biology Flashcards
recall the following reagents and their colour changes
Benedict’s
Iodine solution
Biuret
Ethanol
Benedict’s Blue —> Brick red precipitate
Iodine solution Yellow–brown —> Blue–black
Biuret Blue —> Lilac/Purple
Ethanol Colourless —> White emulsion
Equation for
respiration
glucose + oxygen —-> energy + carbon dioxide + water
C6H12O6 + 6O2 —-> energy + 6CO2 + 6H2O
Aerobic and
anaerobic
respiration
in mammalian muscle
glucose —> energy + lactic acid
and in yeast
glucose —> energy + alcohol + carbon dioxide
demonstrate knowledge and understanding
respiration
reaction that is exothermic, taking
place in mitochondria, continuously releasing energy
in all cells that organisms can use for heat, movement,
growth, reproduction and active uptake/transport
what is photosynthesis
endothermic process that takes
place in chloroplasts, where chlorophyll absorbs light
energy and produces sugars and starch;
the word equation for photosynthesis
Carbon dioxide + water + (light energy) —> glucose + oxygen
the balanced chemical equation for photosynthesis
6CO2+6H2O→C6H12O6+6O2
what is required for photosynthesis
light, carbon dioxide and chlorophyll
Photosynthesis Limiting factors
temperature, light intensity and
carbon dioxide concentration
how the relationship between photosynthesis
and respiration affects the gas exchange between
organisms and their environment
the colour changes of
hydrogencarbonate indicator (high CO2 – yellow,
normal CO2 – red and low CO2 – purple)
* compensation point
Eutrophication is
Eutrophication
Eutrophication is a type of water pollution caused by the addition of sewage or fertiliser.
How do plants absorb minerals
plants absorb minerals from the soil through root
hair cells by active uptake/transport
Carbon cycle is
Photosynthesis -> Respiration -> Combustion (burning)
Carbon dioxide -> Glucose -> Fuel
Glucose -> Carbon dioxide -> Carbon dioxide
Nitrogen fixation is
Nitrogen gas is converted into
nitrates
This is carried out by nitrogen fixing bacteria.
Nitrogen fixing bacteria need oxygen as they are
aerobic
This process is quickened by the presence of oxygen and higher temperatures.
Process of Decomposition
Bacteria/fungi break down protein found in dead plants and animals, urine and faeces into ammonia.
What is phototropism
phototropism
* auxin produced at the tip of the shoot;
* auxin moving down the shoot;
* light causing uneven distribution of auxin; and
* auxin causing cell elongation, which results in
bending of the shoot.
what is diabetes
- diabetes is a condition in which the blood glucose
control mechanism fails
what is type 1 diabetes
pancreas stops producing insulin, which then has to
be taken as medication throughout life
* Type 1 diabetes usually occurs early in life
what is type 2 diabetes
- Type 2 diabetes is when the pancreas
gradually produces less insulin, which in early
stages means it can be controlled by diet but later
may also require insulin injections;
symptoms of diabetes
- the symptoms of diabetes include high blood
glucose, glucose in the urine, lethargy and thirst
- the number of people with diabetes in the
population is rising and evaluate why
obesity is closely linked to the increasing prevalence of diabetes
explain the structure of central nervous system
the brain and
spinal cord together form the central nervous system
that controls and co-ordinates the responses between
the receptors and effectors, and muscles;
Reflex arc
what is a reflex arc
The nerve pathway followed by a reflex action is called a
reflex arc.
For example, a simple reflex arc happens if we accidentally touch something hot.
what is active uptake
active uptake/transport is a process that requires
energy from respiration to transport the minerals
against a concentration gradient;
Explain the steps for The starch test
- Place the leaf in boiling water for 30 seconds - this kills it, stopping any
further chemical reactions. - Place the leaf in boiling ethanol 0 - removes the chlorophyll making the
leaf paler in colour. - Dip the leaf in water - this softens it.
- Spread the leaf onto a white tile and add iodine 0 to test for the presence
of starch.
Results:
If starch is present the iodine will change from yellow-brown to blue-black. If starch is absent the iodine will remain yellow-brown.
Explain the sewage run-off in eutrophication
The sewage or fertiliser run-off increases the nitrate concentration of the water and has a negative effect on the aquatic
ecosystem
Name the small pores on the surface of a leaf that allow gases to enter.
Stoma or Stomata
Describe the function of the intercellular air spaces in a leaf.
movement of gases
factors that affect the rate of enzyme activity
pH;
temperature;
enzyme concentration;
substrate concentration
Stages of nitrogen cycle
- Nitrogen-fixation
- Feeding
- Production of nitrogenous waste products
- Decomposition
- Nitrification
- Uptake of nitrates
- Denitrification
