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BIOLOGY PAPER 4 BASIC NOTES
TOPIC 5:
5A: Chlorophylls:
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CHLOROPHYLL A:
- Blue-green pigment in all green plants

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CHLOROPHYLL B:
- Yellow-green pigment

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CAROTENOIDS:
- Orange carotene & yellow xanthophyll

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PHEOPHYTIN:
- Grey pigment caused by the breakdown of other photosynthetic pigments

5A: Absorption VS Action Spectrum:
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ABSORPTION SPECTRUM:
- Graph showing the amount of light absorbed
- Light against wavelength of light

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ACTION SPECTRUM:
- Graph showing the rate of photosynthesis against wavelength of light

5A: Plant Definitions To Learn:
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GRANA:
- Stack of thylakoids within a chloroplast

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THYLAKOIDS:
- Membrane discs found in the grana of chloroplasts

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LAMELLAE:
- Extensions of the thylakoid membrane

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STROMA:
- The “matrix” surrounding grana & contains enzymes for the Calvin Cycle
& produces glucose

5B: Ecology Definitions:
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ABIOTIC PHASE:
- Inorganic ions are returned to the nonliving parts of the ecosystem

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ALLOPATRIC SPECIATION:
- An evolutionary process where populations become geologically or
physically isolated

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ANTHROPOGENIC:
- Caused by humans

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BIOTIC PHASE:
- Inorganic ions are incorporated into the tissues of living things

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CARBON SINK:
- A reservoir where CO₂ is removed from the atmosphere & locked into
organic/inorganic compounds

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CLIMATIC CLIMAX COMMUNITY:
- One possible climax community per climate

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CLIMAX COMMUNITY:
- Biodiversity & range of species is generally constant and self-sustaining

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COMMUNITY:
- All populations of all species of organisms live in a habitat at one time

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EDAPHIC FACTORS:
- Factors relating to soil structure

-

FOOD CHAIN:
- A simple way of modelling feeding relationships in an ecosystem

-

GROSS PRIMARY PRODUCTIVITY (GPP):
- The rate light from the sun catalyses the production of new plant material
- Measured in g m⁻² year⁻¹

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NET PRIMARY PRODUCTIVITY (NPP):
- The material produced by photosynthesis & stored as new plant material
- EQUATION: GPP - R

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NICHE:

-

The role of an organism within the habitat it lives in

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POPULATION:
- A group of organisms, of the same species, living and breeding together
in a habitat

-

PYRAMID OF BIOMASS:
- Represents the biomass of organisms at each trophic level in a food chain
- Dry biomass is the most accurate

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PYRAMID OF ENERGY:
- Represents the total energy store of organisms at each trophic level in a
food change
- Makes observations over time

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PYRAMID OF NUMBERS:
- Represents the number of organisms at each trophic level in a food chain
- Not accurate but it’s easier to collect the data

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SUCCESSION:
- A process where communities of organisms colonising an area changes
over time

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SYMPATRIC SPECIATION:
- An evolutionary process when organisms are reproductively isolated by
mechanical, behavioural or seasonal changes

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TEMPERATURE COEFFICIENT (Q₁₀):
- Shows the effect of temperature on rate of reaction
- Q₁₀ for any reaction at 0-40C = 2
- A 10C increase causes the reaction to DOUBLE

TOPIC 6:
6A: Entering the Gut:
1
...
STOMACH:
- HCl (hydrochloric) acid has a pH of 2
- Destroys most microorganisms

3
...
VECTORS:
- Living organisms that transfers infection from 1 host to another
- Eg
...
INHALATION:
- Droplets contain pathogens that can be inhaled and make you sick
3
...
salmonella, diarrhoea, etc
...
FOMITES:
- Inanimate objects that carry the pathogen
- Eg
...
DIRECT CONTACT:
- Crucial in spread of skin diseases in children
- Also in sexually transmitted infections
- Eg
...
INOCULATION:
- Pathogens spread through a break of skin
- Sexually contaminated medical instruments
- Eg
...
SKIN:
- A tough physical barrier containing keratin
- Physical barrier between pathogens & blood under skin
2
...
SKIN FLORA:
- Successfully competes for space on skin
- Produces chemicals to inhibit microorganism growth

6A: YM Media & MacConkey Agar:
-

YM MEDIA:
- Low pH
- Encourages the growth of fungi & mould

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MACCONKEY AGAR:
- Encourages the growth of gram-negative bacteria

6B: Leucocytes:
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Larger the erythrocytes
Formed in the bone marrow
Defends the body against infection
All have a nucleus & a colourless plasma
- Some have granules

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Types:
- AGRANULOCYTES:
- Lymphocytes
- Monocytes
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GRANULOCYTES:
- Basophils
- Eosinophils
- Neutrophils

6B: Granulocytes:
-

Contains granules
Contain nuclei and round projections
Non-specific Response
3 types:
- BASOPHILS:
- 2 lobed nuclei

-

Produces histamines

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EOSINOPHILS:
- Stained red by EOSIN STAIN
- Important against parasites, allergies, inflammation, etc
...
Paternity tests

-

IDENTIFYING & CLASSIFYING ORGANISMS:
- DNA profiles are unique to individuals
- Similarities & differences indicate the relatedness between individuals &
species
- Extrons tend to be used here



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