Biology Flashcards
(193 cards)
1
Q
Nano
A
10*-9
2
Q
Micro
A
10*-6
3
Q
Mili
A
10*-3
4
Q
Centi
A
10*-2
5
Q
Deci
A
10*-1
6
Q
Kilo
A
10*3
7
Q
Mega
A
10*6
8
Q
Gigs
A
10*9
9
Q
Eukaryotic vs procaryotic
A
Eukaryotic-plant, animal and fungi cells
Cell membrane surrounded by cell wall in plants and fungi
Contains cytoplasm, mitochondria, chlorophyll, ribosomes
DNA In nucleus- plasmids in some simple cells
Mitosis
Procaryotic-bacterial cells
Cell membrane surrounded by cell wall
Contains cytoplasm, ribosomes - no mitochondria or chloroplasts
DNA is a single molecule found free in the cytoplasm, additional DNA found in rings called plasmids
Binary fission
10
Q
Eukaryotic cytoplasm
A
Jelly like material, contains dissolved nutrients and salts and other organelles. It is where chemical reactions happen
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Q
Eukaryotic nucleus
A
Contains genetic materials including DNA, which controls the cells activities
12
Q
Eukaryotic cell membrane
A
Permeable to some substances, controls movement of substances in and out the cel
13
Q
Eukaryotic mitochondria
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Contain enzymes for respiration, where most energy is released in respiration
14
Q
Eukaryotic ribosome s
A
Tiny structures where protein synthesis or cuts
15
Q
Eukaryotic chloroplast
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(Plant) Contains green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains enzymes needed for photosynthesis
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Q
Eukaryotic cell wall
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(Plant) and bacterial cell walls provide structure and protection. Plant cell walls are made of cellulose
17
Q
Eukaryotic permanent vacuole
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(Plant) filled with cell sap to he’ll keep cell swollen
18
Q
Prokaryotic Chromosomal DNA
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(Bacterial) DNA found loose in the cytoplasm. Called chromosomal DNA not contained in nucleus
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Q
Prokaryotic plasmids
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(Bacterial) small closed circles of DNA present on their cytoplasm. Unlike chromosomal DNA, plasmid DNA plasmid DNA can move from one bacterium to another giving variation
20
Q
Prokaryotic flagella
A
(Bacteria) can have one or more flagella. These can rotate to move the bacterium
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Q
Prokaryotic cell wall
A
All prokaryotic cells have a stiff cell wall
Maintains the cells shape, protects cell interior, prevents cell from bursting when taking water
22
Q
Prokaryotic cell membrane
A
Lies underneath cell wall - plasma membrane
23
Q
Prokaryotes vs eukaryotes
A
Both have cell membrane, cytoplasm and cell wall (in some eukaryotes)
Prokaryotes have: single loop on DNA free in the cytoplasm, additional circular rings of DNA (plasmids), no nucleus
24
Q
Levels of organisation
A
Organelle - cell structure that is specialised to carry out a particular function or job
Cell-basic structural and functional unit of a living organism
Tissue-group of cells with similar structures, working together to perform a shared function
Organ- structure made up of a group of tissues working together to perform specific functions
Organ system - group of organs with related functions working together to perform body functions
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Diffusion
When particles of a substance in a liqid or gas move from a region of high concentration to a region of low concentration
Particles will move in both directions, but there will be a net movement from high to low
Will end up spread evenly throughout liquid or gas, but continue to move
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Examples of diffusion
Oxegyn moves out of plant cells by diffusion and CO2 moves into plant cells by diffusion
In the lungs- blood from body high in CO2, low in O2. CO2 diffuses from high concentration in blood to low concentration in alveolus, and O2 diffuses from high concentration in alveolus to low concentration in blood.
In the liver-urea moves from area of high concentrati0n (liver cells) to low concentration (blood vessel), and is then filtered out by the kidneys
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Ósmosis
Diffusion of water molecules form an area of high concentration to an area of low concentrati0n through a partially permeable membrane
When concentration of water is the same on either side of the membrane, particles will move but there will be no net movement
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Ósmosis in living cells
Cells contain dilute solutions of ions, sugars and amino acids. Cell membrane is partially permeable. Water moves in and out of cell through osmosis.
Plant cells-take in water through osmosis. When soul is wet, root hair cells take up water through osmosis. Leaf cells and land plants unless raining will have a tendency to lose water. Cell wall is fully permeable to all molecules and supports to cell and stops it bursting when gaining water.
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Plant cells in wate
In pure water, cell contents push against cell wall and cell becomes turgid
In concentrated solutions, cell contents lose water by osmosis. Cell becomes flaccid.
Highly concentrated solutions- cell undergoes full plamolysis as cells lose more water. When there is less water in soil, plant cells lose water by osmosis.
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Active transport
Process requires to move particles from an area of low concentrsti0n to an area of high concentration against the concentration gradient.
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Active transport in plants and animals
For plants to take up mineral ions from low concentrated soil, active transport occurs in the root hair cell.
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mitosis
type of cell division in which a diploid body cell copies itself and then divides into to identical diploid daughter cells. Daughter cells are clones of each other.
Stages:
interphase- cell spends most of its life in this phase. DNA in chromosones copies itself ready for mitosis.
Prophase- DNA in chromosones and their copies condenses to become more visible. Membrane around nucleus dissappears.
Metaphase- chromosones and their copies line up in middle of cell
Anaphase- chromosones and their copies are pulled to different ends of the cell
Cytokinesis- cell membrane pinches in and eventually divides into two daughter cells.
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Role of mitosis
increases cell numbers, repairs tissues, replaces worn out cells
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asexual reproduction
only one parent is needed
no fusion of gametes
genetic material does not mix
offspring produced are clones (genetically identical)
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cancer cells
carcinogens cause cancer by damaging DNA, causing mutations to occur. multiple mutations are revquired
cancer is the result of changes in cells that lead to uncontrolled growth and division
benign-grows slowly, usually within a membrane, can easily be removed, does not invade other parts of the body
malignant- grows quickly, invades neighbouring tissues, can spread, can detach and form secondry tumours in other parts of the body (metastasis)
cancer cells are undifferentiated - do not carry out normal function
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meiosis
cell division the produces gametes
human body cell contains 46 chromosones arranged in 23 pairs.
Human gametes are hapolids - nucleus only contains a single set of 23 unpaired chromosones
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stages of meiosis
Begins with interphase- period when cell is growing and carrying out required functions.
46 chromosones in human nucleus in 23 pairs called homologous pairs. ONe chromosone from each pair comes from the mother (maternal chromosone) and one from father
Meiosis- cell splits producing two daughter cells (gametes), chromosone number is halves (diploid to haploid so they have a single set of chromosones). Each daughter cell is genetically different.
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Asexual vs sexual reporduction
Asexual - involves one parent, offspring are genetically identical when no mutations occur.
Sexual - involves 2 parents, offspring genetically different to each other and the parents, leads to increased variation
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Sex determination
most mammles females are XX, males XY
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gene
Small section of DNA on a chromosone that code for a particular sequence of amino acids to make a specific protein. Unit of heredity and may be copied and passed onto next generation.
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Chromosones
Contained inside cell's nucleus. Long threads of DNA, made up of many genes.
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Alleles
DIfferent versions of the same gene. Eg the gene for eye colour has an allele for blue eyes and an allele for brown eyes. For any gene a person may have the same to alleles (1) or two different ones (heterozygous)
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genotype
collection of alleles that determine characteristics and can be expressed as a phenotype
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dominant allele
ALways expressed, even if only one copy is present. Represented by a capital letter. eg, allele for brown eyes is always dominant. ONly need one copy to have brown eyes.
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recessive allele
only expressed is the individual has two copies and does not have the dominant allele for that gene. represented with small letter
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homozygous
alleles are both identical for the same characteristic
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heterozygous
alleles are both different for the same characteristic
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phenotype
particular version of a characteristic seen in an individual is described as a phenotype and is determines by the genes on the chromosones that they inherited from their parents
Most phenotypic features are the result of multiple genes rather than a single gene inheritance
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genome
entire genetic material (DNA) of an organism
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Structure of DNA
DNA is a polymer made up of 2 strands forming a double helix.
Made up of 4 nucleotides, each consisting of a sugar and phosphate group with one of 4 different bases attatched to the sugar.
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complementary pairs of bases
A-T adenine with thymine
G-C guanine with cytosine
Sequence of these bases is the genetic code
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Protein synthesis
Genes carry the code for proteins.
Genetic code is read as triplets, each triplet codes for an amino acid.
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Gene mutation
change in the DNA
most mutations have no effect on the phenotype, some have a small effect, others occasionally with determine the phenotype
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genetic engineering process
Selection of desired charicteristic.
Isolation of that gene responsible for the characteristic.
INsertion of that gene into another organism.
Replication of transgenic organism.
Enzymes are used to cut out desired gene and to cut the plasmis from the bacterium. Enzymes then insert human gene into bacterium plasmid.
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restriction enzymes and ligases in genetic engineering
Restriction enzyme looks for a specific point in the DNA sequence to cut the DNA. Then it cuts, leaving a 'sticky end' which helps a new gene to attach at that point.
DNA ligase is used to attach the new DNA segment
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genetic modification diabetes
bacterial cells have been genetically modified to produce substances such as human insulin
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genetic modification crops
current genetically modified crops include those resistant to insect attack or are herbicide resistant to produce increased yields
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benefits of genetic engineering
faster and more efficient way of getting the same result as selective breeding
Improves crop yield or quality
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risks of genetic engineering
transferring the selected gene into another species may harm that new species
Not ethical to intefere with nature
GM crops are often moreexpensice
GM crops could be harmful, rg toxins from crops have been detected in some people's blood
GM crops could cause allergic reactions in people
pollen produced by plants could be toxic and harm insects
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stem cells
cells that have not undergone differentiation. A cell which has not yet become specialised - undifferentiated.
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embryonic stem cells
cells removed form an embryo.
| Can differentiate into any cell type
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adult stem cells
Some stem cells remain in the bodies of adults - adult stem cells.
Found in limited numbers in certain parts of the body (brain, eyes, blood, heart, liver, bone marrow, skin, muscle)
Can only differentiate into relates cell types, eg bone marrow cells can differentiate into blood cells and cells of the immune system but not other types of cells
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using human stem cells
have the potential to be transplanted into patients to treat medical conditions and disease. Could be used to replace cells that have been damaged or destroyed (type 1 diabetes, multiple sclerosis, spinal cord or brain injury)
EMbryonic stem cells can differentiate into a wide range of cells but are difficult to obtain and raise ethical issues.
Adult stem cells differentiate into a narrow range of cell types. Bone marrow cells will differentiate into type of blood cells and can be used in cases of blood cell cancer (leukemias) or when white blood cells have been destroyed by cancer treatment.
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Benefirs and risks of stem cell use
Great potential in treating patients with curently untreatable diseases.
NO guarantee how succesfull these therapies will be
difficult to find suitable stem cell doner.
Difficult to obtain and store a patient's embryonic stem cells. WOuld have to be collected before birth
mutations have been observed in stem cells cultured for a number of generations, some mutated cells behave like cancer cells.
Cultured stem cells could be contaminated with viruses which could be transferred to a patient
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selctive breeding
whn humans breed plants and animals for specific genetic characteristics.
Because of selctive breeding, future generations will share very similar gene pools, reduces variation. this makes it more difficult to produce new varieties in the future.
rare disases can be unknowingly selected as part of the positive trait
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Evolution
Change in th inherited characteristics of a population over time through a process of natural selection which may result in the formation of a nw species.
Evolition can occur through natural selection of variants that give rise to phenotyps best suited to their environment.
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antibiotic resistance
in a large population of bacteria, some may not b affected by antibiotics. These survive and reproduce, producing more bacteria resistant to antibiotics.
Random mutations occur in th genes of individual bacterial cells. Some mutations protect th cell from antibiotics. Bacteria with this mutation survive and reproduce with less competition from normal bacterial strains.
example of natural selection
can b caused by unnecessary use of antibiotics and not completing the full course
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variation
Can be environmental or genetic, or a combination of both.
Genetic-each sperm and egg cell contain half the genetic information needed. when the chromosomes fuse during fertilisation, a new cell is formed with a mixture of the DNA.
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enzymes
enzymes are proteins that act as biological catalysts - speed up reactions without being used up.
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mechanism of enzyme action
an enzyme works on the substrate, forming products.
An enzyme's active site and its substrate are complementary in shape. An enzyme will only work on one substrate. Enzymes and substrates collide to form enzyme-substrate complexes.
Substrates are broken down (sometimes built up), releasing products.
Enzyme is free to act again. (lock and key model)
A substrate may be broken down by the addition of water = hydrolysis reaction
Product may be formed by the removal of water = condensation reaction
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temperature and enzyme activity
As temp increases to the optimum, the kinetic energy of the enzyme and substrate increases, causing more collisions between the enzyme and substrate. Leads to increase in enzyme activity, higher rate of reaction.
As temp increases beyond the optimum temperature, the enzyme's active site becomes denatured. Can no longer form enzyme-substrate complexes, leading to a decrease in enzyme activity. Denaturation is permanent.
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pH and enzyme activity
Deviating from the optimum pH causes the enzyme's active site to become denatures and the active site loses its important shape.
It can no longer form enzyme-substrate complexes, leading to a decrease in enzyme activity.
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carbohydrases
Amylase is a carbohydrase
| digest large insoluble carbohydrates like starch (polymers) into smaller soluble carbohydrates
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proteases
digest large insoluble proteins into smaller soluble amino acids
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lipases
digest lipids (fats and oils)
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intracellular and extracellular enzymes
most enzymes work inside cells = intracellular (enzymes involved in respiration, photosynthesis) .
Produced in specialised cells in glands and tissues (salivary glands, stomach lining, pancreas, intestinal lining)
Enzymes are secreted from the cells (eg into the mouth, stomach or small intestine) where they come into contact with food molecules and begin to digest them.
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digestive enzymes commercial use
babies are not good at chewing so proteases are often used to pre-digest the proteins in baby food so that the amino acids can be absorbed without digestion.
biological washing powders contain enzymes to digest food stains.
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cellular respiration
chemical reaction which occurs in cells to release energy. Catalysed by enzymes and so the rate of respiration is sensitive to changes in temp and pH.
All living things respire and living cells respire all the time. Energy release during the reaction is used for cellular processes such as protein synthesis, active transport, cell division, muscle contraction.
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Aerobic respiration
requires oxygen
more efficient than anaerobic respiration, releases more energy. Energy is in the form of ATP.
In eukaryotic cells, aerobic respiration occurs inside mitochondria.
In prokaryotes, aerobic respiration occurs in the cytoplasm.
Glucose + oxygen = carbon dioxide + water + energy (ATP)
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Anaerobic respiration
respiration which occurs without oxygen. Releases less energy than aerobic respiration,but is important for cells that cannot obtain oxygen. This reaction takes place in the cell cytoplasm,
Glucose = lactic acid +energy (ATP)
Lactic acid is a toxic molecule so this must be removed
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during exercise
when excercising, muscle cells need more energy for contraction. this means more respiration must take place.
Breathing rate and heart rate will increase to allow more oxygen and glucose to reach the muscle cells, allowing more aerobic respiration to take place, more carbon dioxide removed from muscle cells.
Cells may not receive enough oxygen from circulation system, so they may use anaerobic respiration in addition, producing lactic acid.
after exercise breathing rate remains high, extra oxygen is needed to replenish oxygen debt to remove any lactic acid.
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nervous system
rapid communication system in animals
Made of several cells that use electrical impulses to send cellular messages.
System of nerves that connects organs and tissues
links to the central nervous system which co-ordinates the inputs from other nerves.
Neurone is one of the cells in the nervous system
nerves are made of bundles of the axons of nuerones
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central nervous system
comprises of brain and spinal cord
nerves from receptors in the sense organs bring impulses to the spinal cord which then sends them to the brain for processing
brain interprets impulses, then responds by sending an impulse via the spinal cord to the nerves which connect to the organs and tissues of the body
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nuerone
a nerve cell
transmit electircal impulses
three different types of nuerone
all contain a single nucleus in cell body and extensions of their cytoplasm allow electrical impulses to travel through them
long section of the nuerone through which the electrical impulse travels is the axon. this is surrounded by a myelin sheath. each nuerone also has a cell body containing the nucleus and dendrites which allow them to make connections to other nuerones.
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sensory nuerone
connect receptors, which detect stimuli in the environment, with the central nervous system
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relay nuerone
found withing the central nervous system. Connect sensory as well as motor nuerones, allow communication to and from the brain.
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motor nuerones
connect the central nervous system to effectors. These are parts of the body that produce a response to the electrical impulse. effectors include muscles and glands
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synapse
a synapes is a small gap between two nuerones.
Allow nuerones to transmit electrical impulses to each other.
allow multiple nuerones to connect with each other at once. these connections are made between the dendrites of different nuerones.
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how do impulses cross a synapse
electrical impulse travels along the axon of a nuerone until it reaches the end of th nuerone.
Here the impulse causes a chemical to be released into the synapse. - nuerotransmitte, it diffuses from the axon across the synapse to the nuerone on the other side.
when it reaches the surface of the dendrite, it binds to a receptor which allows the electrical impulse to be regenerated.
the new impulse then travels down the axon of the other nuerone.
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reflex arc
reflex arc is required to produce a quick reflex action. designed to protect the body from harm ,occur very rapidly. do not require processing in the brain.
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process of a reflex arc
receptor detects a stimulus
receptor generates an electrical impulse which passes to the sensory nuerone.
electrical impulse passes down the axon of the sensory nuerone to the spinal cord.
there the message crosses a synapse, using chemical nuerotransmitters, producing a impulse within a relay nuerone in the CNS.
Electrical impulse in the relay nuerone connects via another synapse to a motor nuerone.
from there, impulse progresses along the motor nuerone until it connects with an appropriate effector.
effector is a muscle which will contract
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structure of the respiratory system
respiratory system is found withtin the thorax (chest)
air enters through nose and mouth and then through the larynx (voice box). Then passes to trachea, which contains rings of cartilage which functions to ensure the airway always remains open.
trachea splits into two smaller tubes - bronchi.
once bronchus enters each lung, then split into a number of narrow tubes called bronchioles. both bronchi and bronchioles contain cartlidge
at the end of the bronchioles are air sacs called alveoli
surrounding the two lungs is the rib cage. consists of the bones and intercostal muscles between them.
diaphragm - sheet of muscle found under the lungs
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function of respiratory system
provide body with sufficient oxygen for respiration
removes carbon dioxide
gas exchange occurs between the alveoli and the blood
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air being cleaned in respiration
as air enters the body it is cleaned as it passes through the bronchi.
cell lining in bronchi produce mucus to trap any particles inhaled in the air.
small hairs (cilia) on the cells thn move the mucus up to the top of the trachea where it can be swallowed into the acid contents of the stomach in the digestive system. this destroys them
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ventilation
process of breathing in and out
allows the air in the respiratory system to be exchanged
in vertebrates, ventilation relies on movement of the ribs inside the thorax. ribs surround the lungs and are connected to each other by intercostal muscles. these muscles contract and relax to change position of rib cage. diaphragm is a sheet of muscle underneath the lungs
normal exhalation = passive exhalation
uses only the diaphragm and intercostal muscles to expell air.
active respiration - muscles of abdominal wall also contract
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inhaling
intercostal muscles contract and pull ribs up and outwards
diaphragm contracts and flattens downwards
this increases space within thoracic cavity
this lowers air pressure inside thoracid cavity compared to outside of bodt
air from outside enters the lungs via the trachea and bronchi ti equalise the pressure
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exhaling
intercostal muscles relax and pull ribs down and inwards
diaphragm relaxes and becomes domed
decreases space within thoracic cavity
reduced volume increases air pressure in thoracic cavity compared to outside the body
air from inside the lungs is forced out of the body through bronchi and trachea to equalise the pressure
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gas exchange in the lungs
gas exchange occurs when gases diffuse across the capillary and alevolar walls
oxygen is inhaled then moces along the trachea into a bronchus and then into a bronchiole, bringing it to an alveolus
oxygen diffused from the alveoulus into the blood capillary and carbon dioxide will diffuse in the opposite direction. gases move from an area of high concentration to low
oxygen binds to heamoglobin in blood which transports oxygen around the body for cells that need it.
carbon dioxide is a waste product from respiration and in transported in the blood plasma from the cells to the lungs
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body adapted for efficient gas exchange
alveoli have high surface area
thousands of alveoli in each lung
alveoli and capillary walls are only one cell thick to ensure diffusion distance in short
blood constantly flows through capillarys maintaining concentration gradients of each gas
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surface area to volume raito and gas exchange
increasing surface area to volume ratio increases the rate at which gas exchange by diffusion occurs.
large surface area presenta a large surface over which diffusion can ocrurr making it quicker.
small volume means distance that a gas has to travel is smaller
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circulatory system
consists of the heart and blood vessels. each organ has a set of blood vessels bringing blood to and from the cells of that orgab
heart - coronary
lungs - pulmonary
liver - hepatic
kidneys - renal
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arteries and veins
vessels that take blood away from the heart = arteries
vessels that return blood to the heart = veins
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vein
contains valves alon it to prevent blood flowing backwards
wide lumen
relatively thin vessel walls with less muscle and elastic tissue
carries blood at lower pressure
usually carries deoxygentated blood (except pulmonary vein)
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artery
no valves
narrow lumen
thick walls made of muscle and elastic tissue to prevent burstin
carries higher pressure blood
usually carries oxygenated blood (excpet pulmonary artery)
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capillaries
very small vessels with walls made od a single layer of cells.
allow substances to pass easily from the blood into body cells
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the heart
consists of a series of chambers with blood flow between them controlled by valves
deoxygenated blood is pumped from the right side of the heart to the lungs where it gains oxygen and loses carbon dioxide. oxygenated blood returns to the left side of the heart so it can be pumped around the body. heart muscle cells are supplied with blood via the coronary artery.
contraction of heart muscle cells is coordinated using electrical impulses which pass between different regions of the heart. these impulses are recorded with an electrocardiogram (ECG) which detects impulses using electrodes placed on the skin
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components of blood
all transported in plasma - red blood cells, white blood cells and platelets. in a healthy person, red blood cells are most numerous, white are least
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plasma
watery liquid that the cells are transported in.
contains dissolved glucose, urea and amino acids as well as carbon dioxide and some porteins like hormones and antibodies. makes up 55% the volume of blood
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red blood cells
transport oxygen
adapted shape - biconcave d
oxygen binds to haemaglobin the the cytoplasm of red blood cells.
contain no nucleus
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white blood cells
defen the body from disease
lymphocytes- produce antibodies that target antigens of bacteria and viruses to destroy them. some form memory cells
phagocytes - ingest or ingulf pathogens and digest them using enzymes
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platelets
small fragments of cells
help the blood clot
this stops blood loss and prevents microbes from entering the body
clotting occurs when a series of enzymes convert a soluble protein called fibrinogen into insoluble fibrin
this creates a mesh of fibres that traps platelets and red blood cells, forming the clot
contain no nucleus
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blood groups
the gene for the blood groups codes for a protein founf on the cell curface membrane of red blood cells - immunoglobin
gene has 3 alleles but only 2 are present in any one person
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a blood group
AA or AO, A allele is dominant to O allele - B antibodies present
can donate to A and AB
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B blood group
BB or BO, B allele is dominant to O allele - A antibodies present
can donate to B and AB
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AB blood group
AB, A and B are co dominant to both alleles are expressed
can donate to AB
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O blood group
OO, O is recessive - A and B antibodies present
can donate to any blood group
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digestive system
organ system that is invlolved in the breakdown of large insoluble molecules found in food into their soluble products and the absoprtion of these products of digestion
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process of digestive system
```
mouth
oesophagus
stomach
small intestine
large intestine
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food is moved by peristalisis - waves of muscular contraction
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enzymes in the digestive system and pH
HCl in the stomach kills bacteria and provides the correct pH for the protease enzyme
Bile and pancreatic juice contain hydrogen carbonate ions to nutralise the stomach acid when it enters the small intestine and provide the alkaline conditions needed by the enzymes present in the small intestine
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bile
made in the liver and stores in the gall bladder
relseased into the small intestine when stomach contents arrive
emulsifies lipids to increase the surface area for lipases to work on and therefore increases rate of digestion
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large molecules in food
many large molecules that need to be digested
starch, protein, lipids - large insoluble molecules cannot pass through the gut wall.
extracellular enzymes are secreated into the gut lumen to break down the large insoluble molecules in food by hydrolysis
fibre cannot be digested and absorbed in humans as the enzymes required are not present
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products of digestion
glucose, amino acids - small soluble molecules which can pass through the gut wall and are absorbed into the blood
glycerol, fatty acids - small soluble molecules which pass through the gut wall and into the ymph system before entering the bloood
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where protein is digested
stomach - by HCl and protease (pepsin) protein turns into peptide chains.
small intestine- proteases, peptide chains turn into amino acids
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where carbohydrates are digested
mouth - salivary amylase. starch turns into shorter carbohydrate chains.
stomach - HCl inactivates salivary amylase
small intestine - pacreatic amylase + carbohydrases, short chain carbohydrates turn into monosaccharides
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where fats are digested
mouth - salivary lipase - some lipids into fatty acid + monoglycerides
stomach - gastric lipase - lipids into fatty acids and monoglycerides
small intestine - bile, pancreatic + intestinal lipse - lipids into fatty acids and glycerol
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where water is digested
stomach - small amounts absorbed by stomach lining
small intestine - absorbes by small intestine lining
large intestine - most is absorbed by large intestine
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small intesitne
main site of absorption
wall of small intestine contain many villi which increase the surface area
villi contain many blood cappilaries so good blood supply to carry carry products of digestion once absorbed.
flow maintains a steep concentration gradent so diffusion is rapid and efficient
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nutrients absorbes
diffusion - higher concentration of glucose and amino acids in gut will diffuse into blood
active transport - when lower concentration of nutrients is present
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how body uses digested food
to make new macromolecules - carbohydrates, proteins, lipids
in aerobic respiraction
growth, renewal and repair - cells maintained using amino acids which combine to build different protein structures.cell membranes produces using lipids. energy is provided by glucose.
energy storage- excess glucose converted to glycogen and stored in liver and muscle cells
fatty acids are a concentrated energy store
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undigested food
indegistible components passed on to the large intestine
faeces pass through large intestine and into rectum
expelled through the anus -egestion
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excretoyu system
exretion is the removal from ogranisms of toxic materials and substances in excess of requirements. includes the liver, lungs, skin and kidneys
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the liver
not able to store protein or amino acids
any excess amino acids are broken down by the liver (deamination). Nitrogen component is converted to urea, which can be toxic if its level in the blood is too high. irea is excreted by the kidneys.
liver also breaks down haemoglobin from red blood cells. product is a yellow/green pigment called bilirubin. this is excreted with bile into the small intestine and expelled with faeces.
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the lungs in exretion
remove carbon dioxide which is a waste product
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skin
skin produces sweat, consists of sodium chloride and traces or urea dissolved in water. this ca be considered an excretory process but skin is not an excretory organ as sweating is not in response to changes in blood composition.
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kidneys
main roles involve filtration of the blood:
removal of urea
adjustment of ion content
adjustment of water content
each kidney receives blood from the aorta via a renal artery . blood is filtered to remove urea, excess water and salts. Filtered blood is then returned to the vena cava via a renal vein.
the mixture of substances is removed from the blood plasma is called urine. it passes down a ureter to the bladder where it is stored.
a sphincter muscle at the base of the bladder controls the release or urine through the urethra
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ultrafiltration
this process is achieved by microscopic structures called nephrons.
up to 4 million in a kidney.
each nephron consists of a glomerulus, renal capsule and renal tubule. cappilaries leaving the glomerulus are closely associated with the tubule.
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composition of a kidney
blood enters the kidney via a renal artery
this divides into arterioles and capillaries in the cortex.
each capillary becomes knotted to form a glomerulus which is surrounded by a Bowman's capsule.
this leads to a convoluted tubule. the proximal convoluted tubule passes down into the medulla, where it forms a loop of Henle, returning to a distal convoluted tubule in the cortex again.
the tubule joins a collecting duct, which passes down through the medulla into the pelvis of the kidney.
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how the nephron functions
walls of the cappillary in the glomerulus acts as a filter. as the blood enters the glomerulus, presuure increases.
larg structures and molecules are retained within the capillary, but smaller moleculs ( water, ions, glucose, urea) are forced out by ultrafiltration. this is filtration under pressure.
filtrate is collected by renal capsule passes into renal tubule.
as filtrate passes along the tubule, selective reabsorbtion occures into the cappilaries.
glucose is reabsorbed by diffusion and active transport.
water is reabsorbed by osmosis along with some salts by dissusion and active transport.
salts not needed and urea and uric acid continue along the tubule into a collecting duct in the medulla.
collecting duct delivers the filtrate to the pelvis in the kidney where the fluid passes into a ureter to transfer it to the bladder for storage.
urine is retained in the bladder by a sphincter muscle at its base.
when the sphincter muscle relaxes the muscle wall of the bladder contracts to expel the urine through the urethrea.
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kidneys in homeostasis
kidneys remove chemicals which may poison enzymes in cells.
all chemical reaction is cells are controlled by enzymes which are very sensitive to the conditions within the cell. kidneys control the level of salts, acids and water in the blood.
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homeostasis
maintenance of a constant internal environment
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controlling water levels
when water has been lost from the body (sweatin) kidneys respond by producing a smaller volume of more concentrated urine to conserve water in the body .
when the water levels are higher (less sweating), kidneys respond by producing a larger volume of less concentrated urine.
if the body became over hydrated, the cells would take in the surplus water by osmosis, become swollen and burst.
the regulation of how much water is excreted by the kidneys is under the control of the hormone ADH.
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negative feedback homeostasis
if a specific internal condition changes significantly from its normal levels, this change triggers a detector which sends information to an effector, which is stimulated to respond.
this response continues until the sensor detects that the level has returned to normal. the sensor then sends information back to the effector to switch it off or act in the opposite way ( negative feedback)
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temp change - negative feedback
an increase in core body temp is detected by the thermoregulatory centres and causes it to send nerve impulses to the skin, which results in effectors (arterioles and sweat glands) responding. arterioles dilate (vasodilation) and sweat glands secrete more sweat, resulting in the cooling of the skin.
as temp drops below normal, thermoregulatory centre detects this and sends nervous impulses to switch of the processes, as well as triggering other responses to increase temp - vasoconstriction and shivering
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regulation of blood glucose levels
excess blood glucose is removed by the liver and converted into the storage of carbohydrate glycogen. this mechanism is controlled by the hormone insulin.
when blood glucose levels rise, the islet cells of the pancreas detect the change and secrete insulin in response.
insulin is transported to the liver in the blood plasma, where is stimulates the liver cells to take up the glucose from the blood and convert it to glycogen.
insulin also stimulates other body cells to take up more glucose for use in respiration.
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responding to a decrease in blood glucose levels
islet cells in the pancreas are stimulated to release glucagon.
glucagon is transported to the liver in the blood plasma where it causes liver cells to convert stored glycogen into glucose to raise blood glucose levels.
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type one diabetes
inability of the pancreatic islet cells to secrete enough insulin to control blood glucose levels.
can be inherited or triggered by a viral infection which causes the body's immune system to attack the islet cells of the pancreas.
an example of an autoimmune disease
symptoms-feeling tires, thirsty, frequent urination and weight loss. may be glucose present in urine. eating a lot of carbohydrates could result in a coma.
control - carefully regulated diet and regular blood tests to monitor blood glucose levels. regular injections od insulin
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type 2 diabetes
can be inherited or a result of obesity, lack of excercise or an unhealthy diet. this can lead to insulin resistance where the body doesn't use insulin correctly
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regulation of water content - homeostasis
osmoregulation
water supplied by metabolism refers to chemical processes that occur in cells, eg product of aerobic respiration
amount of water in blood is monitored by the brain.
brain signals to the pituitary gland to increase or decrease the amount of ADH (antifiuretic hormone) it secretes
high levels of ADH cause he kidneys to reabsorb more water. so less water is excreted in urine
ADH binds to the collecting ducts of the nephrons making them more permeable to water. the water leaves the ducts and re enters the blood.
low levels of ADH cause the kidneys to reabsorb less water, so more urine is exreted.
the water is reabsorbes from the filtrate in the renal tubules of the nephrons of the kidneys, back into the blood plasma of the capillaries by osmosis
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endocrine system
uses hormones to respond to changes in the environment or in the body. made up of endocrine glands
endocrine glands produce and secrete hormones into the blood
hormones are chemicals that are carried in the blood plasma to other parts of the body so are relatively slow to act
each hormone only affects particular cells in particular organs (target structures)n and tend to have a long lasting effect
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thyroxine negative feedback
released from the thyroid gland. regulates the metabolic rate - the speed that chemical reactions take place in the body while it is at rest
release of thyroxine is controlled by TSH (thyroid stimulating hormone) which is released from the pituitary gland. this keeps the level of thyroxine in the blood within a normal range
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monitoring thyroxine
level of thyroxine in blood is monitored by the hypothalamus which is a gland close to the pituitary gland.
when thyroxine in blood is higher than is normal, the release of TSH is inhibited.
less thyroxine is released from the thyroid gland.
level of thyroxine in the blood falls to within the normal range.
when thyroxine in the blood is lower than normal, TSH is released by the pituitary gland
thyroid gland is stimulated to release more thyroxine
level of thyroxine in the blood rises to within the normal range
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role of adrenaline
released by the adrenale glands in response to scary situations. prepares the body for fight or flight
brain sends nerve impulses to adrenal glands, which are stimulated to release adreneline.
stimulates the liver to break down glycogen into glucose, increases breathing rate and heart rate, stimulates more blood flow to the muscles.
causes an increased supply of oxygen and glucose to the brain and muscles
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regulation of the menstrual cycle
FSH - produced by the pituitary gland and acts on target structures in the ovaries, stimulates an ovary to develop a follicle containing an egg and to produce estrogen
oestrogen - produced by the ovaries. stimulates the uterus lining to thicken.
LH- produced by th pituitary gland and acts on target structures in the ovarys - stimulates the mature follicle to release the egg in the middle of the cycle
progesterone - secreted by the empty follicle in the ovary, maintains the lining of the uterus during the second half of the cycle so that a fertilised egg may implant
oestorgen and progesterone inhibit the production of LH and FSH
decreasing progesterone levels cause the thickened uterus lining to break down and be discharged
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hormones in contraception
oestrogene and progesterone can prevent ovulation - inhibit FSH so prevents production of egg
progesterone also stimulates the production of thick cervical mucus so that sperm are unable to enter the uterus to fertilise an egg
oral pill - combined oestrogen and progesterone
progesterone only
not 100% effective
side effects possible (mostly due to oestrogen)
no protection from STDs
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pathogens
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pathogens cause diseases and include
viruses
bacteria
protists
fungi
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viral diseases
comprise of genetic material and a protein coat
genetic material not contained in a nucleus and lack cytoplasm
non-living
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AIDS
retrovirus - contains RNA as its genetic material and has an enzyme called transcriptase
this enzyme is only found in retroviruses and catalyses the conversion of viral RNA into DNA
can be passed from one person to another through infected body fluids that contain the virus
can enter a person across mucous membranes or if the skin of a person is broken
can be passed between people in semen or vaginal fluid or in infected blood or breast milk
can be prevented from using a condom, bottle feeding a baby. screening blood for blood transfusions
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HIV+
the virus parasitises one type of human white blood cell - lymphocyte. this causes these cells to make new HIV. HIV is released into the blood stream by destroying the lymphocyte.
lymphocytes are involved in the body's immune system so an HIV+ person may have a reduced which blood cell count so a compromised immune system, leaving them more succeptible to diseases.
no cure but there are drugs that stop reverse transcriptase from functioning - anti-retroviral drugs.
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influenza
usually spread in airborne droplets sneezed or coughed out. can also be cught through contact
prevention is covering the mouth and nose when sneezing or coughing
causes a runny nose, fever, sneezing, coughing and a sore throat
vaccines using either inactive virus or weakened virus aee available to groups ar risk
antiviral drugs are available in some circumstances
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measles
spread through direct contact - touching or through airborne mucus droplets expelled during sneezing and coughing
causes reddish blotchy rash and sensitivity to light
can be prevented by MMR vaccine which uses live weakened viruses for measles mumps and rubella
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tobacco mosaic disease
transmitted from one plant to another by direct contact ot via an insect such as an apid. virus can also remain in the soil for some itme.
stop transmission by removing infected plants and washing hands after touching an infected plant
causes leaves to have light and dark green areas and they may become wrinkled
plants infected with a milder strain of TMV acts as a vaccina and prevents a more damaging strain
can genetically modify the tobacco plant to make it resistant to the disease
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bacterial diseases
caused by bacterial pathogens
can be successfully treated with antibiotics
these either kill the bacteria or stop them reproducing, giving the body's defense system time to destroy the infection.
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salmonella
caused by salmonella bacteria
person ingests food contaminated with the bacteria
bacteria survives the low pH conditions of the stomach and reproduces in the small intestine where it causes inflammation.
causes diarrhoea vomiting and fever.
prevention - proper food preparations, washing hands, making sure frozen meat is properly defrosted
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protists
single-celled organisms that have a nucleus
plasmodium causes malaria
spread my mosquitoes infected with the protist
once a human has the protists, it enters the liver where it matures. moves into the red blood cells where it reproduces. red blood cells rupture, releasing protists which then infect more red blood cells. this reproduction can happen in regular cycles leading to the periodic fever associated with malaria.
prevention - sleeping inside mosquito nets, skin lotions with chemicals to repel mosquitoes, taking antiviral medication before going to malaria-infested areas.
interrupting the life cycle of a mosquito - adding fish to water to eat the larvae, draining areas of stagnant water
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fungal diseases
causes athelte's foot and aspergillosis - eukaryotic
aspergillosis is a group of diseases caused by the aspergillus fingus. some of these fungi produce a chemical which is a toxin and a carcinogen and can contaminate food.
fungus produces a large number of spores asexually which disperse into the air and are then breathed in.
prevention - reducing exposure to growing fungus, regulating food storage
symptoms - fever, cough, chest pain and breathlessness usually in humans with a weakened immune system
treatment - steroids and antifungal medication
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vaccinations
vaccine can contain a dead pathogen, inactive pathogen or a weakened virus unable to cause the disease.
the body defense recognises presence of non-self antigens on pathogen in the body.
WBC (lymphocytes) of the body's immune system reproduce. some of these WBCs become memory cells. many of these white blood cells produce a protein called an antibody that is specific to the antigen present.
antibody binds to the antigen on the pathogen.
these leads to antibody and antigen interacting. can lead to the destruction of the pathogen.
allows effiecient engulfin of pathogen my phagocytes leading to destruction of pathogen.
memory cells rapidly lead to the production of huge numbers of antibody and high levels of antibodies tend to destroy the pathogen before the symtoms of the disease occur - secondary immune response
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devloping new medicines
set of trials must be carried out
preclinical
clinical - testing on humans
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sequence of events for testing a drug
test on animals - make sure its safe to test on humans
tested on healthy people - to make sure it is safe and look for side effects
test on patients - make sure it works, side effects
test on many patients (double blind) - look for less common side affects, remove placebo effect
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coronary heart disease
non communicable
coronary arteries are very narrow blood vessels that supply oxygen and glucose to the hert muscles for aerobic respiration. if the branches become blocked, heart muscle cells after the blockage will not recieve oxygen and glucose and begin to carry out anaerobic respiration. if this continues, cells may die leading to reduced heart function.
blockage is usually a fatty deposit called atheroma or a blood clot
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hypertension
when someone has consistently high blood pressure
may be due to narrowing of an artery lumen due to atheroma or hardening of an artery so that it cannot expand when blood flow increases
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stroke
when part of the brain is deprived of oxygen and glucose rich blood and some brain cells may die. reason is often due to narrowin/ hardening of arteries supplying the brain tissue
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risk factors of CVD
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diet - food high in fat and high salt
little excercise
obesity
smoking
alcohol
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increasing age
gender
family history
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statins
reduce production of cholesterol, which is a component of atheroma
build up of atheroma can lead to blocked arteries
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anti-coagulants
reduce the likelihood of blood clotting and therefore blocking an artery
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anti=hypertensive drugs
can cause blood vessels to relax so their lumen diameter enlarges, reducing blood pressure
176
surgical procedures or CVD
stent - placing a mesh tube into a narrowed part of the coronary artery to increase lumen diameter so no restriction in blood flow
bypass - small section of blood vessel is removed from another part of the body and used to re-route blood around a blockage in a coronary artery
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risk factors of prostate cancer
overweight
red meat, high-fat dairy products
increasing age
family history
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breast cancer
overweight
increasing age
family history
BRCA 1 or 2 gene mutation
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colorectal cancer
overweight
low fibre diet
increasing age
family history
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nutrutuin-influences diseases
type 2 diabetes - when you eat food high in sugar, the blood glucose level will rise and the pancreas responds by releasing insulin. however on a regular basis the body, including muscle cells, become increasingly resistant to the insulin released, therefore less insluin may be produced leading to a permenantly raised blood sugar level and the relese of more glucose in the urine
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ecosystem
consists of all the living and non-living components
182
population
group of organisms of one species living and interacting in the same area at the same time
183
community
all of the populations of different species interacting with each other in an ecosystem
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habitat
place where plants and animals live
185
individual
single living organism
186
intraspecific competition
between organisms of the same species for resources such as food terrirory a mate or nesting site
187
interspecific competition
competition between organisms of different species
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population growth lag phase
the population is still very small and takes time to acclimatise to a new environment, mature and start reproducing
189
population growth log phase
no limiting factors, rapid breeding occurs resulting in significant increases in numbers
190
population growth stationary [hase
limiting factors such as food shortage or a build up of toxic materials in the environment start to have an effect, slowing down population growth, and number of deaths is equal to number of births
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population growth death phase
number of deaths becomes greater than the number of births and population numbers start to decrease
192
mutualism
close relationship between two organisms of different species where both organisms benefit
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photosynthesis
plants absorb light energy nd convert it into chemical energy stored in molecules eg carbohydrates, fats and proteins
food produced and built up in plants is known as biomass
6CO2+6H2O=C6H12O6+6O2
carbon dioxide+ water (light, chlorophyll) = glucose + oxygen
sugars are formed first then converted into starch or other carbohydrates such as celluslose for storage
