Biology F214

Front 1

Define stimulus

Back 1

Any change in environment that causes a response

Front 2

Define response

Back 2

A change in behaviour or physiology as a result of a change in environment

Front 3

What are the features of a good communication system?

Back 3

-Whole body is included

-Specific response

-Rapid response

-Short term and long term responses

Front 4

What are the features of the hormonal communication system?

Back 4

-Slow

-Travels in blood

-Chemical message

-Longer lasting response

Front 5

What are the features of the nervous communication system?

Back 5

-Fast

-Travels in nerves and neurones

-Electrical message

-Shorter response

Front 6

Define negative feedback

Back 6

The reversal of a change in the internal environment, to return to a steady state

Front 7

Define positive feedback

Back 7

The process that increases any change detected by the receptors- tending to be harmful

Front 8

Define homeostasis

Back 8

The maintenance of the internal environment in a constant state despite external changes

Front 9

Give an example of where and how negative feedback is used

Back 9

Body temperature- shivering when temp. is too low to increase temp., sweating when temp. is to high to reduce temp.

Front 10

Give an example of where and how positive feedback is used

Back 10

Body temperature- enzymes stop working at low temperatures, so less energy is released by their action, which decreases the temperature even further, causing hypothermia

Front 11

What body conditions are controlled by homeostasis?

Back 11

-Blood temperature

-Blood glucose concentration

-Blood salt concentration

-Water potential of the blood

-Blood pressure

-Carbon dioxide concentration

Front 12

Describe the negative feedback loop

Back 12

Optimum conditions> Change from optimum conditions> Receptor detects the change> Communication system informs effector> Effector reacts to reverse the change> Return to optimum conditions

Front 13

Describe the positive feedback loop

Back 13

Optimum conditions> Change from optimum conditions> Receptor detects the change> Communication system informs effector> Effector reacts to increase the change> Receptor detects the change...

Front 14

What is the function of a motor neurone?

Back 14

Carry the action potential from the CNS to an effector

Front 15

What is the function of a sensory neurone?

Back 15

Carry the action potential from a sensory receptor to the CNS

Front 16

what is the difference between motor and sensory neurones ?

Back 16

motor neorones

- cell body found in the CNS

-Long axon, no dendron but there are dendrites on cell body

sensory neourones

- cell body just outside the CNS

-Short axon, long dendron

Front 17

What causes the cell membrane to be polarised at resting potential?

Back 17

-Sodium/potassium pump actively pumps 3 NA+ for every 2 K+ in

Anions in cytoplasm

Some K+ channels are open so K+ diffuse out

Front 18

What causes the initial depolarisation of the membrane in the propagation of an action potential?

Back 18

A stimulus causes an energy change which causes the sodium ion channels to open, so sodium ions diffuse into the cell

Front 19

What is an initial depolarisation of the membrane in the propogation of an action potential called?

Back 19

Generator potential

Front 20

Describe what happens at threshold potential in the generation of a nerve impulse

Back 20

When -50mv is reached, voltage gated Na+ channels open, and Na+ ions diffuse in rapidly down a concentration gradient

Front 21

Describe how local currents are set up and how an action potential is passed along a neurone

Back 21

1. Na+ channels open and Na+ ions diffuse in down concentration gradient

2. Na+ concentration increases at site of channel

3. Na+ diffuses sideways along axon due to concentration gradient

4. Creates a local current

5. Voltage gated ion channels further along the axon open

6. Na+ ions enter neurone down a concentration gradient

7. New action potential is achieved further down the axon

Front 22

What is a local current?

Back 22

Movement of charged ions

Front 23

What happens at repolarisation step in the generation of a nerve impulse?

Back 23

Na+ channels close and K+ channels open, K+ diffuses out down concentration gradient

The potential difference inside the neurone is returned to negative

Front 24

What happens at the hyperpolarisation step in the generation of a nerve impulse?

Back 24

Potential difference overshoots slightly making inside more negative than before- this ensures no action potential is possible so it only moves forwards. Called the refractory period.

Potential difference is then restored by the Na+/K+ pump

Front 25

What is saltatory conduction?

Back 25

The way in which an action potential appears to jump from node to node because they can only be generated at the nodes of ranvier

Front 26

What are olfactory cells?

Back 26

Cells that detect chemicals, found in the nasal cavity

Front 27

What are proprioceptors?

Back 27

Muscle spindles which give you an awareness of your body and give you a sense of which muscles are contracting at any time

Front 28

What's the difference between myelinated and non-myelinated neurones?

Back 28

Myelinated neurones have Schwann cells wrapped around the neurone, which insulate it and increase the speed of conduction.

Front 29

outline the roles of synapse

Back 29

>ensures movement of , impulse / action potential , in one direction (only)

>integration or one neurone can transmit impulses to many neurones

>summation

> filters out , ‘background’ / low level , stimuli

> acclimatisation

>prevents continuous stimulation of neurones > permits , memory / learning and conscious thought

Front 30

Describe what happens in a presynaptic neurone to cause acetylcholine to be released

Back 30

-Action potential arrives at the neurone

-Voltage gated calcium (Ca+) ion channels open

-Ca+ diffuses into presynaptic neurone

-Ca+ ions cause synaptic vesicles of acetylcholine to fuse with with presynaptic membrane

-Acetylcholine is released by exocytosis

Front 31

Describe how acetylcholine causes an action potential to be produced in a postsynaptic neurone

Back 31

-Acetylcholine binds to receptors on postsynaptic membrane which are situated on sodium ion channels

-Causes sodium channels to open

-Triggers depolarisation

-An action potential is created

Front 32

What happens to the acetylcholine that isn't taken up by the postsynaptic neurone?

Back 32

It is broken down into ethanoic acid and choline by an enzyme called acetylcholinesterase. The ethanoic acid and choline are taken up by the presynaptic membrane and converted back into acetylcholine using energy from many mitochondria

Front 33

What is the difference between temporal and spatial summation?

Back 33

Temporal is the summation of many smaller action potentials in one neurone to produce one large action potential in the postsynaptic neurone

Spatial is the summation of many smaller action potentials in many neurones to produce one large action potential in the postsynaptic neurone

Front 34

What are the differences between the nervous and endocrine systems?

Back 34

Nervous- uses neurones and synapses

Endocrine- uses blood

Nervous- specific pathway for specific response

Endocrine- general pathway for specific response

Nervous- electrical and chemical signal

Endocrine- chemical signal

Nervous- quicker and short duration

Endocrine- slower and long duration

Front 35

What are endocrine glands?

Give some examples

Back 35

Ductless glands that consist of a group of cells that secrete a hormone straight into the blood

e.g. pituitary gland, ovaries, testes, adrenal gland

Front 36

What are exocrine glands?

Give some examples

Back 36

Ducts which release larger molecules such as enymes or sweat, not directly into the blood

e.g. salivary glands, sweat glands

Front 37

What are the two types of hormones and some information about each type?

Back 37

Protein and peptide homones- insoluble, so have to bind to a receptor and have a secondary messenger inside the cell. e.g. insulin, glucagon, adrenaline

Steroid hormones- soluble, so can enter the cell and have a direct effect on the DNA in the nucleus e.g. oestrogen, testosterone

Front 38

How does adrenaline cause its effects on cells?

Back 38

It is unable to enter the target cells so it binds to a complementary receptor on the cell surface membrane. This receptor is associated with the enzyme adenyl cyclase which is inside the cell, and is activated when adrenaline binds. Adenyl cyclase converts ATP to cAMP, which causes enzymes in the cell to become activated.

Front 39

Where is adrenaline manufactured?

Back 39

The adrenal medulla

Front 40

What are the effects of adrenaline?

Back 40

Relaxes smooth muscle in bronchioles

Increases stroke volume and heart rate

Vasoconstriction

Stimulates conversion of glycogen to glucose

Dilates pupils

Improves mental awareness

Front 41

How does relaxing smooth muscle in the bronchioles prepare you for activity?

Back 41

Widens airways which allows more airflow and increases O2 intake and CO2 expulsion

Front 42

What is manufactured in the adrenal cortex?

Back 42

Steroid hormones such as mineralocorticoids (ion monitoring) and glucocorticoids (control metabolism of carbs and proteins)

Front 43

Describe the exocrine functions of the pancreas

Back 43

Secretes enzymes; cells arranged around tiny tubules manufacture and secrete the enzymes into the tubules when stimulated by a hormone or a nerve impulse. The tiny tubules join together to form the pancreatic duct, which carries to (digestive) fluid to the duodenum

Front 44

What is contained in the digestive fluid from the pancreatic duct?

Back 44

Enzymes: amylase, trypsinogen, lipase

Sodium hydrogencarbonate to neutralise stomach acid

Front 45

Describe the endocrine functions of the pancreas

Back 45

Islets of Langerhans have alpha and beta cells which respectively manufacture and secrete glucagon and insulin directly into the blood

Front 46

How are alpha and beta cells in the Islets of Langerhans specialised?

Back 46

-Lots of ribosomes and RER for protein synthesis

-Lots of golgi apparatus for protein processing and packaging

-Lots of secretory vesicles to transport the hormone

-Many mitochondria to supply ATP for exocytosis

Front 47

How is the concentration of blood glucose regulated ? mark scheme answer

Back 47

beta cells / alpha cells / receptors , detect , change / increased / decreased ,in blood glucose (concentration)

;2 ) if high(er) glucose (concentration) , beta , cells (in pancreas) release insulin

3) (increased) uptake of glucose by ,liver / muscle / effector , cells ;

4) enters through glucose transport proteins (in cell surface membrane) ;

5) glucose converted to glycogen / (glycogenesis );

6) increased (use of glucose in) , respiration / ATP production ;

7) if low(er) glucose (concentration) , alpha /  , (in pancreas) cells release glucagon ;

8 (increased) conversion of glycogen to glucose / glycogenolysis ;

9 (increased) conversion of other compounds(amino acids / lipids) to glucose / gluconeogenesis ;

10 glucose leaves cells , by facilitated diffusion / through glucose channels ;

Front 48

What is the sequence of events if blood glucose concentration is too high?

Back 48

Beta cells detect the change and secrete insulin directly into the blood

Target cells on the liver (hepatocytes) and some other body cells have complementary receptors which the insulin molecule binds to

Activates adenyl cyclase inside the cells which causes the conversion of ATP to cAMP, which activates a series of enzyme controlled reactions inside the cell

Front 49

How does insulin reduce blood glucose concentration?

Back 49

Causes more glucose channels in the cell surface membrane to open

More glucose diffuses into the cells down a concentration gradient

Glucoes is converted into glycogen- glycogenesis

More glucose is converted into fats

More glucose is used in respiration

Front 50

What is the sequence of events if blood glucose concentration is too low?

Back 50

Alpha cells detect low blood glucose concentration and secrete glucagon

Target cells on the liver (hepatocytes) have a receptor which is complementary to glucagon, allows it to bind

Causes adenyl cyclase to be activated inside the cells, which leads to the conversion of ATP to cAMP and a series of enzyme controlled reactions inside the cell

Front 51

How does glucagon increase blood glucose concentration?

Back 51

Stored glycogen is broken down by hydrolysis to glucose (glycogenolysis)

Causes more fatty acids to be used in respiration

Causes the conversion of amino acids and fats into glucose (gluconeogenesis)

Glucose leaves cells by facilitated diffusion through glucose channels into the blood

Front 52

Describe how insulin is released from a beta cell

Back 52

High blood glucose concentration causes glucose to diffuse into the cell

Glucose is metabolised to produce ATP

The ATP causes potassium ion channels in the beta cell's cell surface membrane to close

Causes a buildup of potassium ions which makes the cell less negative inside

Change in p.d. causes calcium ion channels to open

Calcium ions which enter the cell cause the vesicles of insulin to fuse with the cell membrane, releasing insulin by exocytosis.

Front 53

What are the names of the two nerves that can alter heart rate?

Back 53

Vagus nerve can slow down the heart rate

Accelerator nerve can increase heart rate

Front 54

How is high blood pressure detected?

Back 54

Carotid sinus in the carotid artery has stretch receptors which detect the stretching of the arteries to accommodate a high blood pressure

Front 55

How is a high blood CO2 concentration detected?

Back 55

Chemoreceptors in arteries can detect the lowered pH from increased CO2

Front 56

What is the stroke volume?

Back 56

The volume of blood pumped per beat

Front 57

What is the medulla oblongata?

Back 57

A region at the base of the brain which coordinates the unconcious functions of the body e.g. breathing rate and heart rate

Front 58

Why is ATP made in respiration?

Back 58

It releases more energy when it is broken down than it requires to be made

Front 59

Describe the steps involved in the ATP cycle

Back 59

ATP is hydrolysed to ADP and Pi. This releases energy which becomes available to cells.

Energy from respiration is used to remake ATP in a condensation reaction, aided by the enzyme ATP synthase. To do this, ADP is phosphorylated which transfers energy to the ATP molecule.

ATP is hydrolysed......

Front 60

What is an anabolic reaction?

Back 60

A metabolic reaction that builds large molecules

Front 61

What is a catabolic reaction?

Back 61

A metabolic reaction that breaks large molecules into smaller ones

Front 62

How is energy used in the activation of chemicals?

Back 62

Energy is required for phosphorylation at the beginning of respiration so that it is more unstable and can be broken down to release energy

Front 63

What are photoautotrophs?

Back 63

Organisms that use light energy in photosynthesis to make large, organic molecules that contain chemical potential energy

Front 64

How much energy is released when ATP is hydrolysed to ADP and Pi?

Back 64

30.6 KJ per mol

Front 65

How much energy is released when ADP is hydrolysed to AMP and Pi?

Back 65

30.6 KJ per mol

Front 66

How much energy is released when AMP is hydrolysed to Adenosine and Pi?

Back 66

14.2KJ per mol

Front 67

What is a co-enzyme?

Back 67

An organic non-protein molecule that helps an enzyme to catalyse a reaction

Front 68

Why are coenzymes needed in respiration?

Back 68

Enzymes are not good at catalysing oxidation or reduction reactions so coenzymes are needed to carry out the oxidation reactions in respiration. The coenzymes can transport hydrogen atoms for use in reduction.

Front 69

What is the structure of NAD?

Back 69

2 linked nucleotides. The nucleotide contains the nitrogenous base adenine, and the other contains a nicotinamide ring. The two nucelotides are joined by the 2 phosphate groups.

Front 70

Why is NAD often called a nucleic acid derivative?

Back 70

It contains phosphoryl groups, adenine and ribose sugar which are all found in RNA.

Front 71

What is CoA made out of?

Back 71

amino acid- cysteine

patothenic acid- a B group vitamin

3 phosphoryl groups

adenosine- nitrogenous base adenine with a ribose sugar

Front 72

Why is there not much NAD or CoA in cells?

Back 72

They are recycled and can be regenerated

Front 73

Who might become deficient in NAD? Why?

Back 73

People who drink lots of alcohol

Alcohol is metabolised in the liver where it is oxidised to ethanol (by dehydrogenation)

It is then oxidised again from ethanol to ethanoate (acetate)

When these substances are reduced, the hydrogen atoms are combined with NAD, which means there is less NAD available for respiration purposes.

Front 74

Which stages of respiration occur in the mitochondria?

Back 74

Link reaction

Krebs cycle

Oxidative phosphorylation

Front 75

How might some humans' mitochondrias be different from cell to cell?

Back 75

Trained athletes may have larger mitochondria in their muscle cells

Metabolically active cells (e.g. hepatocytes) may have many more mitochondria, which may be larger and have more densely packed cristae (larger surface area for electron transport change and ATP synthase enzymes)

Front 76

Why has it been suggested that mitochondria are derived from prokaryotes?

Back 76

-Similar in length

-Both have 70s ribosomes (smaller)

-Both have similar style of DNA

Front 77

Why does glycolysis support the theory of evolution?

Back 77

It is found and remains in all cell types of all species.

Front 78

Describe the phosphorylation stage of glycolysis

Back 78

In glyclosis , which is the first stage, an ATP molecule is hydrolysed to ADP and Pi. The Pi is released and attaches to a glucose molecule at carbon 6. This changes the glucose to glucose 6 phosphate. This isomerises to fructose 6 phosphate. Another ATP molecule is hydrolysed, and this Pi is released and attaches to fructose 6 phosphate. This changes the sugar to fructose 1,6,bisphosohate. This sugar is too large to leave the cell. so broken down into 2 Triose phosphate then into 2 pyruvate.

Front 79

How many ATP are used and made in glycolysis?

Back 79

4 ATP molecules made

2reduced NAD molecules made

net increase of 2 ATP

Front 80

Name 4 photosynthetic pigments

Back 80

-chlorophyll a or b

-carotene

- xanthophyl

Front 81

Explain why plants with several photosynthetic pigments can make more starch than plants with just one photosynthetic pigments

Back 81

Explain why plants with several photosynthetic pigments can make more starch than plants with just one photosynthetic pigments

Front 82

Wat is limiting factor ?

Back 82

Is the factor that is the least favourable , which limits the rate of photosynthesis . If that factor is increased then the rate of photosynthesis increases

Front 83

Explain fully how each of the following factors can limit the rate of photosynthesis ? 1)Low temp

Back 83

Low temperature-reduced kinetic enery of enzymes and substrates involved in LIS

- fewer successful collisions between enzymes and substrates-rubisco, RuBP and C02

-less starch made

Front 84

Explain fully how each of the following factors can limit the rate of photosynthesis ? b) low intensity

Back 84

Fewer photon absorbed by photosynthetic pigmentsFewer excited electronsLess ATP and NADPH producedLess conversation of GP to TPLess starch

Front 85

Suggest why on a hot day the rate of photosynthesis may be less at noon

Back 85

-Increased temp

-Increase rate of transpiration

-Reduced water availability

-Stomata close so less uptake of C02

Or-Increase temp

-at higher temp ,enzyme become denatured

-Enzyme needed in light independent stage (rubisco)

-Rate of photosynthesis decreases

Front 86

function of adrenal glands

Back 86

The Adrenal Glands are located above the kidneys.

There are 2 regions within the glands.

Medulla region - Adrenaline is synthesised from amino acids and is secreted by the medulla, in response to danger, excitement or stress. This is also part of the fight/flight response.

Cortex region - Produces cholesterol to produce steroid hormones such as mineralocorticoids (e.g. aldosterone) which help control the concentration of sodium and potassium ions in the blood. The glucocorticoids control synthesis of glycogen, carbohydrates and proteins in the live.

Front 87

Outline the hormonal and nervous mechanism involved in control of the heart

Back 87

> adrenaline increases heart rate

>cardiovascular center in medula oblangata

>parasympathetic decreases heart rate

>sympathetic increases heart rate

>high blood pressure detected by stretch receptor

>low ph caused by increase co2 detected by chemoreceptor

>nervous system connected to SAN

>receptor in aorta/carotid