investigating aerobic respiration · investigating aerobic respiration ... faeces are collected in...

Dr Smith 19/09/2011

Credit Material in italics GDS 1

INVESTIGATING AEROBIC RESPIRATION

Need for Energy

Living cells are the site of a number of chemical reactions. Together these chemical reactions are called

metabolism. Some of these reactions release energy. Living cells need energy for:

Cell division e.g. growth & repair

Maintaining body temperature (birds & mammals)

Movement

Chemical reactions e.g. making enzymes, digesting food

RESPIRATION is the process by which cells release ENERGY from GLUCOSE. It happens in all

living cells (plant & animal) all the time.

Aerobic Respiration

Oxygen is required for aerobic respiration. Two waste products, water and carbon dioxide are

made.

Equation for aerobic respiration:

GLUCOSE + OXYGEN WATER + CARBON DIOXIDE + ENERGY

Reactants waste products useful product

The carbon dioxide released can be detected by

Turning limewater milky

Turning bicarbonate indicator from red to yellow

Aerobic respiration occurs in many small steps, each controlled by an enzyme. This allows the

energy to be released in small amounts.

Dr Smith 19/09/2011


The energy in food molecules such as glucose is CHEMICAL ENERGY. Green plants

capture LIGHT ENERGY and convert it into chemical energy in photosynthesis (Error!

Bookmark not defined.). Animals obtain their food from plants (Error! Bookmark not

defined.).

The quantity of energy contained in foods can be found by burning a measured mass of food

and using the heat energy released to heat a measured volume of water.

The energy content of different foods differs:

Fats contain TWICE as much energy as proteins or carbohydrates (e.g. glucose & starch)

Respirometers

A respirometer can be used to measure the rate of respiration

The use of respirometers depends on three factors:

The volume of oxygen used up is equal to

the volume of carbon dioxide produced

The carbon dioxide can be absorbed by a

chemical (e.g. soda lime, potassium

hydroxide) and so the uptake of oxygen is

seen as a drop in the volume of air in the

respirometer

There is no change in the temperature of the

apparatus. (changes in temperature cause

changes in the volume of gases!)

In the apparatus above, the taps are closed at the start of the experiment. As the oxygen is

removed the volume of air in the tube decreases and this sucks the coloured liquid up the tube

towards the earthworm’s tube.

Dr Smith 19/09/2011


The control should be a non respiring material (i.e. dead animal or glass beads) and of the

same volume as the respiring animal.

The syringe is used to return the volume back to its original level. In this way, the volume of

oxygen taken in can be measured and if the time taken to produce the change is known, the

rate of respiration (oxygen uptake per minute) can be calculated.

Energy release

During respiration some of the energy is released as heat energy. As a result in a confined

space the temperature of the surroundings is raised. The heat can be detected using an air

thermometer.

The heat released by the

respiring animal expands the air

in the tube and pushes the

coloured liquid. There is no

expansion in the control side.

Dr Smith 19/09/2011


ANIMAL SURVIVAL

THE NEED FOR FOOD

Food provides energy and raw materials for growth.

Food contains 3 types of food molecule:

Food Molecule

Use in Body

Carbohydrates: Source of energy

Fats Source of energy/ Store of energy/

Insulation Proteins Raw materials for growth & repair

Structure of Food Molecules:

carbon sugar give starch.

to

Polymers (long chains)

to give

cellulose

nitrogen

amino

proteins.

acid

20

hydrogen

fatty

glycerol

acid

to form a fat molecule

fatty

acid

units glycerol

Dr Smith 19/09/2011


Parts of the Mammalian Alimentary Canal (gut)

Digestion

Food is made of large particles containing large, insoluble molecules. Large, insoluble

molecules cannot pass across the wall of the intestine. Food molecules can only be absorbed

if they are soluble.

Digestion is the process in which large, insoluble food particles are broken down into small soluble molecules,

which can pass across the wall of the small intestine.

Mechanical Digestion

This when the teeth are used to break large pieces of food into smaller pieces. This increases

the surface area of the food on which enzymes (Error! Bookmark not defined.) can act.

Teeth are specially adapted to suit the diet of the organisms:

Herbivore Animal that eats only plants, e.g. Cow, sheep

Carnivore Animal that eats only meat (other animals) e.g. Lion, dog

Omnivore Animal that eats both plants and animals e.g. human, bear.

Dr Smith 19/09/2011


(HERBIVORES)

(CARNIVORES)

(OMNIVORES)

Dr Smith 19/09/2011


Chemical Digestion

Chemical digestion is carried out by enzymes in digestive juices. They are:

Digestive Juice

Site of Production Main Enzymes

Saliva Salivary Glands Salivary Amylase

Gastric juice Stomach Pepsin

Bile Liver (stored in gall bladder) Bile is not an enzyme, but helps in fat digestion.

Pancreatic juice

Pancreas (secreted into small intestine)

Pancreatic amylase; Lipase; Protease

Intestinal juice Wall of small intestine Proteases

Action of digestive enzymes

A digestive enzyme is a chemical which speeds up the breakdown of food

ENZYME SITE PRODUCED SUBSTRATE PRODUCT

Amylase Saliva (salivary amylase) Pancreas (into small intestine)

STARCH MALTOSE

Lipase Pancreas (into small intestine) FATS FATTY ACID & GLYCEROL

Proteases e.g. pepsin—stomach e.g. peptidase—pancreas (into small intestine)

PROTEINS PEPTIDES OR AMINO ACIDS

Structure of the Small Intestine

The small intestine is where all soluble food molecules are absorbed. It is adapted to fulfil

this role:

It has a large surface area for absorption because:

It is very long

Its lining has finger-like projections (villi)

It can rapidly absorb digested food molecules by

diffusion because:

The lining is very thin

Lots of blood vessels carry away absorbed food

Part of small

intestine

One villus

Finger-like projections—called villi

Thin surface layer

Blood capillary

lacteal

Dr Smith 19/09/2011


Absorption of Digested Foods

Feature Function

Thin lining Allows rapid diffusion of products of digestion

Blood capillaries Absorption and transport of glucose and amino

acids

Lacteal Absorption of products of fat digestion

Lymph vessels Transports fats from villus

Role of the Large Intestine

- Reabsorption of water and elimination of undigested remains (FAECES)

Faeces are collected in the rectum and then passed out through the anus.

Movement of Food along the Gut

PERISTALSIS = contractions of the muscular

wall of the gut pushing food along .

MECHANISM OF PERISTALSIS

Muscles behind contract

Muscles in front relax

A wave of this muscular contraction and relaxation

sweeps down the gut, pushing the food ahead of it.

STOMACH CONTRACTIONS: Muscles in the stomach wall contract and relax, helping churn the food

with digestive juices, speeding up the digestion of food.

gut

Muscles behind

contract

Muscles in front relax

Dr Smith 19/09/2011


REPRODUCTION

Asexual reproduction - one parent, no sex organs, no sex cells

Sexual reproduction - two parents, sex organs, sex cells (gametes) are made

Sex cells:

Sperm Egg

Male sex cell Female sex cell

Head nucleus and tail Nucleus and food store

Can swim Cannot swim

Small Large Sperm are attracted to egg cells

Fertilisation:

The nucleus of the male sex cell joins with the nucleus of the female sex cell

Fertilisation can be internal or external. External fertilisation takes place outside the body and

internal fertilisation occurs inside the female’s body. Sperm need to swim to the egg so

external fertilisation must take place in water. In internal fertilisation the sperm swim in the

semen. Internal fertilisation allows land living animals to reproduce without returning to the water.

External Fertilisation e.g trout, frog

Produce many sex cells*

Release sex cells into water

Have courtship rituals or

synchronise release of sex cells*

* This increases the chances of an egg

being fertilised.

Dr Smith 19/09/2011


Dr Smith 19/09/2011


Internal Fertilisation e.g. human, and other

mammals

Produce few sex cells (especially eggs)

Male places sperm inside the female’s body. The

egg is fertilised in the OVIDUCT.

Immediately following fertilisation, a

FERTILISATION MEMBRANE forms around

the egg. This prevents a second sperm from entering the

egg. If a second sperm was to penetrate the egg, the

resulting zygote would have the wrong number of sperm

and so would not develop normally (see S4 notes).

The fertilised egg (ZYGOTE) develops into an

EMBRYO. It develops in the uterus.

Feeding/ Caring for the young

Fish

A fertilised fish egg consists of:

An embryo

A food store

A protective, flexible covering (jelly/ membrane)

A newly hatched trout

Feeds from yolk in the yolk sac

Receives no parental care and so looks after itself

Finds food for itself after its yolk sac is used up

Dr Smith 19/09/2011


Mammalian Egg

The egg is fertilised in the oviduct

As it travels down the oviduct to the uterus, it divides many times, forming a ball of cells

The ball of cells implants into the spongy wall of the uterus

Here the embryo develops a placenta. It is connected to the placenta by the umbilical

cord

The embryo grows inside a sac called the AMNION, filled with amniotic fluid. This

supports the embryo and protects it from bumps

STRUCTURE & FUNCTION OF THE PLACENTA

An embryo mammal develops a PLACENTA which is a flattened cushion-like organ.

A long twisted coil of blood vessel, called the umbilical cord, stretches from the embryo to the placenta. In the

placenta, the blood of the mother and embryo pass very close to each other but do not actually mix.

Passes from mother to embryo Passes from embryo to mother

Oxygen

Glucose, Amino Acid (food)

Carbon Dioxide

Urea (& other wastes)

Harmful substances (e.g. drugs, alcohol, nicotine)

Mammals are born through the vagina. Once born, it suckles milk from its mother.

Mammals receive a large amount of care and protection from their parents.

Number of eggs and chances of survival

The more care offspring receive, the more likely they will survive to reproduce, so the fewer are produced e.g.

turtles lay many eggs, bury them & leave.

Many young lost due to predation.

polar bears produce two or three young, feed and protect them for around two years.

Most of them survive

Animals with INTERNAL fertilisation and much care of the young, need to produce very few eggs, as each

has a high chance of survival

Animals with EXTERNAL fertilisation and no parental care need to produce huige numbers of eggs as each

has such a low chance of survival .

Dr Smith 19/09/2011


WATER & WASTE

Our bodies contain much water

This amount needs to be kept constant if we are to remain healthy

Water is lost or gained in a variety of ways

Daily water Gain Daily water loss

DRINK

FOOD

CHEMICAL REACTIONS e.g

aerobic respiration

SWEAT BREATH

URINE

FAECES

WATER GAIN = WATER LOSS

The Human Urinary System

The functions of these parts of the urinary system are:

Part Function

Renal artery Carries blood TO the kidney

Renal vein Carries blood FROM the kidney

Kidney Regulates water

Removes waste (urea) from the blood

Ureter Carries urine from kidney to bladder

Bladder Stores urine

Dr Smith 19/09/2011


The kidneys

are the main organs for regulating water content of blood

change the VOLUME & CONCENTRATION of URINE

remove poisonous waste, called urea*, from the blood

* Urea is produced from the breakdown of amino acids. This happens in the liver. The urea is then

transported, dissolved in the plasma of the blood to the kidney, where it is excreted.

How the Kidney works

The kidneys function by:

FILTRATION

REABSORPTION

FILTRATION occurs in the glomerulus, both poisonous and useful substances are filtered from the blood.

The glomerular filtrate is captured by the Bowman’s Capsule, and moves into the tubule.

In the tubule, useful substances, glucose, most of the water are reabsorbed, back into the blood. They go into the

blood capillary running alongside the tubule.

Dr Smith 19/09/2011


The role of ADH in regulating Water Balance

ADH (Anti diuretic hormone)

Hormone, made of protein

Produced in the pituitary gland (at base of the brain)

Increases permeability of tubule to water

Causes more water to be reabsorbed (reduces volume/ increases concentration of urine)

If there is too little water in the blood*, the brain detects this and causes the pituitary gland to produce more

ADH. This causes the kidney to reabsorb more water from the glomerular filtrate and so reduces the volume of

urine produced. The concentration of urine is increased.

If there is too much water in the blood, the brain senses this and causes the pituitary gland to produce less

ADH. This causes the kidney tubule to reabsorb less water. The volume of urine is produced increases, the

concentration decreases.

* Too little water in the blood is caused by sweating a lot, not drinking enough or eating lots

of salt.

Dr Smith 19/09/2011


If the kidneys become damaged (diseases, accident) then toxic wastes build up in the body.

This is fatal if left untreated. 2 treatments are possible.

Kidney dialysis on a kidney machine

Kidney transplant

In the kidney machine, only harmful substances are filtered out of the blood, useful

substances stay in the blood, so there is no need fro reabsorption.

Comparison of Machines and Transplants

Benefits Drawbacks

Kidney Machine Prevent death Expensive

Restrictive (dialysis takes several hours, 2

or 3 times a week)

Transplant Allows a normal life to be lead Donor shortage

Possible rejection of kidney – so drugs

taken rest of life

Dr Smith 19/09/2011


RESPONDING TO THE ENVIRONMENT

Animals need to respond to changes in their environment to ensure their survival e.g.

Animals Stimulus Response Survival Value

Woodlouse Dampness Move towards it (high humidity) Prevent drying out

Flatworms Extract of

liver

Moves towards it Source of food

Earthworms Light Moves away from it Escapes predation/

drying out

Euglena Light Moves towards it Euglena

photosynthesises

Rhythmical Behaviour

Animal behaviour shows regular changes triggered by environmental changes. e.g. Light &

dark, long/ short days. Migration in geese is an annual rhythmical behaviour triggered by

changes in daylength. Activity in shore crabs is a TIDAL rhythm triggered by tidal

movements.

The main features of rhythmical behaviour are:

Regular - occurs at fixed intervals

Triggered - started by an external stimulus

Persistent - continues even if the trigger stimulus is absent (e.g. shore crabs show behaviour patterns related to tidal changes even when placed in a non tidal tank

Rhythmical behaviour helps animals exploit regular changes in their environment. e.g. it makes sure

They have their young at a time when food is plentiful and weather is fine (daylength triggers mating in deer,

sheep & blue tits). This increases the chances of survival.

For shore crabs, being active during specific periods of the tide cycle allows them to obtain food as the tide comes

in and escape predation by hiding when the tide is receding.

Dr Smith 19/09/2011


PROBLEM SOLVING

Percentage Calculations. PERCENTAGE CALCULATIONS

3 Types of percentage calculation can be asked:

Percentage change (increase or decrease):

If the answer is negative the factor has decreased, if it is positive the factor has increased

e.g. Calculate the percentage change in blood flow to the skeletal muscles during exercise, if it rises from 10 l/min to 30l /min.

Percentage change = 30-10 ÷ 10 X 100 = 20÷10 X 100 = 200% change (increase).

Percentage of: This asks what percentage a subset is of the total

e.g. What percent of the whole population has blood group AB?

Total = 24 + 45 + 33 + 86 = 188

Subset = 33

Percentage = 33 ÷ 188 X 100 = 17.6%% How many, if the percentage is already given:

e.g. If 20% of a class of 40 have blue eyes, how many of the class has blue eyes?

Total =40

Number = 40 X 20 ÷ 100

= 800 ÷ 100 = 8

Percentage change = End value—start value

Start value

X 100

To find the

change

To change to a

percentage

STEP 1 - Find the START Value (in the question)

STEP 3 - FIND OUT HOW MUCH IT HAS CHANGED

(use a calculator!!!!!): END VALUE – START VALUE

STEP 2 - Find the END value (in the question)

STEP 4 - Divide this answer by the START VALUE

STEP 5 - Multiply that answer by 100

STEP 1 - Find the START Value (in the question)

STEP 3 - FIND OUT HOW MUCH IT HAS CHANGED

(use a calculator!!!!!): END VALUE – START VALUE

STEP 2 - Find the END value (in the question)

STEP 4 - Divide this answer by the START VALUE

STEP 5 - Multiply that answer by 100

Percentage of = Size of subset

Total To change to a

percentage X100

To calculate the proportion the sub-

set forms of the total

Number = Total X Percentage

100

Blood Group A B AB O

Number 24 45 33 86

Dr Smith 19/09/2011


Ratios

A ratio is a way of showing the relationship between two or more values.

For example a forest contains two types of deer, Roe deer and Fallow deer. The deer are counted and

360 Roe deer are found, but only 120 Fallow deer are present. To express this as a ratio a number of

steps can carried out.

1. Try to divide the large number by the small number 360 : 120 each by 120

3:1 this is the simplest whole number ratio.

Second example.

The head teacher wishes to know the ratio of male staff to female staff in the school. There are 32

male staff and 56 female staff

1. Try to divide the large number by the small number 32: 56 each by 32

1:1.75, not a whole number ratio so move to next step

2. Divide both sides by the largest number which goes in evenly,

32:56 each by 4

8: 14 each by 2

4:7 This is the simplest whole number

ratio, the two numbers cannot be divided evenly by the same number!

Third example

The EU fishery minister suggested that the North Sea contained very little cod, but much more

herring. The survey shows that there were 175 cod, and 1,260 herring. What is the ratio of cod:

herring.

1. Try to divide the large number by the small number 175 : 1260 each by 175

7.2:1, not a whole number so move to next step

2.Find a number that will divide evenly into both sides (the same number for each side)

175: 1260 each by 5

35:252 can they be divided again?

35:252 each by 7

5:36 This is the simplest whole

number ratio, the two numbers cannot be divided evenly by the same number!

Dr Smith 19/09/2011


Chemical Tests TESTS

pH Scale (Acidity/ Alkalinity)

The pH Scale gives a measure of how acidic or alkaline a solution is:

pH is measured using pH indictor or paper

The pH falls (becomes more acidic) when fats are broken down to fatty acids (& glycerol), or protein

are broken down (to give amino acids)

Carbon Dioxide

Carbon dioxide is the gas used up in photosynthesis and produced in aerobic respiration in animals and

plants (along with water) and in anaerobic respiration in plants (along with alcohol). In experiments it

can be absorbed by soda lime or potassium hydroxide.

Carbon dioxide turns limewater milky.

Bicarbonate indicator can be used to tell how much carbon dioxide is present

Experimental Design

In a scientific experiment a test is only fair if only one variable factor has been changed at a time.

Examples of variable factors are time, lengths, volumes, weights and concentrations. If more than is

changed between experiments the test is not fair. A fair test is also a VALID test.

Experiments are repeated to make them more RELIABLE or REPRESENTATIVE. To make an

experiment more accurate better equipment must be used e.g. a more accurate balance or replace a ruler having centimetre divisions with one having millimetre divisions.

Food Tests

pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14

COLOUR of

pH indicator RED ORANG YELLOW

GR

EE BLUE PURPLE

Carbon Dioxide Zero Normal (0.03% High

Colour of Bicarbonate Indicator Purple Red Yellow

Food Type Reagent Procedure Positive result

Glucose (sugar) Benedict’s Heat with sample at 95°C Turns from blue to orange

Starch Iodine Add to sample Turns from orange to blue/

black

Protein Biuret Heat with sample Turns from to violet

Fats Alcohol and

water

Shake with sample. Solution goes cloudy

one is

Dr Smith 19/09/2011


Charts/Graphs CHARTS

In Biology two types of chart are used: the BAR chart and the LINE GRAPH

Usually a question tells you which to draw.

BAR CHART

When data concerns the numbers in various groups, then a bar chart is used

Label; axes names and units (if any)

copy the column headings. The first set of information goes on the horizontal axis, the

second on the vertical axis.

Devise a scale (divide the axis up evenly).

Find the highest value in your data. 37

Count the number of large squares on your vertical axis 8

Divide the highest value by the number of squares, 37/8 = 4.625

round your answer up to the nearest easy* number. i.e. 5 Each large square is worth 5 *easy numbers are usually 1, 2, 5, 10, 50, 100 etc.

Draw the bars (you should make each bar the same width and leave a gap between the bars (you won’t

lose marks if you don’t)

LINE GRAPH Line graphs are used when both sets of data are numbers. A scale must be used on both axes.

Label axes by copying the column headings (first 1st—horizontal, 2nd column—vertical)

Devise scales for both axes

Horizontal 50/10 = Each big box is worth 5 ºC

Vertical 74/8 = 9.25, Each big box is worth 10%

Plot the points and join with a straight line (Only join 0,0 if that point is in the data)

Colour of Flower Number

RED 37

BLUE 15

YELLOW 7

WHITE 3

GREEN 24 Nu

mber

Colour of Flower

40

35 30

25

20 15

10 5

0

RE

D

BL

UE

YE

LL

OW

WH

ITE

GR

EE

N

Temperature (ºC) Germination (%)

0 7

10 24

20 59

30 74

40 37

50 2

Ger

min

atio

n (

%)

Temperature (ºC)

80

70 60

50

40 30

20 10

0

0 10 20 30 40 50

Dr Smith 19/09/2011

ADH Hormone which regulates water

Aerobic respiration chemical reaction to release energy which requires oxygen

Amino acid Basic unit of protein molecule

Amnotic sac Membrane surrounding the developing foetus

Amylase Enzyme which breaks down starch into simple sugars

Anus Opening through which faeces are ejected

Bowman's capsule End of the kidney tubule which collects the filtrate

Canine Tooth used for ripping and tearing

Carbohydrate Chemical containing carbon, hydrogen and oxygen

Carnivore Meat-eater

Collecting duct Tube which takes urine from the tubules to the ureter

Fat Chemical containing carbon, hydrogen and oxygen

Fatty acid /Glycerol Basic units of fats

Fertilisation Fusion of an egg and a sperm cell

Gall bladder Stores bile

Glomerulus Knot of capillary blood vessels

Herbivore Plant eater

Incisor Tooth used for cutting

Lacteal Small lymph vessel in the villus which absorbs the products of fat digestion

Large intestine where water is absorbed

Lipase An enzyme which breaks down fat into fatty acid and glycerol

Metabolism all of the chemical activity taking place within an organism

Molar/Premolar Tooth used for grinding and chewing

Nephron Kidney filtration unit

Oesophagus (gullet) Connects mouth to stomach

Omnivore Eats plants and meat

Ovary Site of production of ova (eggs)

Oviduct Tube which carries the ova; site of fertilisation

Ovum (egg) Female gamete

Pancreas Makes digestive juices containing enzymes

Penis Organ for transferring sperm into the female

Peristalsis Muscular contractions which move food through the intestines

Placenta Region of the uterus wall where materials are exchanged

Protease An enzyme which breaks down protein into amino acids

Protein Chemical containing carbon, hydrogen, oxygen and nitrogen

Rectum Area of bowel for temporary storage of waste

Renal artery Blood vessel carrying blood to the kidney

Renal vein Blood vessel carrying blood away from the kidney

Rhythmical Behaviour shown on a regular, predictable pattern

Salivary glands Site of saliva production

Small intestine Site of absorption of products of digestion

Sperm Male gamete

Stimulus Change in the environment

Stomach Main site of chemical digestion

Dr Smith 19/09/2011

Testes Site of sperm production

Urea Waste product from the breakdown of amino acids

Ureter Tube which carries urine to bladder

Urethra Tube which carries urine from bladder to outside the body

Uterus Organ in which the foetus develops

Vagina Organ in which sperm are deposited

Villus Finger-like fold in the wall of the small intestine

Yolk sac Food store used by fish embryo

Zygote Fertilised egg

investigating aerobic respiration · investigating aerobic respiration ... faeces are collected in...

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