Organisms Respond to their Environment (3.6) Flashcards
1
Q
Survival & Response (AO1)
Organisms [1] their chance of survival by responding to [2] in their environment.
A
[1] increase
[2] changes
2
Q
Survival & Response (AO1)
List two simple responses by small organisms such as insects
A
Taxis
Kinesis
3
Q
Survival & Response (AO1)
Function of taxis and kinesis for mobile organisms?
A
1. Keep organisms in a favourable environment.
(e.g. more food, more mates, less predators, less desiccation)
2. Increase chances of survival
4
Q
Survival & Response (AO1)
Define taxis
A
Directional movement in response to a stimulus
5
Q
Survival & Response (AO1)
Positive taxis
A
Directional response with movement towards the stimulus
6
Q
Survival & Response (AO1)
Negative taxis
A
Directional response with movement away from the stimulus
7
Q
Survival & Response (AO1)
Define kinesis
A
Random OR non-directional movements in response to the stimulus
8
Q
Survival & Response (AO2)
A
Behaviour:
(Positive photo) taxis;
Advantage:
Avoid competition / to find a mate / increase dispersal / to avoid predators;
9
Q
Survival & Response (AO2)
A
1. Kinesis;
2. Movement is random / non-directional
10
Q
Survival & Response (AO2)
A
Taxis
11
Q
Survival & Response (AO1)
Give one similarity and one difference between a taxis and a tropism.
A
Similarity − directional response to a stimulus / movement towards OR away from a stimulus;
Difference − in taxis whole organism moves whereas tropism a growth response in part of the plant (e.g. shoot or root tips).
OR
Difference - taxis occurs in animals whereas tropisms occurs in plants
12
Q
Survival & Response (Maths)
A
11.1%
13
Q
Survival & Response (AO2)
A
Taxis
B moves towards stimulus / light
14
Q
Survival & Response (AO2)
A
kinesis;
random / non-directional movements;
15
Q
Survival & Response (AO1)
In flowering plants, specific [1] factors move from growing regions to other tissues, where they regulate growth in response to directional [2].
A
[1] growth
[2] stimuli
16
Q
Survival & Response (AO1)
Which organisms demonstrate tropisms?
A
Plants
17
Q
Survival & Response (AO1)
Define tropism
A
Response of a plant to a directional stimulus
18
Q
Survival & Response (AO1)
Stimuli that cause tropisms
A
Light
Gravity
Water
Salinity
19
Q
Survival & Response (AO1)
Positive phototropism
A
Directional response of shoot tips towards light
20
Q
Survival & Response (AO1)
Directional response of root tips away from light
A
negative phototropism
21
Q
Survival & Response (AO1)
Positive gravitotropism
A
Directional response of root tips towards gravity
22
Q
Survival & Response (AO1)
Auxis are a family of growth factors that cause tropisms. Which specific auxin must you know.
A
IAA
Full name: Indoleacetic acid
23
Q
Survival & Response (AO1)
Where is IAA synthesised?
A
Shoot tips &
root tips
24
Q
Survival & Response (AO1)
How does IAA move into the growing region of the shoot or root tip?
A
Diffusion
25
# **Survival & Response (AO1)**
Where does IAA build up in the shoot tips in response to light?
On the shaded side
26
# **Survival & Response (AO1)**
Effect of IAA in the shoot tips
1. **Stimulates elongagation of cells** on the shaded side;
2. Causes shoot to bend towards the light;
*(this is a positive phototropism)*
27
# **Survival & Response (AO1)**
Where does IAA build up in the root tips in response to gravity?
On the side closest to gravity / on the underside
28
# **Survival & Response (AO1)**
Effect of IAA in the root tips
1. **Inhibits elongagation of cells** on the underside;
2. Cells on opposite side (away from gravitiy) can elongate and cause the root tip to bend towards gravity;
29
# **Survival & Response (AO2)**
**1.** Tip produces/synthesises IAA;
**2.** IAA diffuses (into growing region of shoot);
**3.** Stimulates elongation of cells on one side (than other);
30
# **Survival & Response (AO2)**
**1.** Tip produces IAA;
**2.** Affects concentration of IAA
OR Affects (shoot) length/growth/elongation;
31
# **Survival & Response (Maths)**
0.4cm^3 stock IAA + 39.6cm^3 water
*Step by step working:*
**C1 x V1 = C2 x V2**
C1 = stock concentration
V1 = volume of stock
C2 = desired concentration
V2 = desired volume
1 x V1 = 0.01 x 40
V1 = 0.4cm^3 of IAA stock + 39.6cm^3 of water
32
# **Survival & Response (AO2)**
**1.** Grow in direction of / towards (pull of) gravity;
Accept: tropism for growth
Accept: positively geotropic / gravitropic
**2.** Grow away from salt;
**3.** Salt has more effect than gravity;
33
# **Survival & Response (AO2)**
**1.** Seedlings / root tips respond to light;
**2.** Only measuring the effect of gravity;
34
# **Survival & Response (AO2)**
When a young shoot is illuminated from one side, IAA stimulates growth on the shaded side.
Explain why growth on the shaded side helps to maintain the leaves in a favourable environment (*2 marks*).
**1.** Causes plant to bend / grow towards light / positive phototropism;
**2.** Light energy required for photosynthesis;
35
# **Survival & Response (AO1)**
**TRUE or FALSE:**
IAA is only produced in the light
FALSE
| IAA is produced in the light AND dark
36
# **Survival & Response (AO1)**
Draw out a simple reflex arc
(include the neurons and an effector)
37
# **Survival & Response (AO1)**
Which neuron in the simple reflex arc contains receptors to the stimulus?
Sensory
38
# **Survival & Response (AO1)**
Suggest two advantages of simple reflexes
1. Rapid;
2. Protect against damage to body tissues;
3. Do not have to be learnt / innate behaviour / involuntary;
4. Help escape from predators;
5. Enable homeostatic control;
6. Finding suitable conditions / keep organism in favourable environment;
39
# **Survival & Response (AO1)**
Give two types of cell that act as effectors.
Muscles
Glands
(which produce hormones)
40
# **Survival & Response (AO1)**
Only 3 neurones
41
# **Survival & Response (AO1)**
What is found between the sensory neuron and relay neuron
Synapse
42
# **Nerve impulses (AO1)**
Draw out and annotate a myelinated motor neuron
43
# **Nerve impulses (AO1)**
What is found on the cell surface membrane of the dendrites?
Receptors
44
# **Nerve impulses (AO1)**
Organelles in the cell body of a neuron
Nucleus
Golgi apparatus / body
Ribosomes / Rough ER
Mitochondria
45
# **Nerve impulses (AO1)**
Specialised cell that produces the myelin sheath
Schwann cell
46
# **Nerve impulses (AO1)**
Biological molecule found in myelin sheath
phospholipids
| Myelin also contains cholesterol, so similar to cell surface membrane.
47
# **Nerve impulses (AO1)**
Released by axon terminals
neurotransmitters
| e.g. acetylcholine, dopamine, serotonin
48
# **Nerve impulses (AO1)**
Process at nodes of ranvier
saltatory conduction
49
# **Nerve impulses (AO1)**
Stages of an action potential
- Resting potential,
- (Threshold potential),
- Depolarisation,
- Repolarisation,
- Hyperpolarisation,
- Re-establish resting potential.
50
# **Nerve impulses (AO1)**
Resting potential in mV
-70mV
| This means inside of axon is LESS positive than outside
51
# **Nerve impulses (AO1)**
Channel proteins found in axon cell surface membrane
**Voltage-gated** sodium **ion** channels
**Voltage-gated** potassium **ion** channels
52
# **Nerve impulses (AO1)**
Explain how a resting potential is maintained across the axon membrane in a neurone (*3 marks*).
**1.** Sodium **ions** actively transported **OUT** and potassium **ions** IN;
**2.** **LESS permeable to sodium ions as voltage-gated channels closed***OR membrane MORE permeable to potassium ions as some voltage-gated channels open*;
**3.** Higher concentration of potassium ions inside **AND** higher concentration of sodium ions outside the axon
53
# **Nerve impulses (AO1)**
The sodium potassium ion pump establishes an ________________ gradient.
electrochemical gradient
| i.e., higher sodium ion concentration outside the axon, lower inside.
54
# **Nerve impulses (AO1)**
Threshold potential in mV
-55mV
55
# **Nerve impulses (AO1)**
Channel open at -55mV
**Voltaged-gated** sodium **ion** channels
56
# **Nerve impulses (AO1)**
The all-or-nothing principle
An action potential is only generated/produced when threshold stimulus is reached (-55mv)
OR
An action potential is not generated/produced until/unless threshold stimules is reached (-55mv);
| If stimulus reached, voltage-gated sodium ion channels open
57
# **Nerve impulses (AO1)**
Sodium and potassium ions can only cross the axon membrane through channel proteins. Explain why (*2 marks*).
**1.** Cannot pass through phospholipid bilayer
(via simple diffusion)
**2.** because they are NOT lipid soluble
OR because they are charged;
58
# **Nerve impulses (AO2)**
A scientist investigated the effect of inhibitors on neurones. She added a respiratory inhibitor to a neurone. The resting potential of the neurone changed from –70 mV to 0 mV.
Explain why (**3 marks**).
**1.** No/less ATP produced;
**2.** No/less active transport
OR fewer sodium ions moved out.
OR Sodium/potassium pump inhibited;
**3.** Electrochemical gradient not maintained
OR same concentration of sodium and potassium ions either side of axon membrane
59
# **Nerve impulses (AO1)**
**C**
60
# **Nerve impulses (AO1)**
Sodium ions diffusing into the axon via open voltage-gated channels leads to___________________.
depolarisation
61
# **Nerve impulses (AO1)**
Why does the graph increase from -55mV to +40mV?
**1.** **Voltage-gated** sodium **ion** channels are open
**2.** Sodium ions **diffuse** into the axon via faciliated diffusion (DOWN an electrochemical gradient)
**3.** Inside of the axon **MORE positive**
62
# **Nerve impulses (AO1)**
What happens at +40mV?
Voltage-gated sodium ion channels **CLOSE**
**AND**
Voltage-gated potassium ion channels **OPEN**
63
# **Nerve impulses (AO1)**
Why does the graph decrease after +40mV during repolarisation?
**1.** **Voltage-gated potassium ion channels are open** (& voltage-gated sodium ion channels are closed).
**2.** Potassium ions **rapidly diffuse OUT** of the axon via faciliated diffusion (DOWN an electrochemical gradient)
**3.** Inside of the axon **LESS positive**
64
# **Nerve impulses (AO1)**
Hyperpolarisation in mV
-90mV
65
# **Nerve impulses (AO1)**
What causes hyperpolarisation?
**1.** Voltage-gated potassium ion channels stay open;
**2.** Potassium ions diffuse out of axon;
**3.** Inside of axon becomes even LESS positive (decreasing from -70mV to -90mV).
66
# **Nerve impulses (AO1)**
Channels closed at -90mV
**Voltage-gated** potassium **ion** channels (close at -90mV)
**Voltage-gated** sodium **ion** channels (already closed during repolarisation)
67
# **Nerve impulses (AO1)**
Explain how the resting potential is re-established (*2 marks*).
**1.** Sodium potassium pump **uses energy from ATP hydrolysis**;
**2.** Sodium **ions** actively transported OUT and potassium **ions** IN.
*Both ions move AGAINST their concentraton gradient from low to high.*
68
# **Nerve impulses (AO1)**
Explain why the speed of transmission of impulses is faster along a myelinated axon than along a non-myelinated axon (*3 marks*).
**1.** Myelination provides insulation;
**2.** In myelinated axon saltatory conduction occurs
OR In myelinated axon depolarisation only occurs at nodes of Ranvier;
**3.** In non-myelinated axon, depolarisation occurs along whole length of axon;
69
# **Nerve impulses (AO1)**
Refractory period
**1.** Time during which a new action potential **cannot** be generated;
**2.** It lasts from the threshold potential until the resting potential has been re-established;
70
# **Nerve impulses (AO1)**
Importance of the refractory period
**1.** Action potentials occur in one direction
**2.** Each impulse / action potential is discrete
**3.** Number of action potential is limited
71
# **Nerve impulses (AO1)**
Factors affecting speed of impulse conductance along an axon
Myelination
Temperature
Axon diameter
72
# **Nerve impulses (AO1)**
Explain how myelination affects conductance of an impulse
Insulates axon;
Depolarisation only occurs at nodes of Ranvier;
Leads to salatory conduction *(action potential 'jumps' between nodes of Ranvier)*;
Impulse / action potential moves **FASTER** along axon;
73
# **Nerve impulses (AO1)**
Explain how increasing temperature affects conductance of an impulse
More kinetic energy;
Faster rate of diffusion of sodium and potassium ions DOWN electronchemical gradient;
Faster rate of diffusion of sodium ions within axon;
Impulse / action potential moves **FASTER** along axon;
74
# **Nerve impulses (AO1)**
Explain how increasing axon diameter affects conductance of an impulse
**1.** Larger surface area so more cell-surface membrane for voltage-gated sodium/potassium ion channel proteins;
**2.** Less resistance to flow ions within the axon;
75
# **Nerve impulses (AO2)**
Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding neurones are destroyed.
Explain how this results in slower responses to stimuli (*2 marks*).
**1.** Less / no saltatory conduction / action potential / impulse unable to ‘jump’ from node to node;
**2.** More depolarisation over length of membranes;
76
# **Nerve impulses (AO1)**
D
B
C
77
# **Receptors (AO1)**
Receptor to detect change in pressure
Pacinian corpuscle
78
# **Receptors (AO1)**
**P =** capsule/lamella(e)
**Q =** Axon (membrane) / (sensory) neurone
**R =** Schwann cell(s) / Myelin sheath
79
# **Receptors (AO1)**
Channel proteins in Pacinian corpuscle
**Stretch-mediated** sodium **ion** channel proteins
80
# **Receptors (AO1)**
Describe how stimulation of a Pacinian corpuscle produces a generator potential (*3 marks*).
**1.** Increased pressure deforms membrane/lamella(e)
**2.** This opens the stretch-mediated sodium ion channels (in the membrane);
OR (Increased pressure) deforms/changes sodium ion channels;
**3.** Sodium ion channels open;
**4.** Sodium ions diffuse in;
**5.** Depolarisation (leading to generator potential);
81
# **Receptors (AO1)**
**TRUE or FALSE:**
The generator potential must exceed the threshold stimulus to trigger an action potential in the sensory neuron
TRUE
82
# **Receptors (AO1)**
[1] pressure leads to more stretch-mediated sodium [2] channels opening. This leads to [3] and makes it more likely the generator potential produced exceeds the [4] stimulus for an action potential.
This is an example of the [5] principle.
[1] Increased
[2] ion
[3] depolarisation
[4] threshold
[5] all or nothing
83
# **Receptors (AO1)**
**TRUE or FALSE:**
A new generator potential in the axon of the Pacinian corpuscle can be produced during the refractory period.
FALSE
| The resting potential inside the axon must be re-established
84
# **Receptors (AO1)**
Example of photoreceptors
Rods & cones
85
# **Receptors (AO1)**
Photoreceptors location
Macula
(middle of retina)
86
# **Receptors (AO1)**
Cone location
Fovea
(the centre of the macula)
87
# **Receptors (AO1)**
Rod location
Edges of the macula
(not present in the fovea)
88
# **Receptors (AO1)**
Rods and cones convert [1] energy into electrical energy in the form of [2].
[1] light
[2] action potentials / nerve impulses
89
# **Receptors (AO1)**
Sensivity of rods
High sensivity to low light intensity
90
# **Receptors (AO1)**
In rods, light breaks down the pigment [1] and this leads to the release of [2]. This leads to a [3] potential in the [4] neurone.
[1] rhodopsin
[2] neurotransmitter
[3] generator
[4] bipolar
91
# **Receptors (AO1)**
Retinal convergence
**Several rod cells** connected to a **single bipolar neurone**
92
# **Receptors (AO1)**
Spatial summation
Release of neurotransmitter from one rod cell leads to generator potential **below threshold stimulus** in the bipolar neurone
Neurotransmitter released from several/additional rods cells connected to same bipolar neurone helps **exceed the threhold** and trigger an action potential
93
# **Receptors (AO1)**
Photoreceptor with low visual acuity
Rods
94
# **Receptors (AO1)**
Acuity
How clear / detailed the image is
95
# **Receptors (AO1)**
Photoreceptor with high visual acuity
cones
96
# **Receptors (AO1)**
Types of cone cells
3 cone cells specific to different wavelengths of light: red, blue & green.
97
# **Receptors (AO1)**
Sensivity of cones
Low sensitivity to low light intensity
98
# **Receptors (AO1)**
In cones, high intensity light breaks down the pigment [1] and this leads to the release of [2]. This leads to a [3] potential in the [4] neurone.
[1] iodopsin
[2] neurotransmitter
[3] generator
[4] bipolar
99
# **Receptors (AO1)**
Each [1] cell is connected to a single [2] neurone. This sends [3] impulses to the visual cortex via the optic nerve.
[1] cone
[2] bipolar
[3] separate
100
# **Receptors (AO2)**
The fovea of the eye of an eagle has a high density of cones. An eagle focuses the image of its prey onto the fovea.
Explain how the fovea enables an eagle to see its prey in detail.
Do **not** refer to colour vision in your answer (*3 marks*).
**1.** Each cone cell is connected to a single bipolar neurone
OR no retinal convergence;
**2.** Cones send **separate** (sets of) impulses to brain / optic nerve;
**3.** Produces high visual acuity;
101
# **Receptors (AO2)**
The retina of an owl has a high density of rod cells.
Explain how this enables an owl to hunt its prey at night.
Do **not** refer to rhodopsin in your answer (*3 marks*).
**1.** High sensitivity to low light intensity
**2.** Retinal converage OR several rods connected to a single bipolar neurone;
**3.** Enough neurotransmitter released to reach/overcome threshold
OR spatial summation to reach/overcome threshold;
102
# **Receptors (AO2)**
no photoreceptor cells at Y
OR no rods and cones;
103
# **Control of heart rate (AO1)**
Cardiac muscle is ____________
myogenic
104
# **Control of heart rate (AO1)**
Define myogenic
Contraction is initiated from within the muscle itself;
due to the action of the sinoatrial node (**SAN**)
(which acts as a 'pacemaker')
105
# **Control of heart rate (AO1)**
Nodes required for initiation and coordination of a heartbeat / cardiac cycle.
Sinoatrial node (**SAN**)
Atrioventricular node (**AVN**)
| *Note:* you only need to recall **'SAN'** and **'AVN'**
106
# **Control of heart rate (AO1)**
**SAN** location
Upper wall of **right** atrium
107
# **Control of heart rate (AO1)**
**AVN** location
Base of **right** atrium
108
# **Control of heart rate (AO1)**
**bundle of his** location
(ventricular) septum
## Footnote
The septum separates the L & R atria and ventricles
109
# **Control of heart rate (AO1)**
The sinoatrial node (SAN) is in the right atrium of the heart. Describe the role of the sinoatrial node (*2 marks*).
Sends out waves of electrical activity / impulses;
Which stimulates the contraction of atria OR acts as a 'pacemaker';
110
# **Control of heart rate (AO1)**
Describe how a heartbeat is initiated and coordinated (*5 marks*).
**1.** SAN sends wave of electrical activity / impulses across atria causing atrial contraction;
**2.** Non-conducting tissue prevents impluse spreading to the ventricles
**3.** AVN delays impulse whilst blood leaves atria and the ventricles fill;
**4.** AVN sends wave of electrical activity / impulses down the Purkinje fibres / bundle of His;
**5.** Causing ventricles to contract from base up;
111
# **Control of heart rate (AO1)**
When the heart beats, both ventricles contract at the same time.
Explain how this is coordinated in the heart after initiation of the heartbeat by the SAN (*2 marks*).
**1** Electrical activity only through AVN / purkinje fibres / bundle of His;
**2.** Wave of electrical activity passes over / through both ventricles at the same time;
112
# **Control of heart rate (Maths)**
Cardiac output equation
Cardiac output (CO) = stroke volume (SV) x heart rate (HR)
| **NOTE:** Cardiac output is on spec for both paper 1 **AND** paper 2
113
# **Control of heart rate (Maths)**
**TRUE or FALSE:**
Heart rate is the length of one cardiac cycle in seconds
FALSE
| Heart rate is the number of cardiac cycles / heart beats **per minute**
114
# **Control of heart rate (Maths)**
One cardiac cycle is 0.85s, what is the heart rate?
60 / 0.85 = 70.588 or 71 bpm
115
# **Control of heart rate (Maths)**
Heart rate of 62 bpm and a cardiac output of 4785cm^3 min^-1 - what is the stroke volume?
77 cm^3
116
# **Control of heart rate (Maths)**
Convert 620 milliseconds (ms) into seconds (s)
620 / 1000 = 0.62s
117
# **Mass Transport in Animals (Maths)**
Convert 4.27 seconds (s) into milliseconds (ms)
4.27 x 1000 = 4270ms
118
# **Control of heart rate (Maths)**
8 beats in 800 ms
1 beat = 100 ms / 0.1s
Heart rate = 60 / 0.1 = 600bpm
CO = SV x HR
CO = 0.03 x 600 = 18cm^3 min^-1
119
# **Control of heart rate (Maths)**
Use the below graph to determine the length of one cardiac cycle.
Peak to peak OR trough to trough
e.g.1.24 - 0.48 = 0.76s
120
# **Control of heart rate (Maths)**
Use the below graph to determine stroke volume.
120 - 40 = 80cm^3
121
# **Control of heart rate (Maths)**
60 / 0.9 =
66.7 or 67 bpm
| One cardiac cycle or heart beat = 0.9 seconds
122
# **Control of heart rate (AO1)**
Branches of the autonomic nervous system
sympathetic
parasympathetic
123
# **Control of heart rate (AO1)**
Increased activity of the ____________ nervous system **increases** heart rate
sympathetic
124
# **Control of heart rate (AO1)**
Increased activity of the ____________ nervous system **decreases** heart rate
parasympathetic
125
# **Control of heart rate (AO1)**
Receptors for blood pressure
baroreceptors
126
# **Control of heart rate (AO1)**
Baroreceptor location
aorta
carotid artey*
| *supply blood to brain
127
# **Control of heart rate (AO1)**
Cardiac centres location
Medulla oblongata
128
# **Control of heart rate (AO1)**
Neurotransmitter released by parasympathetic nervous system
acetylcholine
129
# **Control of heart rate (AO1)**
Explain how a rise in blood pressure results in a decrease in heart rate (*6 marks*).
**1.** Baroreceptors in the aorta / carotid arteries
**2.** Send impulses to cardiac centres / medulla oblongata;
**3.** Increased frequency of impulses sent via parasympathetic nerves;
**4.** to SAN;
**5.** Release of acetylcholine inhibits SAN so decreases impulses;
**6.** So decreased implules to AVN;
130
# **Control of heart rate (AO1)**
Neurotransmitter released by sympathetic nervous system
noradrenaline
131
# **Control of heart rate (AO2)**
Suggest how caffeine increases heart rate (*2 marks*)
**1.** More impulses/action potentials along sympathetic nervous system;
**2.** To SAN
132
# **Control of heart rate (AO1)**
Receptors for carbon dioxide concentration in blood
chemoreceptors
133
# **Control of heart rate (AO1)**
Chemoreceptor location
aorta
carotid artey*
| *supply blood to brain
134
# **Control of heart rate (AO1)**
Exercise causes an increase in heart rate.
Describe the role of receptors and of the nervous system in this process (*4 marks*).
**1.** Chemoreceptors detect rise in carbon dioxide in blood
**2.** Send impulses to cardiac centres / medulla oblongata;
**3.** More / increases frequency of impulses to SAN;
**4.** via sympathetic nervous system;
135
# **Control of heart rate (AO2)**
Some drugs inhibit the transmission of nerve impulses to the heart. Explain how these drugs reduce blood pressure (*2 marks*).
**1.** Inhibit impulses along sympathetic nervous system;
**2.** SAN not stimulated so less waves of electrical activity / impulses spread across atria;
