Mock March 2020 Flashcards
Transpiration
. Movement of water . From the root through the plant . Through lignified cells dead cells . Of xylem . Driven by evaporation of water . From the leaves . Through the stomata . Flow is only in one direction . By capillary action . According to cohesion - tension theory
Translocation
. Movement of sugars from the leaves . As sucrose . Through living sieve cells . Flow is bidirectional . To sinks in the plant where the sucrose is needed
Inside the leaf top to bottom
Waxy cuticle Upper epidermis Palisade mesophyll Air space Spongy mesophyll Lower epidermis Waxy cuticle Guard cells with chloroplasts Exchange of gases through stomata
Epidermis
Thin transparent
Allows light to reach palisade cells
Thin cuticle made of wax
Protects leaf from infection and prevent loss without blocking out light
Palisade cell
Top of leaf
Absorbs more light and increase rate of photosynthesis
Spongy layer
Air spaces allows arson dioxide to diffuse through the leaf
Chloroplast
Found in palisade layer to absorb available light
Stomata
Allows CO2 to diffuse into the leaf and allow oxygen to diffuse out
Guard cells control opening and closing
Guard cells take in water by osmosis
Osmosis
Diffusion of water molecules, from a region where they are in higher concentration, to a region where they are in lower concentratio
Diffusion
will move in both directions, but there will be a net movement from high to low concentration
will end up evenly spread throughout the liquid or gas but will continue to move
Reducing sugar
. Benedict’s
. Add Benedict’s reagent to the food and boil in a water bath
. Initial colour - blue
. Positive result - brick red precipitate
Starch
. Iodine
. Add iodine reagent to food
. Initial colour - yellow/brown
. Colour of positive result blue-black
Protein/amino acids
. Biuret (a mixture of sodium hydroxide and copper sulphate)
. Add Biuret reagent to the food
. Initial colour - blue
. Positive result - lilac/purple
Fat
Ethanol
Add ethanol to the food to dissolve the fat then add water
Initial colour - colourless
Positive result - white emulsion
Fick’s law
Rate of diffusion is proportional to surface area x concentration difference / thickness of membrane
As surface area increases diffusion…
Increases
As concentration difference increases
Rate of diffusion increases
As membrane thickness increases rate of diffusion
Decreases
10nm
20nm
x2
So
2000 x 1/2 = 1000
10nm
5nm
X0.5
So
2000x1/0.5=4000
10nm
0.016um
0.016um = 16nm
X 1.6
So
2000 x 1/1.6 = 1250
Thermoregulation
Control of the internal body temperature in warm blooded animals. 37 degrees for humans.
thermoregulatory centre
Contained in the hypothalamus in the brain, and it contains receptors sensitive to the temperature of the blood.
Too hot
. Sweat glands release sweat onto skin. The sweat evaporates, transferring heat energy from the skin to the environment.
. Vasodilation - blood vessels get wider increasing blood flow near skin surface
. Blood flow in skin capillaries increases
Too cold
. Shivering releases heat from respiration
. Subantaneous fat insulates
. Hairs stand up trapping insulators layer of air
. Vasoconstriction- blood vessels get narrower reducing blood flow near skin surface
Type 1 diabetes
. Pancreas cells cannot produce insulin because they have been destroyed by the immune system.
. Blood glucose levels increase and can be found in urine
. Treatment = inject with insulin just before eating to convert glucose to glycogen
Type 2 diabetes
. Caused by insulin releasing cells not producing enough insulin or target organs not responding to hormone
. Change in diet/exercise helps
Medicine needed