Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology A-Level > Stimuli and Responses > Flashcards

Stimuli and Responses Flashcards

(60 cards)

Start Studying
1
Q

Define stimulus

A

Any change in the internal or external env

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why do animals and plants respond to changes in their env?

A
  • External : to inc chances of survival eg. avoid harmful env
  • Internal: to make sure conditions are optimum for metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define receptors

A
  • Detect specific stimuli
  • Can be cells/proteins on cell surface membranes
  • Loads of diff. types
  • Communicate w/ effector
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define effector

A
  • Cells that bring about a response to a stimulus, produce effect
  • Eg. Muscles + glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define nervous system

A

Complex network of cells called neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Sensory neurones

A

Transmit electrical impulses from receptor to CNS (brain + spinal cord)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Motor neurones

A

Transmit electrical impulses from CNS to effectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Relay neurones

A

Transmit electrical impulses btw sensory neurones + motor neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Outline what happens when a stimulus is detected

A
  • Stimulus detected by receptor cells
  • Electrical impulse sent along sensory
  • At synapse, NT is sent
  • CNS processes info + sends impulse along motor
  • Impulse sent to effector
  • Response occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

CNS

A

Made up of brain + spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Peripheral NS

A
  • Made up of neurones that connect CNS to rest of body
  • Has 2 systems: somatic NS + autonomic NS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Somatic NS

A

Controls conscious activities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Autonomic NS

A
  • Controls unconscious activities
  • 2 divisions: sympathetic NS + parasympathetic NS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Parasympathetic NS

A

Gets body ready for action - fight or flight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sympathetic NS

A

Calms body down - rest and digest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define reflex

A
  • Body responds to stimulus w/o conscious decision to respond
  • Protect body bc rapid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the reflex arc?

A
  • Stimulus
  • Receptor
  • Sensory
  • Relay
  • Motor
  • Effector
  • Response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the nervous system communication

A
  • Localised: NT secreted directly to target cells
  • Short-lived: NT removed quickly
  • Rapid : electrical impulses are really fast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give examples to how plants respond to changes in their env to inc their chances of survival

A
  • Sense direction of light + grow towards it to max light absorption for photosynthesis
  • Sense gravity, roots + shoots grow in right direction
  • Climbing plants: sense of touch, find things to climb + reach sunlight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define tropism

A

Plant’s growth response to directional stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do plants respond to stimuli?

A

By regulating their growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Positive tropism

A

Growth towards stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Negative tropism

A

Growth away from stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Phototropism

A
  • Growth of plant in response to light
  • Shoots: +ve phototropism - grow towards light
  • Roots: -ve phototropism - grow away from light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Gravitropism
* Growth of plant in response to **gravity** * **Shoots**: **-ve** gravitropism - grow **upwards** * **Roots**: **+ve** gravitropism - grow **downwards**
26
Growth factors
* **Hormone like-chemicals** that **speed up/slowdown** plant **growth** eg. **Indoleacetic acid** (IAA) * Produced in **growing regions (tips)** * **Shoots**: **stimulate** growth by **cell elongation** - cell walls become **loose** + stre**t**chy * **Roots**: **inhibit** growth
27
How does IAA move around a plant?
* **Diffusion** + **AT** (**short** distance) * **Phloem** (**long** distance)
28
How does IAA respond to phototropism in the shoots and roots?
* Moves to **shaded** area - **uneven distrubution** = **uneven growth**​ * **Shoots**: cells **elongate** + **bend towards** light * **Roots**: **inhibits** growth so **bends away** from light
29
How does IAA respond to gravitropism in the shoots and roots?
* IAA moves **underside** - **uneven distrubution** = **uneven growth** * **Shoots**: cells **elongate** + grow **upwards** * **Roots**: growth **inhibited** so grow **downwards**
30
How do mobile organisms respond to keep in favourable env?
* **Tactic** response (**taxes**) * **Kinetic** response (**kineses**)
31
Tactic response (taxes)
Organism move towards or away from **directional stimulus** eg. **light**
32
Kinetic response (kineses)
Organisms' movement is affected by **non-directional stimulus** eg. **humidity**
33
Give one similarity and one difference between a taxis and a tropism (2)
* Similarity: **directional response** to stimulus * Difference: - **Taxi organism moves** AND **tropism growth** response - Taxi occurs w/ **animals** AND tropism occurs in **plants**
34
Outline what a choice chamber is
Container w/ diff compartments in which you can create **diff environmental conditions**
35
Outline how you can use a choice chamber to investigate animal response to diff conditions
* **Light intensity:** **cover half** of **lid** w/ **black pape**r - one side of chamber will be dark. Put damp filter paper on both sides * Place **woodlice** on **mesh** + **cover** w/ lid * After 10mins record no. woodlice on each side - **most** will end up in **dark side** (**tactic** response to light) * **Humidity**: **damp filter paper** in one side + **desiccating drying agent** in other side
36
What are pacinian corpuscles?
* **Mechanoreceptors** - detect **mechanical** **stimuli** eg. **pressure** + **vibrations** * Found in **skin** * Contain **sensory nerve ending** which is **wrapped** in **loads** of **layers** of **connective tissu**e called **lamellae**
37
What happens when a pacinian corpuscle is stimulated?
* **Lamellae** are **deformed** + **press** on **sensory nerve ending** * Causes **sensory neurone**' **cell membrane** to **stretch**, **deforming stretch mediated sodium ion channels** * **Channels open** + **sodium ions diffuse** into cell, causing **generator potential** * If GP reaches **threshold**, **triggers action potential**
38
How does light enter the eyes?
Through **pupil**
39
The amount of light that enter the eyes is controlled by what?
Muscles of the **iris**
40
What is the role of the retina?
* **Fovea**, area in retina, contains **photoreceptor cells** - **detect light** * **Nerve impulses** are carried from **retina** to **brain** by **optic nerve** - **bundle** of **neurones**
41
What is the role of the lens?
**Focuses** light rays onto **retina**
42
What is the blind spot?
* Where **optic nerve leaves** * **No photoreceptor** cells so **not sensitive** to **light**
43
What happens when light enter the eye?
* Hits **photoreceptors** + **absorbed** by **light sensitive optical pigments** * Light **bleaches pigments**, causing **chemical change**, **altering membrane permeability** to **sodium ions** * **Generator potential** created if **threshold reached**, **nerve impulse sent** along **bipolar neurone** * BP **connects photoreceptors** to **optic nerve**, takes impulse to **brain**
44
What are the types of photoreceptors?
* Rods * Cones
45
What are the differences btw rods and cones?
* **R**: found in **periphera**l part of **retina**, **C**: **packed together** in **fovea** * **Different optical pigments** so **sensitive** to **diff** **wavelengths** of light * R: **black + white**, C: **colour** (3 types of cones: **red**, **green**, + **blue**)
46
Which photoreceptor is more sensitive to light?
* **Rods** (work well in **dim light**) : **many rods join 1 neurone**, **many weak GP combine** to **reach threshold** + trigger AP * **Cones less sensitive** : **1 cone joins 1 neurone** so takes **more light** to reach threshold
47
Which photoreceptor has a higher visual acuity?
* **Cones** : **close togethe**r + **1 cone join 1 neuron**e so when **light** hits **2 cones**, **2 AP** go to brain so can **distinguish** 2 points as **seperate points** * **Rods** : **many rods join same neurone**, **light** from **2 close points can't** be told apart
48
The heart is myogenic. What does this term mean?
Can **contract** + **relax** **w/o recieving signals** from **nerves**
49
The heart rate controls + coordinates the regular contraction of the atria + ventricles. Describe how (5)
* Sinoatrial node (**SAN**) acts as **pacemaker** * Sends **wave** of **electrical activity** to **atria** causing **atrial contraction** at same time * **Non-conducting tissue** * Transferred to atrioventricular node (**AVN**) * **Delay** at **AVN** ensure **atria empty** before **ventricle contract** * AVN sends electrical impulse to **bundle of His/purkyne tissue** * Causing **ventricle** to **contract** from base up
50
What is the function of the non-conducting collagen tissue?
**Prevents** waves of **electrical activity** from being **passed directly** from **atria** to **ventricle**. Instead **transferred** to **AVN**
51
Explain the importance of the slight delay at the AVN (2)
* Allow **ventricles** to **fill**/**atria** to **empty** * Before **ventricles contract**
52
Outline the function of the bundle of His
* **Group** of **muscle fibre** * **Conducts electrical activity** btw **ventricles** to **apex** of heart
53
Outline the function of the purkyne tissue
* **Bundle** of His **splits** into **finer muscle fibres** in **right** + **left ventricle wall** * Carries **electrical activity** into **muscular wall** of **right** + **left ventricle**, causing them to **contract** at **same time** from **bottom up**
54
What is the role of the medulla oblongata?
**Unconsiously controls rate** at which **SAN generates electrical impulses** causing **cardiac muscle** to **contract**
55
Baroreceptors
* **Pressure receptors** * In **aorta** + **carotid arteries** * **Stimulated** by **high** + **low BP**
56
Chemoreceptors
* **Chemical receptors** * In **aorta**, **carotid arteries** + **medulla** * **Moniter O**2 , **CO**2 + **pH** level in **blood**
57
How does the heart respond to a high blood pressure?
* **Baroreceptors** detect **high BP** * Electrical **impulses** sent to **medulla**, sends impulses along **parasympathetic neurones**. **Secretes acetylcholine**, **binds** receptors on **SAN** * Effector: **cardiac muscles** * **HR slows** to **reduce BP**
58
How does the heart respond to a low blood pressure?
* **Baroreceptors** detect **low BP** * Electrical **impulses** sent to **medulla**, sends impulses along **sympathetic neurones**. **Secretes noradrenaline**, **binds** to receptors on **SAN** * Effector: **cardiac muscles** * **HR speeds up** to **inc BP**
59
How does the heart respond to high blood O2 , low CO2 or high pH level?
* **Chemoreceptor**s detect **chem change** * **Impulse** sent along **medulla**, sends impulses along **parasympathetic neurones**. **Secrete acetylcholine**, **binds** to receptors on **SAN** * Effector : **cardiac muscle** * **HR dec**
60
How does the heart respond to low blood O2 , high CO2 or low pH level?
* **Chemoreceptors** detect **chem change** * **Impulse** sent along **medulla**, sends impulses along **sympathetic neurones**. **Secrete noradrenaline**, **binds** to receptors on **SAN** * Effector : cardiac muscle * HR inc

Biology A-Level (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions