| Topic |
Notes |
| 1.
CELLS |
|
| Cell |
Basic
unit of life. Unicellular organisms like bacteria only have one cell.
Multi-cellular organisms have many cells. |
|
Organelle |
Microscopic structures in more advanced cells, which do a particular
function in that cell. eg. the nucleus, chloroplasts, mitochondria. ( NB
Bacteria cells are so simple they do not have any organelles) |
| Tissue |
Group of
cells of the same type doing a particular function. eg. the blood, xylem,
phloem |
| Organ |
Group of
tissues doing a particular function between them .eg. the heart, kidney,
leaf |
| Organ
system |
Group of
organs doing a particular function between them. eg. the circulatory system |
|
Diffusion |
Molecules and ions diffuse from regions of higher concentration to regions
of lower concentration down a gradient. Eg O2 into muscle cells. |
| Osmosis |
Osmosis
is the diffusion of water through a selectively permeable membrane. |
|
Partially permeable |
Something that selects or allows small molecules to pass through it
but not large ones. |
|
Concentration gradient |
Where
two areas have different concentrations of the same molecule. The more
different, the steeper the gradient and the faster diffusion / osmosis will
occur. |
| Active
Transport |
Movement
of molecules against the diffusion gradient, using energy from
respiration. |
|
Replication |
Exact
copying of DNA. |
| Mitosis |
Produces
2 genetically identical copies of a cell. Important in growth
and repair. |
| Meiosis |
Cell
division, which reduces (halves) the number of chromosomes. Meiosis
separates the maternal and paternal chromosomes in a cell to produce four
genetically different cells with half the usual number of
chromosomes. |
| 2.
PLANTS |
|
| Light
energy |
Photosynthesis needs light energy. It changes light energy into chemical
energy. |
| Glucose |
This is
the sugar made in photosynthesis. It is also found in fruits and in your
blood. Both plant and animal cells use glucose as a source of energy during
respiration. |
| Sucrose |
This is
a ‘double-sugar’ you use to sweeten your tea and to make jam. Sugar cane and
sugar beet store sucrose instead of starch. It is made of glucose and
fructose joined together. |
| Reducing
Sugar |
A sugar
that turns yellow / orange when heated with Benedict’s solution. Eg glucose. |
| Starch |
Most
plants store starch. They can turn starch back into glucose when they need
it for respiration. The ‘starch test’ is to add iodine solution…it should
turn blue-black. |
|
Chlorophyll |
This is
the green pigment found in plant cells that carries out photosynthesis.. |
|
Chloroplasts |
These
are tiny bodies found in palisade cells of leave. They are green because
they contain chlorophyll. |
| Carbon
dioxide |
We
excrete this gas , but plants absorb it in - they must have it for
photosynthesis. |
| Palisade
mesophyll cell |
This is
the kind of leaf mesophyll cell you need to know about. You should be able
to label a diagram of a palisade mesophyll cell. It is the site of
photosynthesis in a leaf. |
|
Variegated |
Some
leaves have white bits as well as green bits; they are called variegated
leaves. Photosynthesis does not happen in the white bits. |
| Limiting
Factor |
CO2,
temperature and light are the 3 main ones. If any are in short supply,
photosynthesis will be limited (less efficient). |
|
Transpiration |
This is
the loss of water vapour from leaves by evaporation. It is much faster when
stomata are open than when they are closed. |
|
Transpiration stream |
Water
travels up xylem vessels from the roots to the leaves in the transpiration
stream. |
| Root
hair cells |
These
are tiny hairs covering the ends of the smallest roots. They have a very
large surface area. They absorb water and mineral salts (N,P,K, Mg) from the
soil. |
| Xylem
vessels |
These
are microscopic hollow cells / tubes found in a plant's stem and ‘veins’.
They carry water and mineral salts up a plant from its roots to its leaves. |
| Phloem
tissue |
Small,
living cells in the stem and veins that transport sucrose up and down
the plant. |
| Guard
cells |
Two
guard cells surround each stoma. They can open and close the stoma. |
| Stomata |
Stomata
are tiny holes in the epidermis (skin) of a leaf. They are usually found on
the undersides of leaves. Each stoma is surrounded by two guard cells. |
| Auxin |
This is
a plant hormone that causes cells to divide and grow. |
| Hormone |
This is
a chemical messenger (in animals, hormones travel in the blood – and are
made by ductless glands).. |
| Tropism |
This is
a growth movement of part of a plant towards or away from a stimulus such as
light, gravity or moisture |
|
Phototropism |
A
response to (+) or away (-) from light. |
|
Geotropism |
A
response to or away from gravity. |
| 3.
BREATHING |
|
|
Epiglottis |
This is
a little flap on the back of the throat; it closes the top of the trachea
when we swallow so that food does not go down ‘the wrong way’. |
| Trachea |
This is
the proper name for the windpipe. It has ‘C-shaped’ rings of cartilage
support. |
| Bronchus |
The
trachea divides into two tubes called bronchi. |
|
Bronchioles |
Each
bronchus divides into many smaller tubes called bronchioles. These can
expand. |
| Goblet
cells |
These
are cells in the lining of the trachea and bronchi, which make mucus. |
| Gaseous
exchange |
This
means oxygen getting into the blood and carbon dioxide going out by
diffusion. |
|
Intercostal muscles |
Intercostal means 'between the ribs'. One set of intercostal muscles makes
the ribcage bigger (inspiration) and another set makes it smaller
(expiration). |
| Mucus |
This is
a white slimy protein, which traps germs and bits of dirt which get breathed
in. This stops the delicate tissues of the lung from being damaged. |
| Cilia |
These
are tiny hairs which beat continuously to move the mucus up the bronchi and
trachea. |
| Alveoli |
These
are the tiny air sacs in the lungs – they have a huge surface area, but are
only one cell thick. All gas exchange takes place here.. |
| Large
surface area |
Added
together, the alveoli have an enormous surface area (70 square metres)
through which gaseous exchange can happen. |
|
Bronchitis |
Caused
by the effects of tar in cigarette smoke. Paralyses cilia and causes
over-production of mucus in the trachea and bronchioles. |
|
Emphysema |
Break
down of the alveoli – less surface area to absorb gases like oxygen. |
| Lung
Cancer |
Caused
by cancer-causing chemicals (carcinogens) in tar. Tumours form. |
| Carbon
Monoxide |
Toxic
gas in cigarette smoke. Binds irreversibly with blood haemoglobin, meaning
less oxygen can be carried. |
| Nicotine |
Addictive component of cigarette smoke. Cause platelets to clump together in
blood, leading to strokes and heart attacks. |
| 4.
TRANSPORT |
|
| Red
Blood Cells |
These
blood cells contain haemoglobin and carry oxygen. |
|
Haemoglobin |
This is
the protein in red blood cells, which turns into oxyhaemoglobin in
the lungs. |
| White
Blood Cells |
Phagocytes engulf bacteria and form ‘pus’; B-lymphocytes produce antibodies
that attach to foreign antigens; T-lymphocytes reject foreign cells like
transplanted tissues. |
|
Platelets |
These
are fragments of cells, which help to clot our blood when we cut
ourselves. |
| Plasma |
This is
the liquid part of blood. It contains nutrients, hormones,
antibodies, fibrinogen, and waste products like urea and dissolved CO2. |
|
Transport |
This is
the main job of the blood. Substances are carried around the body in our
blood. |
| Artery |
This is
a thick walled muscular, elastic blood vessel. It carries blood away
from the heart at high pressure to other parts of the body. |
| Vein |
This is
a thin walled, valved blood vessel, which carries blood back to the
heart. |
|
Capillary |
This is
a very narrow one-cell walled blood vessel, which carries blood through our
tissues. Exchanges between cell and blood occur at the capillaries. |
| 5.
DIGESTION |
|
| Enzymes |
These
are the biological catalysts, which are needed to break down your food, and
carry out all chemical reactions in cells. Eg. Catalase, protease, amylase,
lipase |
| Saliva |
Saliva
contains an enzyme called salivary amylase which digests starch to maltose
sugar, and mucus which makes the food in your mouth slippery and easy to
swallow. |
| Amylase |
Enzyme
that digests starch into maltose. |
| Protease |
Enzyme
that digests proteins to amino acids. |
| Lipase |
Enzyme
that digests fats to fatty acids and glycerol. |
|
Denaturing |
The
enzyme structure is destroyed by heating above 50°C |
| Optimum |
The
‘best’ conditions for an enzyme eg. Pepsin works best in acid conditions of
stomach. |
|
Peristalsis |
The
rhythmic contractions of circular and longitudinal muscles that moves food
along the gut. |
| Stomach |
The part
of the gut where proteins are first digested (by protease). HCl kills
microbes. |
| Duodenum |
This is
the first part of the small intestine. Bile secreted by the liver makes the
contents of the duodenum alkaline and helps to emulsify (increase surface
area) the fats and oils in our food. |
| Ileum |
This is
the longest part of the small intestine. Here food is completely digested.
The products of digestion are absorbed by villi, which have a large
surface area to speed up absorption. |
| Villi |
Tiny
finger-like projections that increase surface area for absorption of small
molecules. |
| Liver |
Heaviest
organ of the body, responsible for processing all the food absorbed by
digestion. |
| Colon |
This is
the large intestine; it is where all the water in our food and drink
is absorbed into the blood. |
|
Absorption |
This is
the diffusion of useful substances into our blood and lymphatic systems. |
|
Assimilation |
This is
when the absorbed food becomes a part of your body. It is either used to
provide energy, or it is used to help growth and repair of tissues. The
liver is the main organ. |
| 6.
RESPIRATION |
|
|
Mitochondria |
Small
structures (‘organelles’) inside active cells. They carry out aerobic
respiration. |
| Aerobic |
Requires
oxygen to respire. This sort of respiration releases the most ATP energy. |
|
Anaerobic |
Respires
in the absence of oxygen. Plants / yeast produce ethanol, animals produce
lactate (lactic acid). |
|
Metabolism |
All the
chemical processes in our cells. Your ‘basal metabolic rate’ or BMR is a
measure of how active you are.. |
| Lactic
acid (lactate) |
A toxic
chemical produced in anaerobic respiration of animals, it causes cramp. |
| Energy |
Released (not ‘produced’) in respiration & required for other
activities. |
| ATP |
A high
energy chemical made during respiration and used in cells as an energy
store. |
| 7.
NERVOUS SYSTEM |
|
| CNS |
The
Central Nervous System consists of the brain and spinal cord. |
| Neurone |
This is
a nerve cell. It carries an electrical impulse when it is stimulated. |
| Sensory |
Sensory
neurones carry impulses from sense organs into the CNS. |
| Motor |
Motor
neurones carry impulses out of the CNS to effector organs. |
|
Intermediate neurones |
These
nerve cells carry messages around the CNS. |
| Sense
organ |
For
example, the eye, ear, taste buds, skin, nose. |
| Receptor |
Structure in the skin that detects a stimulus. Eg ‘touch receptor’, ‘rod or
cone cells in retina’ |
| Effector
|
A muscle
or gland which has an effect when it is stimulated by a motor neurone
impulse. |
| Reflex
arc |
A nerve
pathway which produces an automatic response. The brain is not involved. |
| Reflex |
A rapid,
automatic, life-saving response that was present at birth. Eg. Blink-reflex. |
| Stimulus |
For
example, light, heat, sound, gravity, smell, taste, or temperature. |
| Response |
This is
the effect produced by an effector organ, for example you salivate when you
taste something. |
|
Co-ordination |
This
means producing a sensible response when you are stimulated. For example,
when you taste something nice you salivate, you don't scratch your toe. |
| 8.
EYES |
|
| Cornea |
Curved
transparent part at the front of the eye that refracts (bends) most light. |
| Iris |
Coloured
part of the eye. Muscles can open or close the pupil to let more or less
light in. |
|
Accommodation |
The
‘fine – focussing’ of the eye carried out by the lens. |
| Retina |
Contains
light sensitive cells. Rods are sensitive to dim light, cones work best in
bright light and can detect colour (R,G,B) |
| Blind
Spot |
Point
where the optic nerve leaves the back of the eye. |
| 9.
HORMONES |
|
| Hormone |
Chemical
released from a ductless gland. Hormones travel in the blood. |
| ADH |
Anti
Diuretic Hormone - released from pituitary gland to control water loss from
collecting ducts of kidney. |
| Insulin |
Released
from ‘ islet cells ‘ of the pancreas. Insulin lowers blood glucose by
helping liver cells to store glucose as glycogen. |
| Glucagon |
Hormone
that raises blood glucose ( as does ‘Adrenalin’) in the opposite way to
insulin. |
| Diabetic |
Person
who cannot produce enough insulin. Glucose is detected in urine. Leads to
coma and death unless treated with genetically engineered insulin. |
| FSH |
Follicle
Stimulating Hormone – released from pituitary gland, causing an egg to
develop in the female ovary. |
|
Oestrogen |
Released
from ovary as egg / follicle is developing. Causes uterus lining to thicken
in preparation for a possible egg implantation. Inhibits FSH action. |
| LH |
Lutenising Hormone. Released from pituitary gland around ‘day 14’ of cycle.
Causes the egg to be released from follicle. |
|
Progesterone |
Last of
the four hormones to be released in the cycle. Produced in ovary from the
remains of the follicle. Keeps the uterus lining well supplied with blood.
If no egg-implantation (‘pregnancy’), Progesterone levels fall and lining is
lost (menstruation). |
| ‘The
Pill’ |
Contains
oestrogen ( to prevent FSH working – hence no follicle can develop). |
| 10.
KIDNEYS |
|
| Nephron |
The
functioning unit of a kidney. There are a million nephrons per kidney. |
| Cortex |
The
outer layer of a kidney, containing glomeruli and Bowman’s Capsules |
| Medulla |
The
middle layer of a kidney, containing collecting ducts and loops of henle. |
|
Glomerulus (-i) |
A knot
of capillaries where the blood is filtered out. |
| Bowman’s
Capsule |
Surround
the glomerulus and collects the filtrate. |
| First
Coiled Tubule |
Where
all glucose is reabsorbed back into blood. Also 95% of water and salts
are re-absorbed here. |
| Loop of
Henle |
Regulates water balance. Desert animals have longer Loops of Henle. |
|
Collecting Duct |
Place
where ADH (see above), acts to make final adjustments to water balance. More
ADH = more water conserved by the body. |
|
Osmoregulation |
The
constant process of maintaining steady levels of water in the blood. |
|
Homeostasis |
The
constant process of maintaining steady levels of sugar, water, salt,
temperature etc. in the body. Osmoregulation is an example of homeostasis. |
| 11.
GENETICS |
|
| DNA |
De-oxy-ribo-Nucleic-Acid.
Long double-helix molecule responsible for the division of cells and having
the code to make proteins for the cell. |
|
Chromosomes |
Lengths
of DNA found in the nucleus of cells. Human cells have 23 pairs of
chromosomes |
| Genes |
Shorter
lengths of DNA arranged along a chromosome. Each gene codes for a
characteristic protein of the body. |
| Allele |
Each
parent contributes one allele, making PAIRS of alleles in the offspring. So
an allele is one-half of a gene. |
| Dominant |
The
allele codes for the correct protein. Only one allele is needed (out of two)
for this. |
|
Recessive |
The
allele has had a mutation at some point and no longer codes for the original
protein. BOTH alleles must be recessive in order for the offspring to show
the result. |
|
Homozygous |
Both
alleles are the same – either both dominant or both recessive. |
|
Heterozygous |
Gene
consists of one of each type (one dominant, one recessive) |
| Genotype |
The
combination of alleles ‘homozygous dominant’, ‘heterozygous’ etc. |
|
Phenotype |
The
physical expression of the genotype – i.e. what the creature looks like. |
| Gamete |
Contains
HALF the chromosome number of the parent |
| HGP |
Human
Genome Project – set up to identify every one of the 20 000 genes in a human
cell. |
| Clone |
An exact
genetic copy of another cell – a result of mitosis. |
| Stem
Cell |
A
privileged cell from an embryo with the potential to be ‘cloned’ into any
organ or tissue of the body. |
| Genetic
Engineering |
The
placing of a gene into a ‘foreign’ host DNA, so that the host produces a
useful product of that gene eg. Human insulin gene inserted into
bacteria. |
| 12.
MAN’S IMPACT |
|
|
Eutrophication |
Over-growth of algae in ponds and lakes, caused by nitrate fertilisers
washing off from fields. When the algae finally die, oxygen levels of the
water fall dangerously low. |
| Acid
Rain |
Caused
by emissions of NO2 and SO2 from fossil fuel
combustion, which dissolve in rain water to form acids |
| ‘Green
house effect’ |
Carbon
dioxide from combustion of fossil fuels traps long – wave radiation in the
atmosphere. May result in changed weather patterns, melting of ice caps etc. |
| ‘Ozone
Hole’ |
Caused
by release of CFC’s (chloro-fluoro-carbons) from refrigerators and air-con
systems. |
|
Alternative Fuel |
A more
sustainable form of energy release that causes less pollution. Eg solar
panels, wind turbines, bio-gas, hydro-electric, nuclear. |
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