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Biology section 2 (COMPLETED) (A (levels of organisation (organelles…
Biology section 2 (COMPLETED)
A
levels of organisation
organelles
parts of cells
nucleus, cell membrane etc
cells
different variations with different organelles for different uses
Cilated epithel, sperm etc
tissues
made up of the same type of cell,
muscle tissue, brain tissue etc
organs
made up of the same type of tissues, to do a certain job
skin, heart etc
systems
made up of similar organs to carry out a certain job in the body
nervous system, digestive system etc
B
cell structure
animal cell
cell membrane
Cell Membrane: The basic function of the cell membrane is to protect the cell from its surroundings. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.
nucleus
Nucleus: it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes.
vacuole
lysonome
cytoplasm
Cytoplasm: Cytoplasm contains molecules such as enzymes which are responsible for breaking down waste and also aid in metabolic activity. Cytoplasm is responsible for giving a cell its shape. It helps to fill out the cell and keeps organelles in their place.
mitochondria
golgi body
endoplastic reticulum
plant cell
nucleus
.
endoplastic reticulum
golgi complex
vacuole
These membrane-bound structures are basically just enclosed compartments thatare filled with both inorganic and organic molecules, along with water to support the organelle.
cell wall
The cell wall gives the plant its actual shape. It acts as a gatekeeper, because it determines what can come in and out of the cell in order to keep the cell protected.
cytoplasm
.
mitochondria
cell mebrane
.
chloroplast
The main role of chloroplasts is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts it and stores it in the energy-storage
C
Biological molecules
chemical make up
Carbohydrates
carbon, hydrogen, oxygen
Proteins
amino acids
side chain
Carboxyl group
Carbon + oxygen
Amino Group
Nitrogen + Hydrogen
lipids
Fats and oils
glycerol, and 3 fatty acids
tests
Glucose
Benedict's or Fehling's Reagent is used to test for glucose but not for sucrose. The test involves heating the sugar with either of the chemicals and observing the colour change of blue to orange.
Starch
A chemical test for starch is to add iodine solution (red) and see if it turns blue/black in colour. It is possible to distinguish starch from other carbohydrates using this iodine solution test.
Enzymes
Role
Biological Catalysts
Speed up metabolic reactions
Affect of PH
Changes in pH may not only affect the shape of an enzyme but it may also change the shape or charge properties of the substrate so that either the substrate connot bind to the active site or it cannot undergo catalysis. In geneal enzyme have a pH optimum. However the optimum is not the same for each enzyme.
Affect of temperature
As the temperature increases, so does the rate of reaction. But very high temperatures denature enzymes.The enzyme activity gradually increases with temperature up to around 37ºC, or body temperature.
D
Movement of substances in and out of cells
diffusion
The net random movement of molecules from an area of high concentration to an area of low concentration
Oxygen in the lungs diffuses from the alveolar air space into the blood circulating around the lungs.
Osmosis
a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.
Root System Water Intake for Plants
Plant roots function as a semipermeable membrane, allowing water to infiltrate the roots.
active transport
the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
Examples of active transport include the uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants.
Cells
Turgid
ideal, if a cell is turgid it holds its structure
flacid
this means that there isn't enough solution in the cell and it looses it shape and structure
Cells bursting
if a cell has too much solution it bursts ( not plant cells)
factors effecting rate of movement
If the surface area of the cell increases, then the rate of diffusion will decrease.
An increase in temperature increases the speed at which molecules move at. An increased speed will yield faster and more even diffusion. A decrease in temperature will cause molecules to slow down. This will slow diffusion and make the spread of molecules less even.
E
Nutrition
Flowering Plants
Photosynthesis
Light energy used to convert CO2 and water into Glucose and oxygen
6CO2 + 6H2O --(light)-> C6H12O6 + 6CO2
Adaptation of the leaf
Chloroplast near surface of leaf to allow for light
large surface area
absorbs more light
Thin
Short distance for CO2 to diffuse
Network of veins
allows for the leaf to quickly transport water and minerals
Humans
Balanced diet
Carbohydrates
Provide energy
Protein
repair and protect
basic building blocks
Lipids
energy stores
Vitamins
A
Vitamin A helps form and maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin.
C
Vitamin C is needed for healing wounds, and for repairing and maintaining bones and teeth.
D
Vitamin D, along with calcium, helps build bones and keep bones strong and healthy.
Minerals
Water
Fibre
digestive system
mouth
breaks down food molecules into smaller chunks, increasing the active site for enzymes. Enzymes in the saliva also begin to break down th food
oesophogus
transport tube from mouth to stomach
moves food along, through the pulsing waves of the walls. this is peristalsis
stomach
Partial digestion of the food takes place here. The churning action of the stomach muscles physically breaks down the food. The stomach releases acids and enzymes for the chemical breakdown of food.
small intenstine
Duodenum
several enzymes added in the pancreatic juice, which is injected into the duodenum, include amylase, trypsin, liapase. Bile is also added, which is created in the liver and stored in the gaul bladder
bile is used to neutralise the stomach acid
Illeum
by this stage, food has been completely broken down and can be absorbed. It has a huge surface area due to villi and micro vili
large Intestine
rectum
foeces stored here
colon
water absorbed here
pancreas
pancreatic juice produced here
Terms
Ingestion
food is taken into the mouth
digestion
the chemical and mechanical break down of food. It converts large insoluble molecules into small soluble ones which can be absorbed
Mouth, stomach, small intestine
absorbtion
molecules diffuse into blood
small and large intestines
assimilation
molecules are used in body processes
egestion
undigested food material leaves the body via the anus
F
Respiration
The process of converting oxygen and glucose into CO2 and energy
aerobic respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O (+ Energy)
Glucose + oxygen --> Carbon dioxide + water + energy
with oxygen
anerobic respiration
C6H2O6 = 2C2H5OH + 2CO2 (+energy)
Glucose --> CO2 + Lactic acid + energy
absence of oxygen, produces less energy then aerobic
G
Gas Exchange
flowering plants
Different gasses are needed for photosynthesis and respiration
these enter the cell through the stomata
The opening and closing of the stomata is controlled by the guard cells. In light, guard cells take up water by osmosis and become turgid. Because their inner walls are rigid they are pulled apart, opening the pore. In darkness water is lost and the inner walls move together closing the pore.
CO2 and O2
adaptations of the leaves
The structure of the leaf is adapted for gas exchange. The cells in the spongy mesophyll (lower layer) are loosely packed, and covered by a thin film of water. There are tiny pores, called stomata, in the surface of the leaf. Most of these are in the lower epidermis, away from the brightest sunlight.
Humans
Ribs - Curved bones that embrace the lungs, protect them from fatal blows which may damage the lungs
Intercostal muscles - the muscles located in-between the ribs to keep the ribs in place and move the ribs when inhaling or exhaling
Diaphragm - Forms the floor of the thorax, skeletal muscle. When you exhale the diaphragm pushes up onto the lungs to help exhale and vice versa for inhaling
Trachea - This is the separated portion of the throat where air passes through into your lungs
Bronchi -The separation of the bronchus, one main branch in each lung
Bronchioles - further division of the bronchus, contains alveoli at the tips of the bronchiole where gas exchange occur
Alveoli - Air sacks in which the gas exchange of carbon dioxide and oxygen take place
Adaptations of alveoli
they give the lungs a really big surface area
they have moist, thin walls (just one cell thick)
they have a lot of tiny blood vessels called capillaries
Pleural Membrane - outer lining of the lung, its spongy and makes a slippery fluid so that there is reduced friction when rubbings against the ribs
affects of smoking
Effects of smoking on the respiratory system. The effects of tobacco smoke on the respiratory system include: irritation of the trachea (windpipe) and larynx (voice box) reduced lung function and breathlessness due to swelling and narrowing of the lung airways and excess mucus in the lung passages.
H
Transport
simple uni-cellular organisms can rely on diffusion
because substances can diffuse directly in/out the cell, so because of the short diffusion distance, rate of diffusion is quick.
They have a large surface area:volume ration, further making diffusion quicker.
need for transport systems
have a smaller SA:volume ratio
substances would have to travel a large distance to reach every single cell,
transport systems (e.g. circulatory and ventilation system) to quicken the process of getting necessary molecules in/out of the body
Plants
Phloem
Phloem is the vascular tissue responsible for the transport of sugars from source tissues
Xylem
Xylem: one of the transport systems in plants
Xylem tubes transport water and mineral salts from the roots, up the shoots to the leaves in the transpiration stream (more water is drawn up from the roots).
root hair cells
absorb water by osmosis
Plant root cells grow into long ‘hairs‘, which stick out into the soil
Each branch of a root is covered in million of microscopic hairs
the hairs give the plant a bigger SA for absorbing water from the soil
Transpiration
Transpiration is the loss of water from a plant.
Caused by: evaporation and diffusion of water from a plant’s surface (mainly happens at the leaves)
Transpiration creates a slight shortage of water in the leaf; more water is drawn up fromthe roots by xylem vessels
More water drawn up from the roots; there’s a constant transpiration stream of water through the plant
factors that effect the rate of transpiration
Light intensity
The brighter the light, the greater the transpiration rate.
The stomata closes as it gets darker, so very little water can escape.
Temperature
The warmer it gets, the faster the transpiration rate.
Water particles have more energy to evaporate and diffuse out of the stomata.
Wind speed
The higher the windspeed around the leaf, the greater the transpiration rate.
With a low wind speed, the water vapour surrounds the leaf and doesn’t move away; there’s a higher concentration of water particles outside as well as inside the leaf, meaning that diffusion is slower.
If it’s windy, the water vapour is swept away, so there’s a lower concentration of water outside leaf; diffusion is quicker.
Humidity
he drier the air around the leaf, the faster the transpiration rate.
If the air is humid, there’s a lot of water in the air, meaning diffusion is slower.
Experiment to measure transpiration:
Cut a shoot underwater (to prevent air from entering xylem) at a slant
Set the potometer up underwater (to prevent the formation of air bubbles)
Remove the apparatus from the water, but keep the end of the capillary tube inside beaker of water
Check that the apparatus is watertight and airtight, then dry the leaves
Remove capillary tube from the water, until an air bubble forms, then put it back
Record the starting position of the air bubble
se a stopwatch to record how far the bubble moves in a certain time
Humans
composition of blood
Plasma (55%)
Liquid part of blood, which is pale yellow.
it carries
Red/ White blood cells + platelets
Digested food products (e.g. glucose, amino acids) from the gut to body cells
CO2 from body cells to the lungs
Urea from the liver to the kidneys
Hormones
Heat energy
Platelets (>1%)
platelets are dead blood cells
when a breach in the vein/ capillary is detected then the platelets get sucked towards it and seal together covering the hole, allowing it to heal.
Red Blood cells (45%)
Transport O2 from the lungs to all cells in the body.
adaptations
Small, biconcave shape; large SA for absorbing and releasing oxygen
ontains haemoglobin, which contains lots of iron (and gives blood its colour); in the lungs, haemoglobin reacts with oxygen to become oxyhaemoglobin. The opposite happens in body cells, to release oxygen to cells
Don’t have a nucleus; there’s more space for haemoglobin to carry more oxygen
White Blood cells (>1%)
most important part of the immune system:
They destroy pathogens (microorganisms that cause disease) that enter the body;
phagocytes
Detects things that are ‘foreign‘ to the body, they then engulf pathogens and digest them.
They’re non-specific; they attack anything that’s not meant to be there.
Lymphocytes
When they come across a foreign antigen (every pathogen has unique molecules on its surface), the lymphocytes start producing proteins called antibodies.
Antibodies lock up on an invading pathogen, marking them out for destruction by other white blood cells.
The antibodies produced are specific, and won’t lock on any other antigen.
Antibodies then produce rapidly, flowing around the body marking similar pathogens.
Some lymphocytes stay around the blood as memory cells, after the original infection has been fought off; these can reproduce very fast if the same antigen enters the body a second time.
This is why we’re immune to most diseases.
the heart
structure
Vena cava: brings deoxygenated blood from the body
he right atrium receives it
Passes through tricuspid valve to the right ventricle
Deoxygenated blood leaves pulmonary artery
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Pulmonary vein brings oxygenated blood from lungs
Pulmonary vein brings oxygenated blood from lungs
Pulmonary vein brings oxygenated blood from lungs
Oxygenated blood leaves the aorta
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effect of exercise
As you exercise, your heart rate increases as muscles need more energy to respire: more oxygen and glucose needed in cells, and more carbon dioxide needed to be removed.
Excess carbon dioxide lowers the pH of the blood, therefore brain sends nervous impulses to the pacemaker to increase heart rate, which it does, along with the stroke value.
effect of adrenaline
When there’s stress or danger, the hormone adrenaline is released by the adrenal glands (on top of the kidneys), which readies the body for a ‘fight or flight’ response
It increases heart rate and stroke value.
arteries/ veins
arteries
Carry blood away from the heart
Carry oxygenated blood towards the body
EXCEPT the pulmonary artery
structure
Smooth lining: allows blood to flow smoother and quicker
Narrow lumen: maintains high pressure, making sure blood flows quickly to all parts of the body
Thick outer wall, thick inner layers of muscle and elastic fibre: thick to withstand high blood pressure and allows arteries to stretch under pressure
Muscle fibres contract to push blood along and keep it flowing
Endothelium
veins
Carry blood back to the heart
Carry deoxygenated blood away from the body
EXCEPT pulmonary vein
structure
Large lumen
Thin outer walls, thin layer of muscle and elastic fibre: blood returning from the body is at a much lower pressure, so the vein doesn’t have to be as strong
Endothelium
Valves: Muscles contract to push blood towards the heart, they close to prevent blood from flowing backwards
capillaries
Arteries branch into capillaries, then join up to form veins
Carries blood close to every cell in the body, to exchange substances
Supplies food and oxygen
Takes away waste, like carbon dioxide
Permeable walls: only one cell thick, so substances can easily diffuse in/out
I
Excretion
Plants
Plants need to excrete excess carbon dioxide (which is a waste product of aerobic respiration), and oxygen (which is a waste product of photosynthesis).
hese are excreted from the stomata of the leaf.
Humans
Excretion is the removal of:
Toxic materials
Waste products of metabolism
Excess substances from organisms
This is carried out by the skin (sweating), lungs and the kidneys.
The kidney
The kidneys are part of the urinary system, which removes excess water, salts and urea.
The urea is produced in the liver, from excess amino acids (amino acids contain nitrogen, which is toxic to the body if in excess).
The kidneys do this by filtering stuff like urea out of the blood under high pressure, then reabsorbing the useful things. The urea is then added to water to form urine, which travels down the ureters to collect in the bladder.
osmoregulation:
The hypothalamus detects either too much or too little water in the blood
Pituitary gland releases ADH if there’s too little water, but releases less if there’s too much water
The kidneys maintain the blood water level, or reduce it if it’s too high
If there was previously too little water, less water is lost in urine, but the opposite happens if there’s too much water
Then blood water level is able to return to normal
ADH
ADH is made in the pituitary gland (in the brain), and its role is to control water content, by increasing the permeability of kidney tubules to water.
So if there’s too little water, more ADH is released, so more water can be reabsorbed back into the blood.
If there’s too much water, less ADH is released.
The Opposite: diuretics. These increase the production of urine, as they make the collecting duct less permeable, so less water is reabsorbed into the blood.
The nephron
The kidneys contain thousands of nephrons (they’re the filtration unit of the kidneys):
Ultrafiltration: occurs in the glomerulus and bowman’s capsule
Ultrafiltration:
Blood from the renal artery flows through glomerulus (which is a bundle of capillaries at the start of the nephron)
The high pressure that’s built up squeezes the water, urea, salts and glucose outof the blood, and into the bowman’s capsule
Membranes between blood vessels in glomerulus and bowman’s capsule act like filters
Big molecules (like proteins and blood cells) aren’t squeezed out (they stay in the blood)
The filtered liquid in bowman’s capsule is called glomerular filtrate
Selective reabsorption of glucose etc. happens in the proximal convoluted tubule
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ADH affects the collecting duct
Reabsorption:
As the filtrate flows through the nephron, useful substances get selectively reabsorbed back into the body:
All glucose is reabsorbed from the proximal convoluted tubule (using active transport, against a concentration gradient)
Sufficient salt is reabsorbed (excess salt isn’t)
Sufficient water is reabsorbed from the collecting duct into the blood stream
The urinary system
Waste/excess products (including water, salts, urea) are filtered by the kidneys;
the ureter carries the urine to the bladder, which is where the urine’s stored before it leaves the body through the urethra.
Urine
Urine contains water, urea and salts, which must be removed, or they may interfere with chemical reactions, or damage cells because of increased concentration.
J
coordination and response
Sensitivity is one of the life processes (mrs gren); it is responding to the environment around.
Living things must have receptors to be able to detect the change and effectors to be able to carry out a response.
Homeostasis is the regulation of conditions inside the body.
For example osmoregulation is the control of water levels in the body.
emperature regulation also needs to take place (as body process work best at 37 degrees) it is called thermoregulation.
Effector, receptor, response
A stimulus- a change in the internal or external environment- is needed to prevoke a response.
A receptor is needed to detect a stimulus, so that it can send messages to a coordinator to
n effector is needed to carry out the response to the stimulus.
Flowering plants
Plants respond to stimuli.
water (hydro-tropism)
light (photo-tropism),
Stems experience positive photo-tropism, this means they always grow towards light.
In a place where light shines there will be fewer auxins (growth hormones) this encourages the stem to bend towards the source of light.
gravity (geo-tropism)
Roots always carry out posotive geo-tropism, towards gravity/ down.
Shoots always carry out negative geo-tropism, away from gravity/ up.
Humans
The nervous system and hormones both coordinate responses with in the body.
The nervous does this by electrical impulses so it is very fast.
Hormones do this with chemicals which travel, a little slower, at the speed of the blood stream they are travelling in.
The CNS
The CNS is the centre of the nervous system which decides a response for a stimulus.
eceptors in sense organs (eg eyes or skin) send messages through nerves to the CNS- either to you brain or spinal chord- it creates a response which it will send in electrical impulses down nerves to effectors to carry out the response.
reflex
A reflex is an automatic reaction, for example removing your hand from extreme heat. A reflex arch is the path of the reaction.
receptors pick up stimuli e.g heat;
sensory neurones carry an electrical impulse to the CNS;
A relay neuron carries the impulse through the CNS where a response is decided;
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The eye
The eye is a receptor of light, it has light receptor cells in its retina. These cells turn stimuli into electrical impulses.
In response to increased light you pupil will shrink, in dim light your pupil will dilate (grow bigger). This happens because you iris will contract to make the pupil smaller or relax to make it bigger. Radial muscles also make the pupil bigger by contracting.
To focus at different distances the lens in your eye adapts its shape:
If an object is far, ciliary muscles will relax making the suspensory ligaments tight so they pull the lens thin.
If an object is near, ciliary muscles will contract which relaxes the suspensory ligaments so that the lens is fat;
The skin
Sweating
when too hot, glands under the skin secrete sweat, this increases heat loss by evaporation.
Vasoconstriction
blood vessels by the skin shrink, this reduces the blood which runs by the surface meaning less heat can be lost to the air.
Vasodilation
blood vessels by the skin grow, this means that more blood, and so more heat, is travelling near the surface of your body, in this way heat will be lost as it is conducted by the air.
Hormones
ADH
Lack of water is detected by the hypothalamus in the brain, it causes the pituitary gland to produce Anti-diuretic hormone, or ADH. This makes the kidneys to reabsorb more water- so less is lost from the body.
Adrenaline
Produced in the adrenal glands in stressful situations. Heart rate quickens to increase the flow of blood to muscles- this means that they can respire more (as there is more oxygen available) to provide energy if you need to 'fight or flee'.
Insulin
Produced in the pancreas when there is too much glucose in the blood. It stimulates cells to convert the glucose into glycogen which is a from that can be stored. This means that you always have the right amount of glucose in your blood.
Testosterone
Produced in ovaries in girls and testicles in boys. Plays a key role in puberty, developing sex organs and inspiring hair growth.
Progesterone
Produced in the ovaries it maintains the lining ready for pregnancy, and continues to do so if the egg is fertilised.
Oestrogen
Produced in the ovaries, it is controls other hormones to regulate the menstrual cycle. It stops the production of FSH and starts the production of LH.