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_A2_ 1 - Flashcards

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1
Q

Negative Feedback

A

a process in which any change in a parameter brings about the reversal of that change so the parameter is kept fairly constant.

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2
Q

Positive Feedback

A

a process in which any change in a parameter brings about an increase in that change.

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3
Q

Homeostasis

A

the maintenance of a constant internal environment despite external changes.

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4
Q

Why is there a need for communication systems within multicellular organisms

A

in order to respond to changes in the internal and external environment and to coordinate the activities of different organs

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5
Q

Endocrine Gland

A

a gland that secretes hormones directly into blood capillaries.

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6
Q

Exocrine gland

A

a gland that secretes substances into a duct.

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7
Q

Target tissues/target cells ( check with teacher)

A

Cells that have receptors embedded in the plasma membrane that are complementary in shape to specific hormone molecules

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8
Q

First messenger

A

a hormone that acts as a message in the blood stream.

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9
Q

second messanger

A

a chemical inside the cell released in response to a hormone binding to the cell surface membrane eg. cAMP

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10
Q

Explain the principles of homeostasis in terms of receptors, effectors and negative feedback

A

stimulus—receptor—–communication pathway (cell signalling)—effector—-response

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11
Q

ectotherm

A

an organism that relies on external sources of heat to regulate its body temperature.

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12
Q

endotherms

A

an organism that can use internal sources of heat to maintain their body temperature.

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13
Q

generator potential

A

a small depolarisation caused by sodium ions entering the cell.

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14
Q

hormone

A

a molecule released into the blood that acts as a chemical messenger.

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15
Q

action potential

A

is achieved when the membrane is depolarised to a value of about +40 mV.

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16
Q

polarised membrane

A

is one that has a potential difference across it. this is the resting potential.

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17
Q

Depolarisation

A

the loss of polarisation across the membrane.

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18
Q

Receptor that detects (Light)

energy changes detected

A

Light sensitive cells - Rods/ cones - In the retina

What it detects - Light intensity

  • Range of wavelengths (colour)
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19
Q

Receptor that detects (smell)

energy changes detected

A

Olfactory cells lining the inner surface in the nasal cavity

What it detects - presence of volatilecemicals

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20
Q

Receptor that detects (taste)

energy changes detected

A

taste buds in the tongue, hard palate, epiglottis and the first part of the esophagus

What it detects -presence of soluble chemicals

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21
Q

Receptor that detects (feeling touch)

energy changes detected

A

pressure receptors (Pacinian corpuscles) in the skin

What it detects -Pressure on skin

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22
Q

Receptor that detects (sound)

energy changes detected

A

sound receptors in the inner ear (cochlea)

What it detects -vibrations in air.

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23
Q

Receptor that detects (movement of muscles)

energy changes detected

A

muscle spindles (proprioceptors)

What it detects - lengh of muscle fibres.

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24
Q

resting potential

A

is the potential difference or voltage across the neurone cell membrane while the neurone is at rest

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25
voltage--gated channels
the gates further along the neurone are opened by changes in the potential difference(voltage) accross the membrane.
26
saltatory conduction
means jumping conduction refers to the way thatthe action potential appears to jump from one node of Ranvier to the next.
27
local currents
are the movements of ions along the neurone.
28
photosynthesis
transforms light energy into chemical potential energy
29
autotrophs
organisms that use light energy or chemical energy and inorganic molecules (CO2, H2O), to make complex organic, molecules.
30
heterotrophs
organisms that ingest and digest complex organic molecules releasing the chemical potential energy stored in them. =it digests them into simpler, soluble molecules and then respires some of them to obtain enery, or uses the products of digestion to synthesise the organic molecules it needs. =are consumers in the foodchain eg.of heterptroph are parasites,saprotrophs
31
transduction
coverts/changing light energy into chemical energy.
32
photosynthetic pigments
- molecules that absorbs light energy - each pigment absorbs a range of wavelengths and each has its distinct peak of absorption. - located in photosystems in the thylakoid membranes ex. chlorophyll a, chlorophyll b and carotinoids
33
why is the synapse important in the working of the nervous system
=it keeps the electrical impulse moving in one direction =it allows for; Summation- adding a series for low frequency signals, to become a high frequency signal. Divergence-to send impulses to different parts of the body =it filters out low level signals >extra Q
34
Explain normal function low level signals
the threshold value has to be reached to trigger off the next action potential.
35
photosynthesis
is the process whereby light energy from the Sun is transformed into chemical energy and use to synthesize large organic molecules from inorganic substances.
36
autotroph
organism that makes its own food using simple inorganic molecules, such as carbon dioxide and water and energy.
37
photoautotrophs(plants, protoctist and some bacteria)
use light as the source of energy.
38
chemoautotroph (some bacteria)
use chemical energy
39
photosynthetic pigments
=are molecules that absorb light energy. =each pigment absorbs a range of wave lenghths and each has its distinct peak of absorption =located in photosystems in the thylakoid membranes.
40
nanometre (nm)
is one thousandth of a micrometre or one millionth of a millimetre
41
autotrophic Nutrition
involves the build up of simple inorganic molecules such as carbon dioxide and water into complex organic ones like glucose, proteins, starch,cellulose, lipids,sucrose.
42
heterotropic nutrition
involves the breakdown of complex organic molecules into simple soluble ones.
43
photoautotrophs
use light as their source of energy to drive photosynthesis.
44
chemoautotrophs
use energy from chemicals. the process is less common than photosynthesis, but takes place in certain bacteria such as the nitrifying and denitrifyning bacteria that are important in the nitrogen cycle.
45
outline photosynthesis word equation
carbon dioxide +water --> glucose + oxygen
46
outline photosynthesis symbol equatuion
CO2 +H2O-->C6H12O6 +O2
47
Photosynthesis is a process of energy transduction. Explain.
Converts/changing light energy into chemical energy.
48
chloroplasts
is where photosynthesis takes place in plants
49
primary pigments
are two forms of chlorophyll a with slightly different absorption peaks.
50
accessory pigments
transfers energy to the primary pigment
51
photosystem I (PSI)
has a chlorophyll a molecule that has a absorption peak of 700nm as its reaction centre, and is therefore known as P700
52
photosystem II (PSII)
has a chlorophyll a molecule that has an absorption peak at 680nm as its reaction centre, and is therefore known as P680
53
what colour are carotinoids
orange
54
The photosystems are found embedded in the membranes of the grana. Why is this an advantage?
it has a higher surface area for more photosynthesis to take place.
55
photophosphorylation
=adding phosphates to something using light, =means phosphorylation using light. =it refers to the production of ATP by combining a phosphate group (Pi) with ADP,using the energy that came from light.
56
chemiosmosis
the flow of hydrogen ions (protons) through ATP synthase enzymes = the force of this flow allows the production of ATP = occurs across the thylakoid membranes during the light-dependent stage of photosynthesis.
57
rubisco
the enzyme involved in the fixation of carbon dioxide
58
draw the calvin cycle
DRAW!!!
59
state where in the chloroplast the Calvin cycle occurs
in the stroma
60
ATP
another compound produced in the light dependent stage that is used in calvin cycle
61
CO2 is fixed what does this mean
inorganic CO2 is converted to organic GP(glycerate phosphate)
62
name the 8 factors necessary for photosynthesis | WCLH MLWC
water, carbon dioxide, light intensity,heat | minerals, leaves, wavelength of light, chlorophyll
63
what causes the rate of photosynthesis to suddenly stop increasing
insufficient CO2 concentrations or not enough temperature
64
what happen to the stomata at high temperatures
stomata closes
65
what effect will this have on the rate of photosynthesis
slows the rate down as CO2 is limited, less CO2 can diffuse into the leaves through closed stomata.
66
limiting factor
a factor that is in short supply or nearest its minimum value
67
explain how water shortage could have an indirect effect on photosynthesis by influencing the ability of carbon dioxide
closing of stomata,as guard cells become flacid, slowsdown transpiration/diffusion of water through stomata =thiscan also restrict CO2 intake
68
if the light is switched off, the calvin cycle stops. explain
it stops (ADD) not finished

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