Cell Membrane -
controls
activity/passages in
and out of the cell
Cytoplasm
- where
chemical
reactions
take place
Ribosomes -
protein
synthesis of
molecules
Mitochondria -
where respiration
occurs
Cell Wall -
supports the
cell
Vacuole -
contains cell sap
Chloroplasts - absorb
light energy to be used
in photosynthesis
Other Cells
Yeast
single-celled, no cellulose, cannot
photosynthesis because it has no
chloroplasts
Bacteria
no nucleus -
floating DNA
Algae
similar to
plant cells
Viruses
sphere of
protein
Diffusion
spreading of particles from
high to low concentrations
oxygen
diffuses
larger concentration
gradient = faster
diffusion
Tissues
Muscular
predominantly
needed for movement
- lots of mitochondria
in cells, used in
respiration for
contraction
Glandular
cells secrete enzymes
and hormones from
vesicles
Multi-cellular
many different cells;
specialised
Plant Features
Xylem - carries water
from root to leaf
Phloem - transport of sugars
Epidermal Tissue has holes
(stomata) which allows gases
to diffuse
Limiting Factors -
Light, CO2,
Temperature
Enzymes
Amylase -
breaks down
starch into
simple sugars
Produced in
pancreas and salivary
glands
Used in sugar syrup -
starch changed to sugar
by adding amylase (
carbohydrase )
Protease - breaks
down proteins into
amino acids
Produced in pancreas,
stomach and small
intestine
Used in baby food to break
down large proteins into
amino acids, so that babies
can absorb the AA at ease.
Lipase - breaks down fats
and lipids into fatty acids
and glycerol
Produced in pancreas
and small intestine
Isomerase used to
turn glucose into
fructose - sweeter,
so less is needed and
is consequently used
in slimming foods.
Aerobic Respiration
oxygen+glucose=carbon
dioxide+water+(energy)
Glycogen stores are broken down
into glucose for respiration
respiration releases energy which
increases body temperature
amino acids can be made from
nitrate and sugar ions
Anaerobic Respiration
glucose=lactic
acid+(little energy)
Carried out when insufficient
oxygen supplies
Oxygen debt removes lactic
acid build up
Mitosis - cell division
into TWO
provides cells for
growth/repair
Copies made, particles then line up at the
middle of the cell, identical copies then split
moving to opposite sides of the cell. 2 new
daughter cells are made. Chromosomes
form 2 nuclei, alongside new cell
membranes forming.
1 division, 2 cells made, same
number of chromosomes as original,
creates new body cells, all body parts
Meiosis
Copies made, cell division
happens twice creating 4
daughter cells. Therefore,
new cells are only provided
with half the original
number of chromosomes.
2 divisons, 4 cells made, 1/2
number of chromosomes as
original, gametes, testes and
ovaries
homologous pairs
Stem Cells
have the ability to develop into
any type of cell
most cells differentiate, forming
specialised cells
In plants, cells can differentiate at
any time
Genes
have different forms
Alleles
Mendel worked with allele
factors in his pea pollination
humans have 2 sets of
chromosomes in each
cell
DNA is always different
Fossils
Bones and teeth do not
easily decay
Some parts of
organisms do not decay
because conditions are
not suitable for this to
happen
Parts of organisms may be
replaced by other materials
such as hard minerals as
they decay
Traces of an organism
may be preserved in
rocks as prints
Extinction
Change in environment
New predators
New diseases
More succesful competitors
New species/Speciation
1. Geographical isolation
Few lizards drift away from the
mainland on floating logs and end
up on an island. Isolated from rest
of species.
2. Genetic Variation
In both mainland and island
lizards, different alleles of genes
which lead to variation.
3. Natural Selection
Environment, predators etc on mainland are dif from
those on island. Natural selection takes place and dif
features are selected.
4. Speciation
Over time, more and more difs build
up between two populations until they
are no longer the same species