only possible if there is some sort of ‘thermostat’ which is

activated if the temperature varies from a fixed point

(the norm).

The hypothalamus is the body’s temperature monitoring centre. It acts like a

thermostat and is sensitive to nerve impulses that it receives from heat and cold

receptors (thermoreceptors) in the skin. These convey information to it about

the surface temperature of the body. In addition receptors (thermoreceptors) in the

hypothalamus detect changes in blood temperature which reflect changes in core

body temperature.

The thermoregulatory centre of the hypothalamus responds to this information by

sending nerve impulses to effector organs in the skin and body muscles. The

effectors bring about a response to return the temperature back to normal.



Warming-up Mechanisms (Too cold!)

Vasoconstriction (narrowing) of the arterioles in

the skin to reduce blood flow away from the skin

and so reduce heat-loss by radiation and

conduction from the blood.

Shivering to increase muscle activity and

generate heat.

Contraction of hair erector muscles causing

the hairs to be raised, so trapping a layer of insulating air to reduce heat

loss.

Little sweat is produced.

Increased metabolic rate to produce more heat.



Cooling-down Mechanisms (Too hot!)

Vasodilation (widening) of the blood vessels in

the skin to increase blood flow to the skin and

so promote heat-loss by radiation and

conduction from the blood.

No shivering.

Hair erector muscles are relaxed allowing body

hair to lie flat against the skin minimising the

insulating effect.

Increased activity of the sweat glands to release

sweat which evaporates using heat from the body to

do so, and so helps to lower body temperature.

Decreased metabolic rate to reduce heat

production.



Negative Feedback in Temperature Regulation

Using the information from the power point presentation complete the diagram

below to summarise negative feedback mechanism in temperature regulation.

Answer the following questions

Receptors

Type of Message

Effector

Corrective

Responses

Result

Heating up

mechanisms

Cooling down

mechanisms



1. Give the term used for animals which can control their internal temperature by negative feedback.

_______________________________________________________________

2. State the two ways that the hypothalamus obtains information about the

temperature of the body.

_______________________________________________________________

_______________________________________________________________

3. Name two effectors to which the hypothalamus sends nerve impulses in order

for them to respond and return body temperature back to normal.

_______________________________________________________________

_______________________________________________________________

4. Why is body temperature important in carrying out metabolic processes?

______________________________________________________

______________________________________________________



(2.3) Metabolic Rate (2.4) Metabolism in Conformers and Regulators

1 2 3

State that metabolic rate is the quantity of energy consumed by an organism per unit of time.

Metabolic rate can be measured as oxygen consumption per of unit time, carbon dioxide production per unit of time or energy production as heat per unit of time.

State that different types of organisms have different metabolic rates.

Compare the metabolic rate of different organisms.

Animals have various physiological adaptations to deliver oxygen to cells.

High metabolic rates require efficient delivery of oxygen to cells.

Describe the structure and circulation of the fish heart and lung structure.

Describe the structure and circulation of the amphibian and reptile heart and structure of the lungs.

Describe the structure and circulation in the mammalian and bird heart and structure of the lungs.

Describe physiological adaptations that animals have to survive in low oxygen niches.

The maximum uptake of oxygen (VO2 max) can be used as a measure of human fitness

Conformers’ internal environment is dependent on external factors such as temperature, salinity and pH.

Conformers may have low metabolic costs and narrow ecological niches.

Describe behavioural responses in conformers to maintain optimum metabolic rate.

Regulators can control their internal environment, increasing their range of ecological niches.

Regulation requires energy to achieve homeostasis.

Describe the process of negative feedback control and thermoregulation in mammals including the role of the hypothalamus, nerves, effectors and skin.

State the importance of regulating temperature for optimal enzyme controlled reactions rates and diffusion rates to maintain metabolism.

Complete:

Column 1 before your Unit assessment

Column 2 before your Prelim

Column 3 before your May exam

Higher Biology Unit 2: Metabolism and Survival (2.3 ... · Higher Biology Unit 2 Pupil Course Notes...

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