biology 102 module 5 ( 2 versions)
questions with detailed answers
How do the skeletal muscles and liver respond to maintain body temperature?
Skeletal muscles contract to release heat
Rate of respiration increases in order to release energy for muscle contraction, also
releasing heat
Liver can increase or decrease its rate of respiration to increase or decrease the energy
from food that is converted to heat
What is a stimulus?
A change in the environment
What is a response?
the reaction to a stimulus - it can be an action or behavior
Why do we need communication systems?
survival and activity, threats from changing environments and coordination of different
organs
Why are communication systems so important for multicellular organisms?
cells need to communicate over long distances and organ systems must coordinate
responses
How do plants respond to stimuli?
By using plant hormones.
Which two communication systems do we have?
neuronal and hormonal
Characteristics of nervous system signal
an electrical impulse (action potential)
fast (milliseconds)
short lasting
Characteristics of endocrine system signal
chemical messenger - through blood
slower
long lasting
What is autocrine signaling?
cell signals itself
What is paracrine signaling?
cell signals nearby cell
What is contact dependent signaling?
membrane-bound signals bind to receptors on adjacent cells
How does cell signaling work?
A signaling cell will send a signal out to a receptor cell. The receptor cell will bind to the
signal, which causes a response inside the cell.
What is summation?
the process of adding up postsynaptic potentials and responding to their net effect
What is temporal summation?
,If multiple impulses arrive within quick succession the effect of the impulses can be
added together to generate an action potential
What is spacial summation?
multiple impulses arriving simultaneously at different synaptic knobs stimulating the
same cell body can also generate an action potential
What is the purpose is excitatory neurotransmitters?
stimulate an action potential in the postsynaptic neurone by opening sodium ion
channels in the post synaptic membrane which causes depolarisation if threshold is
reached
What is the purpose of inhibitory neurotransmitters?
prevent the generation of an action potential by opening potassium ion channels in the
post synaptic membrane which causes hyperpolarisation
What happens if the neurone experiences both excitatory and inhibitory synapses
at the same time?
sodium ions enter the cell body and potassium ions diffuse out, canceling out the effect
of the sodium ions entering
threshold potential is not reached so no action potential is generated
What is photosynthesis?
light energy is transformed into chemical energy
Which organisms can photosynthesise?
autotrophs
What can glucose be converted into by plants?
starch, amino acids, cellulose, nucleic acids
What is a photon?
a particle of light
How much energy does one photon contain?
a quantum
Is photosynthesis endothermic or exothermic?
endothermic
What is the purpose of the waxy cuticle?
limits water loss
What is the purpose of the upper epidermis?
protect leaf from injury and reduce water loss
What is the purpose of the palisade cells?
contain a large number of chloroplasts and are adapted for efficient photosynthesis
What is the purpose of the lower epidermis?
some cells of the lower epidermis are modified to form guard cells which control the
movement of water and gases in and out of the lead - also protects the leaf
What is the purpose of the spongy mesophyll?
contain less chloroplasts than palisade cells
air spaces between cells play a role in gas exchange
What is the relationship between photosynthesis and respiration?
allow the cycling of carbon dioxide and oxygen
the products of one process are the raw materials for the next
,What is the compensation point?
The level of light intensity at which the rate of photosynthesis exactly matches the rate
of respiration
What occurs at the compensation point?
there is no net gain or loss of carbohydrate
What is the time taken to reach the compensation point called?
the compensation period
What are thylakoids?
pigment containing flattened discs
the light dependent reaction takes place in the thylakoid membrane
What is a granum?
stack of thylakoids
provide the chloroplast with an increased surface area for photosynthesis to occur in
limited space
What are lamellae?
extensions of the membrane that form the thylakoids
they connect one granum to another
site of light dependent reaction
What is the stroma?
amorphous, gel-like material containing enzymes
light independent reaction occurs here using these enzymes
What is the double membrane of the chloroplast?
controls molecular traffic into and out of the chloroplast
inner membrane is extensively folded to form thylakoids
What other 3 things does the stroma contain?
1) starch grains
2) oil droplets
3) small ribosomes
What's the purpose of starch grains?
store the glucose produced in photosynthesis
What's the purpose of oil droplets ?
provide the raw materials for making new membranes
What's the purpose of small ribosomes?
to produce the proteins coded for by the chloroplast DNA
What is the role of pigments?
absorb specific wavelengths of light and reflect others
What is chlorophyll a?
the primary pigment in photosynthesis
Which colours does chlorophyll a absorb?
mainly red and blue
Which colours does chlorophyll a reflect?
green
What are the accessory pigments ?
chlorophyll b, carotenoids, xanthophylls
What is the purpose of accessory pigments?
pass energy to primary pigments in reaction centre
, What do carotenoids mainly absorb?
blue and green light
What do carotenoids mainly reflect?
red, orange and yellow light
Where does the light dependent reaction take place?
the thylakoid membrane of the chloroplasts
What is the role of the photosystem?
to absorb light energy of different wavelengths and transfer this energy efficiently and
quickly to the reaction centre
What do the antenna complexes consist of?
chlorophyll b, chlorophyll a, carotenoids and xanthophyll
What is chlorophyll a P680?
found in photosystem II and has a peak absorption of 680nm
What is chlorophyll a P700?
found in photosystem I and has a peak absorption of 700nm
What wavelengths of light does chlorophyll b absorb?
400-500nm and around 640nm
What colour does chlorophyll b appear?
yellow-green
What are the wavelengths that carotenoids absorb?
400-500nm
What colours do xanthophylls absorb?
blue and green
What wavelengths of light do xanthophylls absorb?
375-550nm
What colours do xanthophylls reflect?
yellow
What is the advantage of having a range of pigments?
the plant uses a range of different wavelengths to harvest the maximum amount of
energy
How do accessory pigments work?
1) light energy arrives in the form of photons which excite electrons in the pigments
2) there is a transfer of energy from one accessory pigment to the next until energy
reaches the reaction centre
3) here there is an electron acceptor to commence the two stages of photosynthesis
Why do leaves change colour in autumn?
The pigment chlorophyll is broken down into colourless
compounds
This process allows other pigments in the leaf to be seen
Anthocyanins, carotenes, xanthophylls - produce the reds,
yellows and oranges seen in autumn leaves
The leaf is also drained of all useful substances before
abscission
What is in ATP?
a sugar (ribose), a base (adenine), and three phosphate groups
What is the term used to describe the breakage of bonds in ATP?
questions with detailed answers
How do the skeletal muscles and liver respond to maintain body temperature?
Skeletal muscles contract to release heat
Rate of respiration increases in order to release energy for muscle contraction, also
releasing heat
Liver can increase or decrease its rate of respiration to increase or decrease the energy
from food that is converted to heat
What is a stimulus?
A change in the environment
What is a response?
the reaction to a stimulus - it can be an action or behavior
Why do we need communication systems?
survival and activity, threats from changing environments and coordination of different
organs
Why are communication systems so important for multicellular organisms?
cells need to communicate over long distances and organ systems must coordinate
responses
How do plants respond to stimuli?
By using plant hormones.
Which two communication systems do we have?
neuronal and hormonal
Characteristics of nervous system signal
an electrical impulse (action potential)
fast (milliseconds)
short lasting
Characteristics of endocrine system signal
chemical messenger - through blood
slower
long lasting
What is autocrine signaling?
cell signals itself
What is paracrine signaling?
cell signals nearby cell
What is contact dependent signaling?
membrane-bound signals bind to receptors on adjacent cells
How does cell signaling work?
A signaling cell will send a signal out to a receptor cell. The receptor cell will bind to the
signal, which causes a response inside the cell.
What is summation?
the process of adding up postsynaptic potentials and responding to their net effect
What is temporal summation?
,If multiple impulses arrive within quick succession the effect of the impulses can be
added together to generate an action potential
What is spacial summation?
multiple impulses arriving simultaneously at different synaptic knobs stimulating the
same cell body can also generate an action potential
What is the purpose is excitatory neurotransmitters?
stimulate an action potential in the postsynaptic neurone by opening sodium ion
channels in the post synaptic membrane which causes depolarisation if threshold is
reached
What is the purpose of inhibitory neurotransmitters?
prevent the generation of an action potential by opening potassium ion channels in the
post synaptic membrane which causes hyperpolarisation
What happens if the neurone experiences both excitatory and inhibitory synapses
at the same time?
sodium ions enter the cell body and potassium ions diffuse out, canceling out the effect
of the sodium ions entering
threshold potential is not reached so no action potential is generated
What is photosynthesis?
light energy is transformed into chemical energy
Which organisms can photosynthesise?
autotrophs
What can glucose be converted into by plants?
starch, amino acids, cellulose, nucleic acids
What is a photon?
a particle of light
How much energy does one photon contain?
a quantum
Is photosynthesis endothermic or exothermic?
endothermic
What is the purpose of the waxy cuticle?
limits water loss
What is the purpose of the upper epidermis?
protect leaf from injury and reduce water loss
What is the purpose of the palisade cells?
contain a large number of chloroplasts and are adapted for efficient photosynthesis
What is the purpose of the lower epidermis?
some cells of the lower epidermis are modified to form guard cells which control the
movement of water and gases in and out of the lead - also protects the leaf
What is the purpose of the spongy mesophyll?
contain less chloroplasts than palisade cells
air spaces between cells play a role in gas exchange
What is the relationship between photosynthesis and respiration?
allow the cycling of carbon dioxide and oxygen
the products of one process are the raw materials for the next
,What is the compensation point?
The level of light intensity at which the rate of photosynthesis exactly matches the rate
of respiration
What occurs at the compensation point?
there is no net gain or loss of carbohydrate
What is the time taken to reach the compensation point called?
the compensation period
What are thylakoids?
pigment containing flattened discs
the light dependent reaction takes place in the thylakoid membrane
What is a granum?
stack of thylakoids
provide the chloroplast with an increased surface area for photosynthesis to occur in
limited space
What are lamellae?
extensions of the membrane that form the thylakoids
they connect one granum to another
site of light dependent reaction
What is the stroma?
amorphous, gel-like material containing enzymes
light independent reaction occurs here using these enzymes
What is the double membrane of the chloroplast?
controls molecular traffic into and out of the chloroplast
inner membrane is extensively folded to form thylakoids
What other 3 things does the stroma contain?
1) starch grains
2) oil droplets
3) small ribosomes
What's the purpose of starch grains?
store the glucose produced in photosynthesis
What's the purpose of oil droplets ?
provide the raw materials for making new membranes
What's the purpose of small ribosomes?
to produce the proteins coded for by the chloroplast DNA
What is the role of pigments?
absorb specific wavelengths of light and reflect others
What is chlorophyll a?
the primary pigment in photosynthesis
Which colours does chlorophyll a absorb?
mainly red and blue
Which colours does chlorophyll a reflect?
green
What are the accessory pigments ?
chlorophyll b, carotenoids, xanthophylls
What is the purpose of accessory pigments?
pass energy to primary pigments in reaction centre
, What do carotenoids mainly absorb?
blue and green light
What do carotenoids mainly reflect?
red, orange and yellow light
Where does the light dependent reaction take place?
the thylakoid membrane of the chloroplasts
What is the role of the photosystem?
to absorb light energy of different wavelengths and transfer this energy efficiently and
quickly to the reaction centre
What do the antenna complexes consist of?
chlorophyll b, chlorophyll a, carotenoids and xanthophyll
What is chlorophyll a P680?
found in photosystem II and has a peak absorption of 680nm
What is chlorophyll a P700?
found in photosystem I and has a peak absorption of 700nm
What wavelengths of light does chlorophyll b absorb?
400-500nm and around 640nm
What colour does chlorophyll b appear?
yellow-green
What are the wavelengths that carotenoids absorb?
400-500nm
What colours do xanthophylls absorb?
blue and green
What wavelengths of light do xanthophylls absorb?
375-550nm
What colours do xanthophylls reflect?
yellow
What is the advantage of having a range of pigments?
the plant uses a range of different wavelengths to harvest the maximum amount of
energy
How do accessory pigments work?
1) light energy arrives in the form of photons which excite electrons in the pigments
2) there is a transfer of energy from one accessory pigment to the next until energy
reaches the reaction centre
3) here there is an electron acceptor to commence the two stages of photosynthesis
Why do leaves change colour in autumn?
The pigment chlorophyll is broken down into colourless
compounds
This process allows other pigments in the leaf to be seen
Anthocyanins, carotenes, xanthophylls - produce the reds,
yellows and oranges seen in autumn leaves
The leaf is also drained of all useful substances before
abscission
What is in ATP?
a sugar (ribose), a base (adenine), and three phosphate groups
What is the term used to describe the breakage of bonds in ATP?
