Biology Flashcards
Pathogen
microorganism which causes infectious disease
Malnutrition
Getting too much or too little of a particular nutrient in your diet
Health
A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity
Disease
Any deviation from the normal structure or function of a body part, organs, or system that is manifested by a characteristic set of symptoms
Species
A group of similar and closely related organisms that can breed together to produce fertile offspring
Pest
Considered to be any organism, plant or animal, that causes nuisance or harm
Fertilisers
Chemicals used to replace the minerals taken out of the soil by crops
Alleles
Two different forms of the same gene
Co-dominance
A form of dominance wherein the alleles of a gene pair in a heterozygote both affect the phenotype
Phenotype
Physical expression of alleles
Genotype
Description of the pair of alleles present for a characteristic
Nucleotide
a monomer made up of a sugar, a phosphate group and a base, which forms the structure of DNA
Chromosome
One DNA molecule tightly wrapped around proteins
Test for starch
Add iodine
orange/brown →blue-black
Hazard: Iodine is irritant so avoid contact and wear safety goggles
Test for reducing sugars
Add distilled water, then Benedict’s solution, then put into water bath (>60℃)
Blue →green, yellow, orange, brick red (in order of more reducing sugars present)
Hazard: when test tube is in water bath, it may bubble into your face so keep it tilted away and wear safety goggles
Hazard: Benedict’s solution is irritant so avoid contact and wear safety goggles
Preparing food samples
Mush into paste using mortar and pestle, and few drops of distilled water
Stir paste with more distilled water in beaker
Filter solution to remove excess solid (except for lipids test as lipids can stick to filter paper)
Test for lipids
(Emulsion test)
Add a few drops of ethanol and distilled water
Clear→ milky-white emulsion
Danger: ethanol is highly flammable so keep naked flames away
Note: do not filter food sample as lipids can stick to filter paper
NB: lipids are soluble in alcohols
Test for proteins
Add distilled water, then biuret solution
Blue → purple (more intense purple = more protein)
Hazard: Biuret solution is irritant so avoid contact and wear safety goggles
Test for non-reducing sugars
Do reducing sugars test - if negative:
Add distilled water, then dilute hydrochloric acid, put into water bath(>60℃), add sodium hydroxide (to neutralise as Benedict’s doesn’t work in acidic solutions), add benedict’s solution, put back into water bath
Blue →green, yellow, orange, brick red (in order of more reducing sugars present)
Hazard: when test tube is in water bath, it may bubble into your face so keep it tilted away and wear safety goggles
Hazard: Benedict’s solution and hydrochloric acid are irritant so avoid contact and wear safety goggles
Telophase
new nuclear membranes form around the two groups of chromosomes at each pole
(5th stage of mitosis)
Anaphase
spindles fibres begin to contract and the chromatids are pulled apart and move to opposite poles of cell
(4th stage of mitosis)
Metaphase
spindle fibres pull the chromosomes to line up on cell’s equator
(3rd stage of mitosis)
Interphase
DNA in nucleus is indistinguishable, and organelles & chromosomes are replicated
(1st stage of mitosis)
Prophase
Chromosomes shorten and thicken and become visible
Nuclear envelope dissipates, spindles fibres form, starting at the poles of the cell and attached to chromosome at the centromere
(2nd stage of mitosis)
