5.6 Flashcards
what organisms use photosynthesis to convert light energy from sunlight into chemical energy
photosynthesis is used by plants, algae and some types of bacteria to convert light energy from sunlight into chemical energy
what is autotrophic nutrition
organisms using chemical energy to synthesise large organic molecules, which form the building blocks of living cells, from simple organic molecules such as water and carbon dioxide
what are photoautotrophs
organisms that photosynthesise and use light as the energy source for autotrophic nutrition.
what can photoautotrophs also be called
photoautotrophs can also be called producers
photoautotrophs can also be called producers, why are they also called producers
because they are at the beginning (first trophic level) of a food chain and provide energy and organic molecules to other non-photosynthetic organisms.
state the general balanced equation for photosynthesis
6CO2 + 6H20 —chlorophyll—> C6H12O6 +6O2
whats a photon
a photon is a particle of light; each photon contains an amount (a quantum) of energy
what is the main product for photosynthesis
the main product of photosynthesis is a monosaccharide sugar which can be converted to a disaccharide for transport then starch for storage
what is carbon fixation and give an example
carbon fixation is the process by which carbon dioxide is converted to sugars
the carbon for synthesising all types of organic molecules is provided by carbon fixation
-photosynthesis is an example of carbon fixation.
is carbon fixation exothermic or endothermic
-endothermic so needs energy
-carbon fixation also needs electrons ( a reduction reaction)
what can carbon fixation help regulate
-carbon fixation helps regulate the conc. of CO2 in the atmosphere and oceans
is respiration an oxidation or reduction reaction
oxidiation
how do photoautotrophs respire
organic molecules are oxidised that have been previously synthesised by by photosynthesis and stored releasing chemical energy
examples of non-photosynthetic organisms
-fungi, animals, many protists and many types of bacteria
what are heterotrophs
-non-photosynthetic organisms that obtain food by consuming other living things.
-they cannot make their own food
how do heterotrophs obtain energy
-heterotrophs obtain energy by digesting complex organic molecules of food to smaller molecules that they can use as respiratory substrates.
-they obtain energy from the products of digestion by respiration
how do heterotrophs respire
during respiration, glucose and other organic compounds are oxidised to produce CO2 and water.
respiration releases chemical energy (exothermic) that can drive an organisms metabolism
what is the general equation for respiration
C6H12O6 + 6O2 –> 6H2O + 6CO2 + ENERGY
how does photosynthesis and respiration relate
the product of one process are the raw materials for the other process; aerobic respiration removes oxygen from the atmosphere and adds CO2, while photosynthesis does the opposite
how often do plants respire
all the time
how often do plants photosynthesise
only when sunlight available
when is the compensation point
when photosynthesis and respiration proceed at the same rate, so that there is no net gain or loss of carbohydrates, the plant is at its compensation point
whats the compensation period
the time a plant takes to reach its compensation point is the compensation period
why do shaded plants reach their compensation point quicker than sun plants?
shade plants utilise light at a lower intensity thank sun plants.
do algae or photosynthetic bacteria have chloroplasts
algae do
how long are chloroplasts
2-10um
what is the chloroplast envelope
a double membrane which surrounds chloroplasts
what is the intermembrane compartment
the space between the inner and outer membrane. It has a width of 10-20nm between the two membranes
what is the outer membrane
a highly permeable outer layer
what is the inner membrane
a membrane that separates the intermembrane space from the stroma
what are the 2 distinct regions that can be seen in a chloroplast when using an electron microscope
the stroma and the grana
whats the stroma
the fluid filled matrix of chloroplasts where the light-independent stage of photosynthesis takes place
what is contained in the stroma
-enzymes needed to catalyse reactions in the light-independent stage of photosynthesis
-starch grains
-oil droplets as a source of lipids to make membranes
-ribosomes for protein synthesis of enzymes/ electron carriers/ anchoring proteins
-DNA which contain genes needed for photosynthesis
whats the granum
the inner part of chloroplasts made of stacks of thylakoid membranes, where the light dependent stage of photosynthesis takes place
what stage of photosynthesis takes place in the grana
the first stage if photosynthesis (the light dependent stage)
what are the 3 distinct membranes that chloroplasts have
-outer, inner and thylakoid, this gives 3 separate internal compartments
what are the three separate internal compartments in the chloroplast
-the intermembrane space
-the stroma
-the thylakoid space
what may the thylakoids within the granum be connected to
they may be connected to another granum by intergranal lamellae (also known as intergranal thylakoids )
mention the permeability of the thylakoid membrane
less permeable
what is each stack of thylakoids called
a granum
what is the advantage of many Grana in every chloroplast and with many chloroplasts in each photosynthetic cell
there is a large surface area for:
-photosystems that contain photosynthetic pigments to trap sunlight
-electron carriers an ATP synthase enzymes needed to convert light energy into ATP
whats a thylakoid
a flattened membrane-bound sac found inside chloroplasts; contain photosynthetic pigments/photosystems and is the site of the light dependent stage of photosynthesis.
whats the intergranal lamellae
an interconnection that allows separate grana to be interconnected.
what hold photosystems in place
proteins embedded in thylakoid membranes
why are the grana surrounded by the stroma
so the products of the light dependent stage can easily pass to the stroma to be used in the light-independent stage
what are photosystems
a funnel-shaped cluster of photosynthetic pigments found in the thylakoid membranes witch act as the light-collecting units of the chloroplast
the primary reaction centre is a molecule of Chlorophyll A at the base of the photosystem
accessory pigments consist of of Chlorophyll B and Carotenoids which lie on the wall of the photosystem
talk abt the reflection and absorption of photosynthetic pigments and how it appears to our eye
each pigment absorbs certain light and reflects others. Each pigment appears to our eyes and brain, the colour of the wavelength its reflecting
what are photosynthetic pigments
a pigment that absorbs specific wavelengths of light and reflects other pigments
how do photosystems work
the energy associated with the wavelengths of light captured is funnelled down to the primary pigment reaction centre, consisting of a type of chlorophyll, at the base of the photosystem.