Zusammenfassung der Ressource
B2 Revision
- Cell Organelles
- Nucleus - controls activities
of the cell
- 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