Unit 5 Flashcards
What is the source of energy for an ecosystem?
sunlight
What is the role of producers in an ecosystem?
Producers are plants that perform photosynthesis and use light energy to make biological molecules.
What is the role of consumers in an ecosystem?
Consumers are animals that cannot make their own biological molecules and need to eat plants (primary consumers) or other animals (secondary/tertiary consumers) to obtain biological molecules.
What is the role of decomposers in an ecosystem?
Decomposers are bacteria and fungi that perform saprobiotic decomposition, releasing enzymes onto dead plants, dead animals, and animal waste to break them down and obtain biological molecules.
Why do producers (plants) need biological molecules?
Producers need biological molecules for respiration (glucose), storage (starch), and to make cellulose and proteins (amino acids).
Why do consumers (animals) need biological molecules?
Consumers need biological molecules for respiration (glucose), storage (glycogen), and to make triglycerides (fatty acids and glycerol) for energy and protection.
Why do decomposers (bacteria/fungi) need biological molecules?
Decomposers need biological molecules for respiration (glucose), to make proteins (amino acids), and to form phospholipids (fatty acids and glycerol).
How do organisms carry energy?
Energy is mainly carried as glucose, stored as starch in plants and glycogen in animals, with alternative sources being lipids/fats/triglycerides and proteins.
How does energy move through an ecosystem?
Energy moves through the food chain, starting with producers and moving to primary consumers, then secondary and tertiary consumers, with decomposers at each trophic level.
Why is all the light energy not utilized by plants in photosynthesis?
Only 2% of light energy is used in photosynthesis; some light misses the chloroplast, is reflected, or is of the wrong wavelength.
Why is energy lost along a food chain?
Energy is lost due to respiration (as heat), inedible and indigestible parts of organisms, and only 10% of energy is transferred from producer to primary consumer.
What is Productivity?
Productivity is the amount of glucose/energy available to organisms, with primary productivity referring to plants and secondary productivity to animals.
What does a Pyramid of Number represent?
It represents the number of each type of organism at each trophic level, decreasing as we move up due to energy loss.
What does a Pyramid of Biomass represent?
It represents the biomass of each type of organism at each trophic level, with biomass being the mass of living tissue.
What does a Pyramid of Energy represent?
It represents the amount of energy found at each trophic level, with energy loss occurring along the food chain.
What are the units for energy?
kJ/m2/year
What is photosynthesis?
Photosynthesis is the process of using light energy to make glucose and other biological molecules, occurring in plants and algae.
What are adaptations of plants for photosynthesis?
Plants have leaves located near the top for light, thin and wide leaves for surface area, veins for water transport, stomata for gas exchange, and palisade cells for maximizing light absorption.
What is the structure of chloroplast?
Chloroplasts have a double membrane, thylakoids containing chlorophyll, granum stacks, and stroma fluid.
How does photosynthesis take place?
Photosynthesis occurs in two stages: the light-dependent stage on thylakoids and the light-independent stage in the stroma.
Describe the light-dependent stage of photosynthesis.
Light hits chlorophyll
chlorophyll absorbs the light if correct wavelength
electrons become excited and are lost from the chlorophyll (photoionisation)
electrons enter an electron carrier system
electrons move down the system releasing energy
this pumps protons from stroma into thylakoid space
protons accumulate in thylakoid space, then diffuse back into stroma
they pass though ATP Synthase which joins ADP and Pi to make ATP (mechanism = chmeiosmosis, process = photophosphorylation)
the electron ends up by joining with NADP to form reduced NADP
light also hits water
causes photolysis (breakdown of water due to light
forms: 4H+, 4e-, O2
the H+ joins with the reduced NADP (now carries a hydrogen atom: H+ and e-)
the e- replaces electrons lost from chlorophyll
O2 given off as waste
Describe the light-independent stage of photosynthesis.
involves the calvin cycle
− RuBP (5 carbon) joins with CO2 to make 2 lots of GP (3 carbon)
− the GP is reduced into TP (3 carbon)
− this uses energy from ATP and hydrogen atom from reduced NADP
− the TP can be used to reform RuBP (uses energy from ATP)
− the TP can also be used to form glucose (carbohydrate)
− GP can also be used to form amino acids (proteins) and fatty acids
− TP can also be used to form glycerol
− fatty acids and glycerol will form a lipid
−photosynthesis/calvin cycle = produces all the main biological molecules
What are the limiting factors for photosynthesis?
The limiting factors are light, CO2, and temperature, which when increased, can raise the rate of photosynthesis.
What is the compensation point in plants?
The compensation point is when the CO2 taken in by photosynthesis equals the amount given out by respiration, resulting in no net gas exchange.
How to measure the rate of photosynthesis?
The rate of photosynthesis can be measured by the amount of CO2 used or O2 produced over a certain time, using a photosynthometer.
How does a photosynthometer work?
− measures amount of O2 produced
− uses aquatic plants (e.g. elodea), as the O2 produced can be observed and collected
− the plant is surrounded in sodium hydrogencarbonate solution (CO2 source)
− the plant is kept in darkness before experiment runs (uses up all the O2 in the plant)
− as the experiment runs, O2 will be produced, this will be collected in a capillary tube
− the amount collected can be measured, this will be converted into a volume by multiplying length of oxygen bubble collected by πr2
− volume of O2 collected can then be divided by time to calculate rate of photosynthesis
What is the structure of ATP?
− Adenosine Triphosphate
− made from 1 adenosine and 3 phosphates
− energy carrier molecule
− formation: ADP + Pi (+ energy used) = ATP
− condensation reaction using enzyme ATP Synthase
− carries energy in its bonds
− breakdown: ATP = ADP + Pi (+ energy released)
− hydrolysis reaction using enzyme ATPase
− delivers energy after breakdown
Nucleotide derivative
How can ATP be formed?
− photophosphorylation (light dependent stage of photosynthesis)
− substrate-level phosphorylation (glycolysis and krebs cycle of respiration)
− oxidative phosphorylation (electron transport chain of respiration)
What makes ATP a good source of energy?
immediate source = need to only break one bond to release energy (plus bond is weak)
manageable source = releases small amount of energy
What are the uses of ATP in organisms?
ATP is used for protein synthesis, organelle synthesis, DNA replication, cell division, active transport, metabolic reactions, movement, and maintaining body temperature.
