Biology Exam Notes:

Organisms: Characteristics:
- Have cells
- Movement
- Grow
- Reproduce
- Respire (chemical process that provides energy for cells)

Microscope:
- Developed to understand cell structure
- Parts (+ the function of the parts)
- How to prepare a slide
- How to measure cell size

Cell organelles: (structures and their functions)
- Cell wall (mechanical support)
- Nucleus (Stores chromosomes – genetic info + controls cell activity)
- Cell membrane (Controls what chemicals enter/leave)
- Mitochondria (respiration: makes energy available to the cell)
- Cytoplasm (Solution, mostly H2O with dissolved chemicals, location for
many chemical reactions, moves organelles around the cell)

Cell transport:
- Diffusion (Occurs when particles spread. From a region where of high
to low concentration)
- Osmosis (the diffusion of water molecules, higher to lower
concentration, through a partially permeable membrane)
- Active Transport (the movement of dissolved molecules into or out of a
cell through the cell membrane, region of lower to higher concentration)
- Endocytosis (where cells absorb molecules or substances from outside
the cell by engulfing it with the cell membrane.)

DNA Molecule:
-
Section of DNA molecule: Gene
Making new cells (before cell division)
Mitosis: The type of cell division that
produces two daughter cells identical to
the parent cell.
-
Meiosis: The type of cell division that produces gametes with half the
number of chromosomes of the parent cell
Fertilization:

Inheritance:
-Gene: - Section of DNA
- Codes for a characteristic e.g. eye colour
- Can have several different forms (alleles)
4 Types Genetic Problems:

Complete Dominance:
- E.g. Dimples
(Dominant) D: Dimples
(Recessive) d: no dimples
E.g. Genotype = Dd
Phenotype = Dimples
Dd x Dd = 1DD, 2Dd, 1dd (3 dimples, 1 no dimples)
Punnet Square
D
d

D
DD
Dd
d
Dd
dd
Co-dominance (Incomplete):
- One allele does not completely dominate the other
(Gene) Flower Colour
(Alleles) R = Red, r = white
E.g. Genotype = Rr
Phenotype = Pink
Rr x Rr = 1RR, 2Rr, 1rr (1 red, 2 pink, 1 white)
Punnet Square
R
r

R
RR
Rr
r
Rr
rr
Multiple Alleles:
- The gene has more than 2 alleles
E.g. Blood groups (gene)
Alleles: IA
IB
IO
IA IO x IA IB
Punnet Square
IA
IB

IA
IAIA
IAIB
Sex linked:
- The gene occurs on the X or Y chromosome
Gene: Haemophilia
Alleles: H (normal)
h (unable to clot blood)
Punnet Square
XH
Xh

IO
IAIO
IBIO
XHXh x XhYXh
XHXh
XhXh
Pedigree (Family Tree)
Diagram: To show the inheritance of a
particular characteristic in a family
YXHYXhY-

Gene Technology:
1. Genome project (Mapping where genes occurred on human
chromosomes.
2. Gene therapy (Replacing faulty/ diseased genes, replacing with normal
ones
3. Genetic Engineering (Transgenisis or swapping between species)
4. Gene Testing (Testing for the presence of a gene in an individual)
Evolution:

Within a species:
 Evidence:
- Fossils: (Plant or animal dies in a watery environment and is buried in
mud/ silt. Soft tissues decompose until bones/shell. Sediment hardens)
- Comparing anatomy
- Comparing DNA (molecules)
 How:

Variation of inherited characteristics in species
Competition: For (Food, water, nesting sites, sunlight, living space)
Natural Selection: Structure, function, behaviour, environmental factors
Inheritance: Offspring inherited survival characteristics
Evolution: Over a number of generations the proportions of individuals
with high survival features increases.
To form new species:
- Physical (geographical) separation
- Natural selection
- Unable to interbreed (reproductively isolated)