Unit5 biology content

Qualitative tests identify

Presence of substance

• Reducing and non- reducing sugars

• Proteins

• Starch

• Lipids

Benedict’s risk

Irritation to eyes

• Avoid contact wear goggles

Hydrochloric acid risk

Irritation to skins

• Wear gloved handling

Irritation eyes

• Goggles

Biuret risk

Irritation eyes

• goggles

Corrosive

• Gloved

Iodine risk

Irritation to eyes

• Goggles

Irritation to skin

• Gloves

Boiling water risk

Scalding

• Tongs to transfer tubes goggles

Ethanol risk

Highly flammable

• No naked flames

Reducing sugar test

Add Benedict’s reagent to boiling tube

Heat in water bath 70 degrees 5 mins

Remove observe colour change

Non- reducing sugar test

Add hydrochloric acid hydrolyse non reducing glycosidic bonds

Heat to 70 water bath 2 mins

Cool

Add dilute sodium hydroxide neutralise

Retest with benedicts

Record colour of ppt

Blue → green → yellow → red ppt positive

Test proteins

Add Biuret reagent

Shake to mix

Blue → purple

Starch test

Add iodine KI reagent gently mix

Orange brown → blue black

Lipids test

Add absolute ethanol and equal volume of water

Shake

Emulsion→ Cloudy white

Results of test

Reducing and non

• Blue Green Yellow Orange Brick red

Protein

• Blue Purple

Starch

• Yellow brown Blue black

Lipids

• White cloudy emulsion

Calibration curve

Determine unknown concentration using series of standard samples

Water potential definition

Tendency of water to move from high to low water potential

Why is percentage change in mass calculated instead of the actual change

Varying starting masses percentage allow comparison between discs

Controlled variables of potato osmosis prac

Volume of solution

Size of potato

Length of time in solution

Dap each potato with paper towel

What occurs in plant tissue in hypotonic and hypertonic solution

Hypo - water moves in plant increase mass

Hyper - water moves out decrease mass

Why leave potato in water bath same time

Allow time osmosis reach equilibrium

Plasmolysis and incipient

Retraction of cytoplasms and cell membrane from cell wall water leaves cytoplasm and vacuole

Incipient plasmolysis - water potential of the cytoplasm same as solution no net movement of water

2 factors affect permability of cell membranes

Temperature

Concentration of solvents (ethanol)

How is beetroot used to measure permeability

Higher permeability more red pigment leak within given time

Colorimeter determine absorbance hence concentration of pigment

Temperature effect on permeability

Increased permeability high temp denatures membrane proteins

Gaps in membranes for molecules to pass through

Increase kinetic energy of phospholipids move more

Photosynthesis rate factors

Light intensity

Temperature

Carbon dioxide concentration

Volume of gas produced indicate?

Assumed oxygen, volume of gas proportional to rate

How is light intensity controlled and wavelength and temp

By adjusting distance between light source and the beaker

Using different coloured filters to cover the beaker

Thermostatically controlled water baths

Nitrogen and magnesium role in plant growth - 3 seedinlign groups

Full culture

Culture without magnesium

Culture without nitrates

Why do seedlings need to be dried before weighing

Varying water content dried to allow comparison → dry mass is biomass

Blood vessels attached to kidney

Renal artery and renal vein

Three layers in cross section of a kidney

Cortex medulla and pelivs

Steps to observe tubules in greater detail

Sample from cortex and medulla

Place on slide flatten under cover slip observe low mag

Which type of inheritance shows continuous variation

Polygenic inheritance

Diagrams showing continuous variation and curve

Histogram and bell shaped

Meaning of p= 0.05

5% or less probability that any difference between means is due to chance

Equipment to calibrate

Microscope

Eyepiece graticule

Stage micrometer

Explain why the statistical test chosen was t

• Test if theres a significant difference between the means

• Compare the means of 2 sets of data

Why do some leaves grow in less in high light intensity than others

Larger surface area

More chloroplasts more pigments

more wavelengths of light absorbed

For a test why choose leave taken from single parent plant under same condition

So only difference between measurements due to independent factors

Minimise genetic variation (similar genes and alleles)

Chi squared test χ²

Statistical test to see if the difference between observed and expected results is due to chance or not

χ2 = ∑ (O−E)² / 2​

When would Chi squared test χ² be suitable

Discontinuous data - distinct categories

Comparing observed and expected numebrs

when would quadrats be unsuitable

When organismn is NOT randomly distributed

Why stain

Originally transparent

Stain increases the contrast

Moe valid

Larger sample

Repeat investigation

Same time of year / within a short time

All same heigh /age

Vacuole membrane

Tonoplast