2. structure and functions in living organisms Flashcards
to do: gas exchange (paper 2- 2.40-> 2.45B) and co ordination and response
fill in the blanks
cells are separated from their surrounding environment by ____ ________, within this, there is _________, within this in eukaryotic cells the following organelles are present: _______, __________ (singular mitochondrion), _________
plant cells contain the following additional structures: ____ ____, _________, permanent _______
cell membrane
cytoplasm
nucleus
mitochondria
ribosomes
cell wall
chloroplasts
vacuole
what are the different levels of organisation in organisms
- organelles
- cells
- tissues
- organs
- organ systems
what is an organelle
a component within a cell that carries out a specific task
what is a cell
basic functional and structural units in a living organism
what is a tissue
a group of cells of similar structure working together to perform a particular function
what is an organ
made from a group of different tissues working together to perform a particular function
what are organ systems
made from a group of organs with related functions, working together to perform body functions within the organism
describe the function of the nucleus
controls the cell, contains DNA
describe the function of the mitochondria
where aerobic respiration takes place, energy is released
describe the function of the ribosomes
site of protein synthesis
describe the function of cytoplasm
where cells chemical reactions takes place
describe the function of the cell membrane
controls what goes in and out of the cell
describe the function of the cell wall
made of cellulose (plants), supports the cell
describe the function of chloroplasts
contains a green pigment (chlorophyll), absorbs light for photosynthesis (making glucose)
describe the function of the vacuole
contains cell sap, help keeps the cells shape
the main structures in animal cells are:
nucleus, cell membrane, mitochondria, ribosomes, cytoplasm
in addition to the structures found in animal cells, what else do plant cells contain?
cell wall (made of cellulose), permanent vacuole (filled with cell sap, pushes the cytoplasm against the cell wall, keeping the cell turgid), and chloroplasts (site of photosynthesis)
what are specialised cells
- have developed certain characteristics that allow them to perform particular functions
- these differences are controlled by genes in the nucleus
what happens when a cell differentiates
it develops a structure and composition of a subcellular structures which enables it to carry out a certain function
what are undifferentiated cells called, and what are they mainly involved in
- adult stem cells
- replacing and repairing cells (such as blood or skin cells)
what are some examples of specialised cells
- ciliated cell
- nerve cell
- red blood cell
- root hair cell
- palisade mesophyll cell
what are the different types of stem cells
- embryonic stem cell
- adult stem cell
- meristem cells
what is a stem cell
an undifferentiated cell of an organism that is capable of dividing an unlimited amount of times and can differentiate into others
why are embryonic stem cells important
as they help to form all of the different tissues and organs needed during development to form a whole new individual (are totipotent)
what is the role of adult stem cells
to replace cells lost through damage or to produce new cells for growth
what are meristem cells
- in plants
- are unspecialised cells that can differentiate into the cells needed by the plant in regions where growth is occurring
what are the advantages of using stem cells in medicine
- medical benefits in therapeutic cloning to heal diseases and chronic illnesses
- potential in discovering treatments and cures for diseases such as Parkinson’s disease and cancer
- ability to test potential drugs and medicine without the use of animals or human simulation
- reduced risk of rejection as patient’s own cells can be used
what are the disadvantages of using stem cells in medicine
- ethical issues surrounding the use of embryonic stem cells involving the destruction of human embryos
- uncertainties regarding long-term effects
- rejection by patient’s body as certain stem cells are obtained from embryos instead of their own cells
- difficulty in controlling differentiation of pre-specialised cells into desired cell
what chemical elements are present in carbohydrates?
carbon, hydrogen, oxygen
(CHO)
what chemical elements are present in protein?
carbon, hydrogen, oxygen, nitrogen
(CHON)
what chemical elements are present in lipids (fats and oils)?
carbon, hydrogen, oxygen
(CHO)
how do carbohydrates get broken down?
-> name the molecule enzyme and product
starch -> amylase -> maltose -> maltase -> glucose
how do lipids get broken down?
-> name the molecule enzyme and product
large lipid droplets -> bile -> small lipid droplets -> lipase -> fatty acids and glycerol
how do proteins get broken down?
-> name the molecule enzyme and product
protein -> pepsin/ protease -> peptides -> trypsin (protease) -> amino acids
PRACTICAL
describe the test for reducing sugars:
- add benedicts solution to food sample
- place in 80C water bath for 5 mins
- colour change = blue -> brick red
PRACTICAL
describe the test for starch:
-add iodine solution to food sample
- colour change = orange -> blue black
PRACTICAL
describe the test for protein:
- add biuret solution to food sample
- colour change = blue -> purple
PRACTICAL
describe the test for lipids:
- emulsion test- add ethanol to food sample, shake
- add water, shake
- colour change = colourless -> cloudy white emulsion
what are some safety hazards for each food sample test?
- iodine is an irritant to the eyes, so wear goggles
- same with copper (II) sulfate in biuret solution
- ethanol is highly flammable, so keep away from Bunsen burner
definition of an enzyme
a biological catalyst that speeds up the rate of metabolic reactions without being changed or used up in the process
fill in the blanks: (mechanics of enzyme reaction)
the shape of the ________ is specific / ________ to the ______ ____
substrate
complementary
active site
describe the effect of temperature on enzymes:
- as temperature increases, so does the rate of metabolic reaction, as there is more kinetic energy and therefore more enzyme-substrate collisions occur
- the optimum temperature is 40C- this is when the most collisions happen
- too high temp= too much kinetic energy, active site changes shape, enzymes denature
- remember too low temp does not denature enzymes- instead, low rate of reaction due to the lack of kinetic energy
practical: investigate how enzyme activity can be affected by changes in temperature
- add starch solution to a test tube and heat to a set temperature using a beaker of water + bunsen burner
- add iodine to spotting tile
- use a syringe to add amylase to the starch solution, mix well
- every minute transfer a drop of the solution to the iodine (should turn blue/black)
- repeat until it stops turning blue/ black
- record the time taken
- repeat using a range of temperatures
what is the optimum pH for enzymes?
7 (but some are produced in acidic conditions like the stomach have opH as 2, and some are made in alkaline conditions like duodenum have a higher opH like 8/9)
what happens if the pH is too high or too low for an enzyme
at extreme pH (furthest from optimum) enzymes are completely denatured, so no activity
at optimum pH the rate of reaction is very high
moving away from the optimum pH results in a gradual loss of activity as the active sit becomes distorted
define diffusion
movement of molecules from a high to low concentration down a concentration gradient
define osmosis
net movement of water from a high water potential to a low water potential across a partially permeable membrane
define active transport
movement of molecules against a concentration gradient from a low to high concentration gradient. uses energy
where does diffusion occur?
in the lungs, alveoli, villi
where does osmosis occur?
large intestines, kidney
where does active transport occur?
root hair cells (have lots of mitochondria, so can respire, so have energy for active transport)
explain how the root hair cell takes up nitrate ions from the soil. what would happen if you added air?
by active transport- where the nitrate ions move from a low to high concentration against the concentration gradient, by using energy from respiration
by adding air, it increases oxygen, so increases respiration, so increases energy which is needed to complete active transport
fill in the blanks:
diffusion helps living organisms to:
-obtain many of their __________
-get rid of many of their _____ products
-carry out ___ exchange for __________
requirements
waste
gas, respiration
what would happen if an animal cell is placed in distilled water?
- cell has lower water potential than the solution
- so water moves into the cell via osmosis (high-low)
- cell will swell, may lyse (burst)
what would happen if an animal cell is placed in a strong sugar/salt solution?
- cell has higher water potential than solution
- so water moves out of the cell via osmosis (high-low)
- cell becomes crenated (shrivelled up)
what would happen if a plant cell is placed in a strong sugar/salt solution?
- cell has a higher water potential than the solution
- net movement of water out (loses water via osmosis (high-low))
- vacuole gets smaller and cell membrane shrivels away from cell wall
- becomes flaccid or plasmolysed
what would happen if a plant cell is placed in distilled water?
- cell has a lower water potential than the solution
- net movement of water in (gains water via osmosis (high-low))
- vacuole gets bigger, pushing the cell membrane against the cell wall
- becomes turgid
give one feature of the cell wall which allows the cell to become turgid
its elastic, strong and fully permeable
how does surface area affect the rate of diffusion?
greater the surface area to volume ratio is, the greater the rate of diffusion is
how does distance affect the rate of diffusion?
the smaller the distance, the faster rate of diffusion is (that’s why capillaries and alveoli have walls that are only 1 cell thick)
how does temperature affect the rate of diffusion?
the higher the temperature, the more kinetic energy there is, so the molecules are able to move/ spread faster- therefore increased diffusion rate
how does concentration gradient affect the rate of diffusion?
greater the difference in concentration, the faster the rate of diffusion is
what type of reaction is photosynthesis?
endothermic (chemical reaction that takes in energy from the surroundings- i.e. energy from sunlight is transferred to the chloroplasts)
describe the process of photosynthesis:
energy from sunlight is absorbed by chlorophyll
green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
at the same time, oxygen is made and released as a waste product
what is the word equation for photosynthesis?
carbon dioxide + water -> glucose + oxygen
what is the symbol equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
what are the limiting factors of photosynthesis?
temperature, light intensity, carbon dioxide concentration
how does temperature affect the rate of photosynthesis?
as temperature increases the number of collisions increases, therefore the rate of photosynthesis increases. however, at high temperatures, enzymes are denatured.
how does light intensity affect the rate of photosynthesis?
the more light a plant receives, the faster the rate of photosynthesis up to a certain point
how does co2 concentration affect the rate of photosynthesis?
the more co2 that is present, the faster the reaction occurs
what is the function of the waxy cuticle?
- reduces water loss by evaporation by waterproofing the leaves (protective layer on top)
- barrier to disease causing microorganisms
- contains few stomata- reduce water loss
what is the function of the upper epidermis?
thin and transparent- allows sunlight to reach the palisade mesophyll for photosynthesis
what is the function of the palisade mesophyll?
- column shaped, thin and arranged close together (uniformed)
- contains many chloroplasts and densely packed so that as much light energy can be absorbed as possible for efficient photosynthesis
what is the function of the vascular bundle?
- contains xylem and phloem to transport substances to and from the leaf
- xylem - transports water and mineral salts from the root to leaves (one way)
- phloem - transports sucrose and amino acids around the plant
what is the function of the spongy mesophyll?
contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases (mainly co2)
what is the function of the lower epidermis?
- acts as a protective layer, contains more stomata compared to upper epidermis to regulate loss of water and site of gaseous exchange into and out of the cell (less exposed to light- so less evaporation of H2O)
what is the function of the stomata?
- regulates water loss (transpiration)
- site of gaseous exchange in the leaf
what is the function of the guard cells?
controls the opening and closing of the stomata
what are some adaptations of the leaf?
- leaf = large SA - increases surface area for the diffusion of co2 and absorption of light for photosynthesis
- thin - allows co2 to diffuse to palisade mesophyll quickly
why do plants need mineral ions? which ones do they need most?
for growth
magneisum and nitrates
how do plants obtain mineral ions?
actively absorbed from the soil by root hair cells
why do plants need magnesium? what is its deficiency?
- to make chlorophyll (function)
- causes yellowing of the leaves (deficiency)
why do plants need nitrates? what is its deficiency?
- to make amino acids (function)
- causes stunted growth and yellowing of the leaves (deficiency)
what does a balanced diet consist of?
carbohydrates, proteins, lipids, dietary fibre, vitamins, minerals, water
what are the sources and functions of carbohydrates?
function- source of energy
source- bread, cereals, pasta, rice, potatoes
what are the sources and functions of protein?
function- growth and repair
source- meat, fish, eggs, pulses, nuts
what are the sources and functions of lipids?
function- insulation and energy storage
sources- butter, oil, nuts
what are the sources and functions of dietary fibre?
function- provides bulk (roughage) for the intestine to push food through
sources- vegetables, whole grains
what are the sources and functions of water?
function- needed for chemical reactions to take place in cells
sources- water, juice, milk, fruits and vegetables
what are the sources and functions of calcium?
function- needed for strong teeth and bones and involved in the clotting of blood
deficiency can lead to osteoporosis later in life
sources- milk, cheese, eggs
what are the sources and functions of vitamin D?
function- helps the body to absorb calcium, and so required for strong teeth and bones
sources- oily fish, dairy products, also made naturally by the body in sunlight
what are the sources and functions of vitamin C?
function- forms and essential part of collagen protein, which makes up skin, hair, gums and bones
deficiency can cause scurvy
sources- citrus fruit, strawberries, green vegetables
what are the sources and functions of vitamin A?
function- needed to make the pigment in the retina for vision
sources- meat, liver, dairy, leafy green vegetables like spinach, eggs
what are the sources and functions of iron?
function- needed to make haemoglobin (the pigment in red blood cells that transports oxygen)
sources- red meat, liver, leady green vegetables like spinach
what affects energy requirements?
activity levels, age, pregnancy, sex
how does age affect energy requirements?
energy young people need increases towards adulthood as this energy is needed for growth-so need a higher proportion of protein in their diet. energy needs of adults decreases as they age
how does activity levels affect energy requirements?
the more active, the more energy required for movement as the muscles are contracting more and respiring faster
how does pregnancy affect energy requirements?
increases as energy is needed to support the growth of the developing foetus, as well as the larger mass that the mother needs to carry around. extra calcium and iron are also needed in the diet to help build the bones, teeth and blood of the foetus
how does breastfeeding affect energy requirements?
increases and extra calcium is still needed to make high quality breast milk
how does sex affect energy requirements?
male average energy requirements tend to be more than females as they have a larger proportion of muscle mass
how is food moved through the gut?
by peristalsis (which is muscle contraction)
what is the alimentary canal?
channel/ passage where food flows through the body, starting at the mouth and ending at the anus (the digestive system)
describe the structure and function of the mouth/ salivary glands
where mechanical digestion takes place- teeth chew food to break it down into smaller pieces and increase SA:V
amylase enzymes in saliva start digesting starch into maltose
describe the structure and function of the oesophagus
tube that connects the mouth to the stomach
where peristalsis occurs (muscle contraction that pushes food down)
describe the structure and function of the stomach
where food is mechanically digested by churning actions, while protease breaks down protein, hydrochloric acid is present to kill bacteria in food and provide the optimum pH for protease to work
describe the structure and function of the small intestine
first section is called the duodenum which is where all food groups finish being digested
pH is slightly alkaline (around 8-9)
second section is the ileum which is where absorption of digested food molecules takes place into the blood (apart from water), it is long and lined with villi to increase SA
describe the structure and function of the large intestine
water is absorbed, remaining material in the colon produces faeces which is stored in the rectum and removed through the anus
describe the structure and function of the pancreas
makes enzymes for the small intestine (amylase, protease and lipase), secretes the enzymes in an alkaline fluid into the duodenum for digestion
describe the structure and function of the liver
produces bile
amino acids that are not used to make proteins are broken down here (deamination) which produces urea
describe the structure and function of the gall bladder
stored bile
what is ingestion?
the taking in of substances, e.g. food and drink, into the body through the mouth
what is mechanical digestion?
the breakdown of food into smaller pieces without chemical change to the food molecules- e.g. chewing, churning, emulsification- increases SA for enzymes to work on
what is absorption?
the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
what is assimilation?
the movement of digested food molecules into the cells of the body were they are used, becoming part of the cells
what is egestion?
the passing out of food that has not been digested of absorbed (as faeces) through the anus
what is the purpose of digestion?
to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream
what is the role of bile?
neutralising stomach acid
emulsifying lipids
what are the adaptation of the villus in the small intestine?
- large surface area- lots of villi and microvilli
- short diffusion distance- walls are 1 cell thick
- high concentration gradient- lots of capillaries
- lacteal absorbs fat
how is the small intestine adapted for absorption?
very long and has a highly folded surface with millions of villi (increases surface area)
peristalsis also occurs
why do organisms need energy (ATP)?
-for muscle contraction (movement)
-maintain body temp
-metabolic reactions (making new molecules)
compare aerobic and anaerobic respiration (oxygen, glucose breakdown, products, energy released)
AEROBIC
-oxygen needed
-glucose breakdown = complete
-products = CO2+H2O
-energy released = a lot
ANAEROBIC
-oxygen not needed
-glucose breakdown = incomplete
-products = animal cells- lactic acid, yeast- carbon dioxide and ethanol
-energy released = a little
what is the word equation for aerobic respiration
glucose + oxygen -> carbon dioxide + water
what is the symbol equation for aerobic respiration
C6H12O6 + 6O2 -> 6CO2 + 6H2O
what is the word equation for anaerobic respiration in animals
glucose -> lactic acid
what is the word equation for anaerobic respiration in plants and fungi
glucose -> ethanol + carbon dioxide
what are the biological consequences to smoking? what chemicals cause this?
coronary heart disease
tar, nicotine, carbon monoxide
how does tar affect the body due to smoking
- tar is a carcinogen which is linked to increased chances of cancerous cells developing in lungs
- contributes to COPD
causes chronic bronchitis (destroys cilia and mucus builds up which blocks bronchioles and leads to infections- smoker’s cough is the attempt to move this mucus) - causes emphysema (develops as a result of frequent infection, phagocytes break down alveoli so they become less elastic and cannot stretch, so burst, which reduces SA for gas exchange, which causes patients to become breathless and wheezy)
how does nicotine affect the body due to smoking
- narrows blood vessels leading to increased blood pressure, also increases heart rate- both of which can cause blood clots to form leading to heart attack or stroke
- also is addictive
how does carbon monoxide affect the body due to smoking
- binds irreversibly to haemoglobin reducing the capacity of blood to carry oxygen
- this puts more strain on the breathing system as breathing frequency and depth need to increase in order to get the same amount of oxygen in the blood, which increases risk of coronary heart disease and strokes
explain how bronchitis develops
- chemicals in tobacco smoke destroy cilia, reducing their number, at the same time mucus production will increase; this is in response to the smoke
- the mucus cannot be moved out of the airways quickly and so builds up
- bronchitis is a disease resulting from the build-up of infected mucus in the
bronchi and bronchioles
explain emphysema
alveoli are damaged and become deformed, this reduces their surface area for gas exchange so less oxygen diffuses into the blood
how is water absorbed by root hair cells
via osmosis
how are root hair cells adapted for efficient uptake of water (by osmosis) and mineral ions (a.t)
- large surface area for maximum water and mineral absorption
- lots of mitochondria, therefore lots of energy produced for active transport
what is the route of water through a plant?
water moves by osmosis into the root hair cells (from high to low water potential) and into the xylem which is a hollow water tube made of cells and has walls strengthened by lignin, which transports the water to the mesophyll cells in the leaves
what is transpiration
the evaporation of water from the leaves (stomata) of plants
what is the function of transpiration
-transport mineral ions
-provides water to keep cells turgid
-provides water to leaf cells for photosynthesis
-keeps the leaves cool
how does temperature affect transpiration?
increases
as high temp = more kinetic energy, therefore more molecules evaporate faster
how does light intensity affect transpiration?
increases
as more sunlight = more photosynthesis, therefore more water used as a reactant and more stomata open, allowing water to be lost
how does wind speed affect transpiration?
increases
as more wind = more water molecules moved away, which maintains the concentration gradient of water, so more water moves out by evaporation
how does humidity affect transpiration?
decreases
high humidity reduces concentration gradient, so less water is lost
what are the excretory products of the lungs
carbon dioxide and water
what are the excretory products of the kidneys
water, mineral ions and urea
what are the excretory products of skin
water and mineral ions
what are the two functions of the kidney
- regulate water content of the blood (which is vital for maintaining blood pressure)
- excrete the toxic waste products of metabolism (such as urea and substances in excess of requirements such as salts)
what is the nephron
- a tube in the kidney
- there are thousands/millions of them
- network of capillaries are wrapped all round it
- made up of several sections- bowmans capsule, proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct
what processes happen in the kidney (in order)
- ultrafiltration
- selective reabsorption of glucose
- reabsorption of water and salts
describe what happens at the glomerulus
- capillaries get narrower as they get further into the glomerulus (which increases the pressure)
- this causes smaller molecules that are being carried in the blood to be forced out of the capillaries and into the bowman’s capsule (forms the filtrate)
- known as ultrafiltration
- small substances include glucose, water, urea, salts
- big substances that cant pass through include proteins, RBC, WBC and platelets
where is water reabsorbed at in the kidney
loop of henle and collecting duct
where are salts reabsorbed at in the kidney
loop of henle
where is glucose reabsorbed at in the kidney
proximal convoluted tubul (PCT)
where is urea reabsorbed at in the kidney
its not!
what happens at the bowmans capsule
ultrafiltration
describe what happens at the proximal convoluted tubule (PCT)
- selective reabsorption of glucose
- contains lots of mitochondria for active transport of glucose
- some water and salts also diffuse out via osmosis and A.T
describe what happens at the loop of henle
- reabsorbs water
- is a salty environment (called the medulla) which helps water to move out of the nephron and back into the blood by osmosis
- salts are also reabsorbed by diffusion
describe what the kidney would be like for someone with diabetes
- people with diabetes have high glucose levels in their blood, which means that not all the glucose filtered out can be reabsorbed, so ends up in the urine
- this is why one of the first tests a doctor may do to check if someone is diabetic is to test their urine for the presence of glucose
what is the composition of urine
urea, mineral ions, water
what would happen to your urine if you drink lots of fluids
the more fluids drunk, the more water will be removed from the body and so a large quantity of pale yellow, dilute urine will be produced
what would happen to your urine in high temperature or exercise
the higher the temperature, the more water is lots in sweat and so less will appear in the urine, meaning a smaller quantity of dark yellow, concentrated urine will be produced
PRACTICAL
describe the method of testing a leaf for starch
- boil leaf in water (with water bath or bunsen burner) to soften leaf and denature enzymes in plant cells
- boil leaf in ethanol (removes chlorophyll)
- drop iodine onto the leaf
- if turns blue black it contains starch-> therefore the area contains chloroplasts and has been photosynthesising
PRACTICAL
plan an experiment investigating how light affects the rate of photosynthesis of elodea (pondweed)
c- light intensity
o- pondweed
r- 10x and find and average
m- rate of photosynthesis at varying distances e.g. 10,20,30,40,50,60,70,80,90,100cm
s-species of pondweed, no. of leaves in pondweed, length of pondweed, temperature
PRACTICAL
how do you find out how much energy is in a certain food? (6marks)
- weigh banana chip
- use the same mass/ volume of water. measure temp
- light banana chip on fire
- heat water using banana chip
- burn until it has completely burnt
- measure change in water temp
- energy content = 4.2xmass of waterxtemp change/ mass of crisp
- repeat to make reliable
what 3 measurements do you need to take before you burn the food when investigating the amount of energy in different foods practical
mass of food, starting temp of water, volume of water
PRACTICAL
how do you use a potometer to estimate the rate of transpiration
-cut stem at slant underwater
-check for air leaks
-record where air bubble is starting from
-record after a certain amount of time where the air bubble finishes
-repeat the experiment and reset the air bubble
how would you calculate the volume of water lost in the potometer practical (equation)
pi r squared x distance moved by air bubble
what are the different levels of organisation in organisms
organelles, cells, tissues, organs and organ systems
what is an organelle
a component within a cell that carries out a specific task e.g. a nucleus, mitochondria, ribosomes
what is a cell
basic functional and structural unit in a living organism, specialised to carry out particular function
what is a tissue
a group of cells of similar structure working together to perform a particular function
what is an organ
made from a group of different tissues working together to perform a particular function
what is an organ system
made from a group of organs with related functions, working together to perform body functions within the organism
difference between unicellular and multicellular organisms
Uni- made from one cell, whereas multi made up of collections of cells
what happens during inhalation
- diaphragm contracts and flattens
- intercostal muscles contract
- ribs move up and out
- this increases volume of the chest cavity (thorax)
- which decreases air pressure
- so air is drawn in
what happens during exhalation
- diaphragm relaxes and moves upwards
- intercostal muscles relax
- ribs move down and in
- this decreases the volume of the chest cavity (thorax)
- which increases air pressure
- so air is forced out
how is the alveoli adapted for gas exchange?
- lots of alveoli- large surface area to volume ratio
- walls are 1 cell thick - short diffusion distance
- lots of capillaries - maintains a high concentration gradient
key features of an artery
- thick muscular walls
- narrow lumen
- carries oxygenated blood away from the heart at high pressure
- blood flows through at fast speed
how is the artery adapted to its function
- has a thick muscular wall- can withstand high pressure of blood
- narrow lumen helps to maintain high pressure
key features of a vein
- thin walls
- large lumen
- contain valves
- carries deoxygenated blood towards the heart at low pressure
- blood flows through at a low speed
how is a vein adapted to its function
- large lumen reduces resistance to blood flow under low pressure
- valves prevent the backflow of blood
key features of a capillary
- walls are one cell thick
- carries both oxygenated and deoxygenated blood
- carries blood slowly at low pressure
- have ‘leaky’ walls
how is a capillary adapted to its function
- walls are one cell thick - short diffusion distance
- ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells
why does frequency of breathing increase when exercising?
muscles are contracting and aerobically respiring more, so need more oxygen delivered to them (and carbon dioxide removed)
‘after exercise has finished, the breathing rate remains elevated for a period of time.’ why?
- lactic acid has built up in muscles- needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
- can only be removed by combining with oxygen (repaying the oxygen debt)
- the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt needs to be repaid
fill in the gaps!
the hydrogen carbonate indicator is ______ in atmospheric CO2 levels
in high CO2 levels it absorbs the CO2 and becomes _____
in low CO2 levels it loses CO2 and becomes ______
orange
yellow
purple
what do all plants need to grow
WOW!
Warmth - to provide optimal conditions for enzymes
Oxygen - for aerobic respiration
Water/ Moisture - to disrupt the seed coat and swell
what are the two functions of the urinary system
- to filter waste products from the blood and expel it from the body as urine
- to control the water levels of the body (osmoregulation)
describe the structure of the urinary system
- consists of two kidneys (found at the back of the abdomen) joined to the bladder by two tubes called the ureters
- another tube (urethra) carries urine from the bladder to outside the body
- each kidney also connects to: the renal artery (comes from aorta and delivers oxygenated blood) and the renal vein (delivers deoxygenated blood from kidney to vena cava)
what is the kidney
two bean-shaped organs that filter the blood
what is the ureter
tube connecting the kidney to the bladder
what is the bladder
organ that stores urine (excess water, salts and urea) as it is produced by the kidney
what is the urethra
tube that connects the bladder to the exterior; where urine is released
difference between ureter and urethra
- ureTER = connects kidney to bladder
- ureTHRA = connects bladder to exterior; where urine is released
how does glucose get reabsorbed in the nephron
- after the glomerular filtrate enters the Bowman’s Capsule, glucose gets reabsorbed at the proximal convoluted tubule
- takes place by active transport
- nephron is adapted for this by having many mitochondria
why can reabsorption of glucose take place only in the PCT
as the gates that facilitate the active transport of glucose ae only found in the proximal convoluted tubule
what is the composition of the glomerular filtrate
glucose, water, urea, salts
true or false, water is also reabsorbed from the collecting duct (as well as the loop of henle) in different amounts depending on how much water the body needs at the time
true
what hormone is the water content of blood controlled by
ADH
is the water content of the blood is too high then ____ water is reabsorbed
less
if the water content of the blood is too low then ___ water is reabsorbed
more
where is the change in water level of the blood detected by
the hypothalamus
what happens when the hypothalamus detects a change to the water level of the blood
sends a signal to the pituitary gland in the brain, which constantly releases a hormone called ADH
how much ADH released depends on…
how much water the kidneys need to reabsorb from the filtrate
what does ADH do
affect the permeability of the tubules to water
if the water content of the blood is too high:
- pituitary gland releases less ADH
- which leads to less water being reabsorbed in the collecting ducts by osmosis
- so the collecting ducts become less permeable to water
- so the kidneys produce a large volume of dilute urine
if the water content of the blood is too low:
- pituitary gland releases more ADH
- which leads to more water being reabsorbed in the collecting ducts of the kidney by osmosis
- so the collecting ducts become more permeable to water
- so the kidneys produce a small amount of concentrated urine
what is the source, role and effect of the hormone ADH
- pituitary gland
- controlling the water content of the blood
- increases the permeability of the collecting ducts in the kidneys to water, increasing the reabsorption of water back into the blood
what is the source, role and effect of the hormone FSH
- pituitary gland
- causes the ovary to develop a mature egg cell
- stimulates the development of the egg cells in the ovary and the release of oestrogen
what is the source, role and effect of the hormone LH
- pituitary gland
- causes ovary to release a mature egg cell
- stimulates the release of an egg cell from the ovary (ovulation) and the release of progesterone
what happens when you are too hot (cooling mechanisms in humans)
- vasodilation of skin capillaries
- sweating
- flattening of hairs (pilo-relaxation)
what happens when you are too cold (warming mechanisms in humans)
- vasoconstriction of skin capillaries
- shivering
- erection of hairs (pilo-erection)
describe vasodilation
- hypothalamus recognises that you are hot
- sends electrical impulses down a motor neurone to the muscle in the arterioles
- arteriole muscle relaxes, causes it to dilate, increases blood flow
- more blood flow to surface capillaries
- more heat loss by radiation
describe vasoconstriction
- hypothalamus recognises that you are cold
- sends electrical impulses down a motor neurone to the muscle in the arterioles
- arteriole muscle contracts, constricting the blood flow
- less blood flows to the surface capillaries
- less heat loss by radiation
describe sweating as a cooling mechanism in humans
- sweat is secreted by sweat glands
- this cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
describe the flattening of hairs as a cooling mechanism in humans
- the hair erector muscles in the skin relax, causing hairs to lie flat
- this stops them from forming an insulating layer by trapping air and allows air to circulate over the skin
- allows heat to leave by radiation
describe shivering as a warming mechanism in humans
- is a reflex action in response to a decrease in core body temperature
- muscles contract in a rapid and regular manner
- the exothermic metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature
describe the erection of hairs as a warming mechanism in humans
- the hair erector muscles in the skin contract, causing hairs to stand on end
- this forms an insulating layer over the skins surface by trapping air between the hairs (causes a convection current)
- stops heat from being lost by radiation
what is the core body temperature of humans, and what change can be fatal
- 37C
- change of more than 2C
what detects temperature change in the body
- temperature receptors (also known as thermoreceptors)
- which are in the part of the brain called the thermoregulatory centre
- located in the skin and hypothalamus
describe the practical for how enzyme activity can be affected by changes in pH
- add iodine to spotting tile
- add amylase to test tube
- add buffer solution to test tube
- add another test tube of starch solution to amylase and buffer solution- start the stopwatch whilst mixing using pipette
- every 10 seconds transfer droplet of solution to iodine
- should turn blue black
- repeat until stops turning blue black
- record the time
- repeat with buffers of different pH values
what are the components of blood
red blood cells, white blood cells, platelets and plasma
describe red blood cells
- biconcave disc shape for large surface area to volume ratio
- no nucleus for room for haemoglobin (which binds to oxygen to form oxyhaemoglobin)
- transports oxygen
describe white blood cells
- part of the immune sytem
- large cells containing a large nucleus
- two types: phagocytes, lymphocytes
what are phagocytes
- type of white blood cell
- larger cells with a multi-lobed nucleus
- engulf and digest pathogens
what are lymphocytes
- type of white blood cell
- large cell with a very large nucleus
- make and release antibodies which bind to and destroy pathogens
what are platelets
- cell fragments
- help clot blood and form scabs
what is plasma
- straw coloured liquid that transports blood cells and many other substances including:
- waste products (CO2 and urea)
- dissolved nutrients (glucose, amino acids)
- hormones
- heat energy
how are red blood cells specialised for their job
- no nucleus - more room for haemoglobin so more oxygen can be transported
- biconcave disc - increases SA:V and decreases distance, so increases diffusion.
- contain haemoglobin - a protein that combines with oxygen to form oxyhaemoglobin- transports oxygen to respiring cells
what is the body’s immune system response to disease
- pathogen enters the blood stream and multiplies
- release of toxins and infection of body cells causes symptoms in the patient
- phagocytes recognise there is a pathogen and engulf and digest (non-specific response)
- lymphocyte recognises its antigens and produces specific antibodies
- lymphocyte also clones itself
- antibodies support the destruction of pathogens by binding to them
- phagocytes engulf and digest the destroyed pathogens
what is the difference between antigen and antibody
- antigen is a molecule found on the surface of a cell
- antibody is a protein made by lymphocytes that is complementary to an antigen, and when attached, clumps them together and signals the cells they are on for destruction
what do platelets do
clot the blood, which prevents blood loss and the entry of microorganisms
what are vaccines
- used to induce immunity
- contains harmless versions of a pathogen
how do vaccines work
- once in the blood stream, the antigens contained within trigger an immune response
- lymphocytes recognise the antigens and produce antibodies specific to it
- memory cells are produced from the lymphocytes
- memory cells and antibodies subsequently remain circulating in the blood stream
what do vaccinations enable
- future antibody production to the pathogen to occur sooner, faster and in greater quantity
- due to memory cells
what side of the heart does oxygenated blood enter
left side
what does the left ventricle have that means it can pump blood at high pressure around the body compared to the right
a thicker muscle wall
what side of the heart does deoxygenated blood enter
right side
what type of blood vessel pumps blood towards the heart
veins
what type of blood vessel pumps blood away from the heart
arteries
what are the purpose of valves
prevent backflow of blood that is travelling at a low pressure
what does the right side of the heart do
pump deoxygenated blood to the lungs
what does the left side of the heart do
pump oxygenated blood to the body
what is the left and right side of the heart separated by
the septum
what is the function of the circulatory system
to transport substances around the body
name the valve between right atrium and right ventricle
tricuspid valve
name the valve between the left atrium and left ventricle
bicuspid valve
name of valve between right ventricle and pulmonary artery
semi lunar valve
name of valve between left ventricle and aorta
semi lunar valve
describe the pathway of deoxygenated blood
- deoxygenated blood from the body flows through the vena cava into the right atrium
- atrium contracts and blood is forced through the tricuspid valve into the right ventricle
- ventricle contracts and blood is pushed through the semi lunar valve into the pulmonary artery
- the blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place at low pressure
describe the pathway of oxygenated blood
- oxygenated blood returns via the pulmonary vein to the left atrium
- atrium contracts and forces blood through the bicuspid valve into the left ventricle
- ventricle contracts and blood is forced through the semi lunar valve and out through the aorta
- left ventricle contains thicker walls so produces high pressure for blood to travel around the body
how does heart rate change during exercise
- increases- more oxygen needed for the respiring working muscles
- production of adrenaline also increases it too
what factors increase the risk of coronary heart disease
- obesity
- high blood pressure
- high cholesterol
- smoking
how does obesity cause CHD
- carrying extra weight puts a strain on the heart
- this can lead to type 2 diabetes which further damages the blood vessels
how does high blood pressure cause CHD
- increases the force of blood against the artery walls and consequently leads to damage of the vessels
how does high cholesterol lead to CHD
- speeds up the build up of fatty plaques in the arteries leading to blockages
how does smoking cause CHD
- chemicals in smoke cause an increase in plaque build up and increase in blood pressure
- carbon monoxide also reduces the oxygen carrying capacity of the RBC
what are the three types of blood vessels
- arteries
- veins
- capilaries
what are the key features of an artery
- carry blood at high pressure away from the heart
- carry oxygenated blood (except the pulmonary artery)
- have thick muscular walls containing elastic fibres
- have a narrow lumen
- blood flows through at a fast speed
how is the structure of an artery adapted to its function
- thick muscular walls containing elastic fibres withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through
- narrow lumen also helps to maintain high pressure
what are the key features of a vein
- carry blood at low pressure towards the heart
- carry deoxygenated blood (other than the pulmonary vein)
- have thin walls
- have a large lumen
- contain valves
- blood flows through at a slow speed
how is the structure of a vein adapted to its function
- a large lumen reduces resistance to blood flow under low pressure
- valves prevent the backflow of blood as it is under low pressure
what are the key features of a capillary
- carry blood at low pressure within tissues
- carry both oxygenated and deoxygenated blood
- have walls that are one cell thick
- have ‘leaky’ walls
- speed of blood flow is slow
how is the structure of a capillary adapted to its function
- capillaries have walls that are one cell thick (short diffusion distance) so substances can easily diffuse in and out of them
- the ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells
what takes blood to and away from the heart
towards:
- vena cava
- pulmonary vein
away:
- aorta
- pulmonary artery
what takes blood to and away from the lung
towards:
- pulmonary artery
away:
- pulmonary vein
what takes blood to and away from the kidney
towards:
- renal artery
away:
- renal vein
what are the names of the artery(s) and vein(s) involving the liver
- hepatic vein
- hepatic artery
- hepatic portal vein (leads to stomach and intestines)
what are carbon dioxide and oxygen in plants and how are they released
- wasted products of metabolism- respiration and photosynthesis
- released from the stomata
why can simple, unicellular organisms rely on diffusion for movement of substances in and out of the cell
as they have a large surface area to volume ratio
why do multicellular organisms need a transport system
as they are composed of multiple cell layers, making the distance from the surface to the centre too long for diffusion alone
what is the xylem
- makes up the transport system of vascular plants, along with the phloem
- is a hollow tube of dead cells
- walls are thickened with lignin, which provides a route for the column of water to move through by transpiration
what is the role of the xylem
to transport water and mineral ions from the roots to other parts of the plant
what is the role of the phloem
- to transport sucrose and amino acids between the leaves and other parts of the plant
- is formed from living cells forming a tube with small holes through which substances can move
what does the thorax (chest cavity) consist of
- the ribs
- intercostal muscles
- diaphragm
- trachea
- bronchi
- bronchioles
- alveoli
- pleural membranes
describe the ribs
bone structure that protects internal organs such as the lungs
describe the intercostal muscles
muscles between the ribs which control their movement, causing inhalation and exhalation
describe the diaphragm
sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation
describe the trachea
windpipe that connects the mouth and nose to the lungs
describe the bronchi
large tubes branching off the trachea with one bronchus for each lung
describe the bronchioles
bronchi split to form small tubes (bronchioles) in lungs connected to alveoli
describe the alveoli
tiny air sacs where gas exchange takes place
describe the pleural cavity
the fluid filled space between the pleural membranes which reduces friction and allows the lungs to move freely
describe what happens during inhalation
- diaphragm contracts and flattens
- intercostal muscles contract to pull the ribs up and out, increasing the volume of the thorax
- this decreases air pressure inside the lungs relative to outside the body, so air is drawn in
describe what happens during exhalation
- diaphragm relaxes and moves upwards back into its domed shape
- intercostal muscles relax so the ribs drop down and inwards, decreasing the volume of the thorax
- this increases air pressure inside the lungs relative to outside the body, so air is forced out
how is the alveoli adapted for gas exchange (large SA)
- many alveoli- large surface area- increases rate of diffusion
how is the alveoli adapted for gas exchange (distance)
- walls of the alveoli and capillary are one cell thick- short diffusion distance- speeds up diffusion
how is the alveoli adapted for gas exchange (conc. gradient)
- each alveolus surrounded by a network of capillaries- good blood supply- steep concentration gradient for CO2 and O2- increases rate of diffusion
describe a reflex arc
- receptor detects …
- impulse moves along sensory neurone to central nervous system (relay neurone)
- neurotransmitters diffuse across synapse
- motor neurone to effector
- effector carries out response (muscle contraction)
what is the central nervous system
consists of the brain and spinal cord, coordinates all responses (movement and reflexes)
name the 3 different types of neurones and their purpose
- sensory neurones - carry impulses to central nervous system
- relay neurones - decreases response time between sensory and motor
- motor neurones - carry neurones away from central nervous system, to the effector
what is an effector
usually a muscle, carries out a response
what is a synapse
small gap between 2 neurones
describe what happens at the synapse
- release of neurotransmitters
- diffuse across the gap (synapse)
- transmitting the impulse between neurones
advantages of reflexes
- fast
- no brain involvement (involuntary)
- so less damage/ harm
how does the eye adjust to looking at a distant object
- suspensory ligaments contract
- ciliary muscles relax
- lens becomes long and thin (less convex shape)
- less refraction of light
how does the eye adjust to looking at a close object
- suspensory ligaments relax
- ciliary muscles contract
- lens becomes thicker with a more convex shape
- more refraction of light
how does the eye adjust to a bright light
- circular muscles contract
- radial muscles relax
- iris becomes wider
- pupil constricts, letting less light in
how does the eye adjust to dim/ no light
- radial muscles contract
- circular muscles relax
- iris becomes narrower
- pupil dilates to let more light in
what happens if blood glucose is too high
- pancreas produces the hormone insulin
- insulin stimulates cells to take glucose in from the bloodstream (particularly from the liver and muscles cells)
- in liver and muscle cells excess glucose is converted into glycogen for storage
what happens if blood glucose is too low
- pancreas produces the hormone glucagon
- stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the bloodstream, increases the blood glucose levels.
how does the body respond when it is cold
- piloerection - hair stands on end (warm air becomes trapped underneath the hairs, creating a convection current that acts as a warm insulating layer)
- vasoconstriction - arterioles supplying the capillaries near the surface of the skin constrict (get narrower) so less blood flows near the surface of the skin so less heat is lost by radiation
- less sweat released so less heat lost by evaporation
how does the body respond when it is hot
- pilorelaxation - hairs lie flat and so an insulating layer of air isn’t formed so more heat is lost
- vasodilation - arterioles supplying the capillaries near the surface of the skin dilate, more blood flows near the surface of the skin, so more heat is lost by radiation
- more sweat is released - when sweat evaporates, heat energy is taken away from the skin as the evaporation of water requires energy
how does fight or flight reflex occur in the body
- blood diverted from intestine to muscles
- increased heart rate means more blood to muscles
- breathing rate increases/deeper breathing
- rate of respiration increases as more oxygen is delivered to muscle cells
- pupils dilate - increased visual sensitivity
- glycogen converted to glucose
what is homeostasis
the maintenance of a constant internal environment
what is the source, role and effect of the hormone adrenaline
- released by adrenal gland
- increases heart and breathing rate for fight or flight response
what is the source, role and effect of the hormone insulin
- released by pancreas
- causes liver and muscle cells to take up glucose and convert it into glycogen for storage
what is the source, role and effect of the hormone testosterone
- released by testes
- causes development of male secondary sexual characteristics
what is a tropism
directional growth responses made by plants in response to light or gravity (stimuli)
what is the different between a positive and negative response (tropism)
- positive - growth towards the stimulus
- negative - growth away from the stimulus
what are the words for responses to light and responses to gravity
- light- phototropism
- gravity- geotropism
what would the responses for a plant growing towards light and upwards be
- positive phototropic response- towards light
- negative geotropic response- away from gravity
what are auxins
- plant growth regulators
- they coordinate and control directional growth responses (phototropism and geotropism)
- made in the tips of shoots
- cause cell elongation
what happens when light is shone predominantly on one side of a plant
- auxin produced in the tip concentrates on the shaded side, making the cells elongate and grow faster than the cells on the sunny side
- unequal growth causes the shoot to bend and grow in the direction of light
what are the adaptations of neurones
- long -> travel over large distances -> allows quick and accurate communication and response
- myelin sheath acts as an electrical insulator -> increases speed of transmission
- projections and divisions (dendrites) -> communication to other neurones/increase surface area
- gaps -> move quicker (nodes) -> instead of gradually moving through, can jump from one node to the next
- lots of mitochondria in nerve cells -> provide energy for synthesis of neurotransmitters (pass messages across synapse)
