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Mind Map by alisha patel, updated more than 1 year ago
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Created by alisha patel
over 7 years ago
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Biology unit 2
- B2.1 Cells, tissues
and organs
- plant and algal cells have
the same stuctures seen in
animal cell but include a
cell wall. Most plant cells
also have a chloroplast and
a permanent vacuole filed
with sap
- bacterial cells
contain plasmids
(small circular bits
of DNA)
- Yeast reproduces by
asexual budding -
involves a new yeast
cell growing out from
the original cell to
form a new separate
yeast organism
- when yeast cells have
plenty of oxygen they use
aerobic respiration - use
oxygen to break down the
sugars to provide energy
for the cells
- when there is no oxygen
yeast can use anaerobic
respiration - yeast cells
break down sugar in the
absence of oxygen, they
produce ethanol and co2
- yeast is a single-celled
organism - each cell has
a nucleus, cytoplasm and
a membrane surrounded
by a cell wall
- example of
specialised
cells: fat,
cone, root
hair, and
sperm cells
- dissolved
substances and
gases (oxygen)
move in and out of
cells by diffusion
- diffuision is the
net movement
of particles from
an area where
they are at a
high
concentration
to an area of
low
concentration
- the greater the
difference in
concentration,
faster the rate of
diffusion
- tissue = group
of cells with
similar structure
and function
- organs are made of
tissues, one organ may
contain several types of
tissue
- digestive system in a
mammal is an
example of a system
where substances
are exchanged with
the environment
- plant and algal cells have
the same stuctures seen in
animal cell but include a
cell wall. Most plant cells
also have a chloroplast and
a permanent vacuole filed
with sap
- B2.2
Organisms in
the
environment
- photosynthesis:
co2 + h2o ----->
glucose + o
- during photosynthesis light
energy is absorbed by
chlorophyll in the chloroplasts
of the green parts of the plant.
It is used to convert co2 and
h2o into glucose. O is released
as a by-product
- rate of photosynthesis
may be limited by
shortage of light, low
temperature and
shortage of co2
- plant and algal cells use
the soluble glucose they
produce during
photosynthesis in several
different ways: - for
respiration, to convert
into insoluble starch for
storage, to produce fats
and oils for storage, to
produce fats, protein or
cellulose for use in the
cells and cell walls
- plant and algal cells
need other materials
including nitrate ions
to make the amino
acids with make up
proteins
- factors affecting
the rate of
photosynthesis:
light levels, low
temperature and
co2 levels
- physical factors affecting
the distribution of living
organisms: temperature,
nutrients, amount of
light, avaliability of
water, avaliability
oxygen and co2
- you can get quantitative data
on the distribution of organism
in the environment using:
random sampling with
quadrats, sampling along a
transect
- photosynthesis:
co2 + h2o ----->
glucose + o
- B2.3
Enzymes
- Protein molecules are made up of long chain of amino acids
- Proteins act like a structural of tissues as hormones, antibodies and catalysts
- Catalysts work to increase the
rate of reaction without
themselves changing.
Enzymes are biological
catalysts.
- Enzymes are proteins.
The amino acids
chains are folded to
form the active site
- Enzyme activity
are affected by
temperature and
ph
- high temperature and the
wrong ph can affect the
shape of the active site of
an enzyme and stop it
working
- enzymes made in the
pancreas and the
small intestines work
best in alkaine
conditions
- bile produced by
the liver
neutralises acid
and emulsifiers
fat
- Protein molecules are made up of long chain of amino acids
- B2.4 ENERGY FROM
RESPIRATION
- aerobic respiration
involves chemical
reactions that use
oxygen and sugar and
release energy: glucose
+ oxygen -> co2 + h2o
(+energy)
- energy released
during respiration
is used to build
large molecules
from smaller
ones and allow
muscles to
contract
- body responds to
exercise: an increase in
heart rate, breathing rate
and in depth breathing,
glyogen stores in the
muscles are converted to
glucose for cellular
respiration
- act to increase the
supply of glucose and
oxygen to the muscle
and remove more
carbon dioxide
- anaerobic respiration
is respiration without
oxygen. Glucose is
incompletely broken
down to form lactic
acid
- aerobic respiration
involves chemical
reactions that use
oxygen and sugar and
release energy: glucose
+ oxygen -> co2 + h2o
(+energy)
- B2.5 CELL DIVISION
AND GROWTH
- Chromosomes
are found in
pairs
- body cells divide by
mitosis to produce more
identical cells for
growth, repair and
replacement or in
asexual reproduction
- cells in the
reproductive
organs divide
by meiosis to
form the
gametes
- in meiosis the genetic
material is copied and
then the cells divides
twice to form four
gametes, each with a
single set of
chromosomes
- embryonic stem
cells and adult
stem cells can be
made to
differentiate into
many different
types of cells
- stem cells have
the potential to
treat previously
incurable
conditions
- gregor mendel was
the first person to
suggest separtely
inherited factors
which are now
called genes
- chromosomes
are made of
large molecules
of dna
- a gene is a small
section of DNA that
codes for a particular
combination of
amino acids which
make a specific
protein
- genes can have
different forms
called alleles
- cystic fibrosis is
caused by a recessive
allele of a gene and so
must be inherited
from both parents
- Chromosomes
are found in
pairs
- B2.6 OLD AND NEW
SPECIES
- fossils are remains of
organisms from
many years ago in
the rocks
- extinction can be
caused by new
predators, new
diseases or new, more
successful competitors
- extinction can be
caused by
environmental
change over
geological time
- mass extinction
may be caused by
single castophic
events such as
volcanoes or
asteroid strikes
- new species arise
when two
populations become
isolated
- populations become
isolated when they
are seperated
geographically such
as on islands
- there are natural
cycles linked to
environmental
change when
species form when
species die out
- in a isolated
population alleles
are selected that
increase successful
breeding in the
environment
- speciation takes place
when an isolated
population becomes so
different from the
original population that
successful interbreeding
can no longer take place
- fossils are remains of
organisms from
many years ago in
the rocks
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