Organisation (seneca) Flashcards
Human skin and the waxy covering of some plants are examples of which kind of tissue?
Epidermal tissue
The stomach contains the following tissues:
- Muscular tissue
- Epithelial tissue
- Glandular tissue
Glandular tissue produces …
digestive juices that break down the stomach’s contents.
Organs are …
groups of distinct tissues that work together to perform a specific function
The digestive system is an organ system made up of the following organs:
- Large intestine
- Glands
- Liver
- Stomach
- Small intestine
The large intestine, which ————————————-. This allows it to produce …
- absorbs water molecules from the remaining undigested food
- faeces
Glands (e.g. ————————-), produce digestive enzymes.
pancreas and salivary glands
Glands (e.g. pancreas and salivary glands), which …
produce digestive enzymes.
The liver, which …
produces bile.
The stomach, which …
digests food.
The small intestine, which …
digests food and absorbs soluble (can be dissolved) food molecules.
An ——— is the highest level of organisation in a multicellular organism, consisting of several organ systems.
organism
what is a Organism?
The highest level of organisation consisting of several organ systems.
what is a Organ
system?
Groups of organs that work together to perform a particular role.
what is a Organ?
Groups of distinct tissues that work together to perform a specific function.
what is a Cell?
The fundamental unit of all living organisms.
what is a Tissue?
Groups of similar cells that work together to perform a similar function.
Enzymes are often called …
biological catalysts.
To catalyse (speed up) a reaction, the reacting chemical (substrate) must bind …
to the enzyme’s active site.
The active site will …
only fit specific substrates.
Which part of an enzyme do substrates bind to?
active site
what is an enzymes?
An enzyme is a protein that increases the rate of a reaction.
Enzymes are also known as biological catalysts.
Describe the lock and key mechanism of enzyme action.
The active site is like a lock and the substrate is like a key.
In the same way, there is usually only one enzyme for every substrate (or one key for each lock).
What does ‘denatured’ mean?
An enzyme is denatured if its structure is altered and it can no longer catalyse a reaction.
How do you calculate the rate of reaction from a graph of mass of product against reaction time?
The rate of reaction is equal to the gradient of the graph, which shows mass of the product plotted against the reaction time.
What type of molecule is an enzyme?
protein
There is usually ———- enzyme for every substrate.
one
Enzymes have an optimum…
pH (measure of acidity).
If the pH changes away from the optimum pH, the enzyme activity …
decreases.
If the pH is too low or too high, the enzyme is …
denatured and will not function.
Increasing the temperature of a working enzyme initially …
increases the reacting activity.
Enzymes have an optimum 1. Once this temperature is reached, the activity 2.
- temperature
- decreases.
Past a certain temperature, the active site …
changes shape, and the enzyme is denatured (loses its catalytic activity).
reaction rate (with time and mass) =
change in mass / change in time
Digestive enzymes are made by …
specialised cells in the glands and the gut lining
The digestive enzymes catalyse (speed up) the …
breaking down of large and insoluble molecules of food into smaller, soluble molecules that can be absorbed into the bloodstream.
Digested molecules can be used to construct new …
carbohydrates, proteins and lipids in the body.
Some glucose produced by digestion is used for …
respiration
The 3 main digestive enzymes are:
- Amylase
- Protease
- Lipase
Bile is an …
alkaline substance produced in the liver and stored in the gallbladder.
Enzymes in the small intestine operate best in ——— conditions.
alkaline
Bile breaks up fats into————, through a process called ————.
tiny droplets
emulsification
Bile breaks up fats into tiny droplets, through a process called emulsification.
The tiny droplets have a higher surface area than the 1.
This increases the rate of the 2. reactions that break fats down.
- original fat drop
- lipase-catalysed
Bile ——— acid from the stomach to stop these enzymes becoming denatured (lose their activity).
neutralises
Where is bile stored?
Gall bladder
Without bile to neutralise acid in the stomach, what would enzymes become?
Denatured
Amylase breaks down starch into its …
constituent simple sugars (predominantly maltose).
Starch →
Maltose (+ other sugars).
The sites of action of amylase are:
The small intestine.
The mouth.
Add ———- and heat for about two minutes to test for sugar.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
Benedict’s reagent
Proteases are produced in the:
Pancreas.
Stomach.
Small intestine
The sites of action of proteases are the:
Small intestine.
Stomach.
Proteases are digestive enzymes that can break down proteins into …
amino acids.
Protein →
Amino acids.
Lipase is produced in the:
Small intestine.
Pancreas.
Lipid →
glycerol + fatty acids
Lipase breaks down lipids into a …
molecule called glycerol and fatty acids.
Add ————- to test for starch.
It will turn blue-black if starch is present.
iodine solution
Add iodine solution to test for —-.
It will turn blue-black if starch is present.
starch
Add iodine solution to test for starch.
It will turn ———- if starch is present.
blue-black
Add ————- and heat for about two minutes to test for sugar.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
Benedict’s reagent
Add Benedict’s reagent and ————— to test for sugar.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
heat for about two minutes
Add Benedict’s reagent and heat for about two minutes to test for ——-.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
sugar
Add Benedict’s reagent and heat for about two minutes to test for sugar.
It will turn any of ————— if sugar is present.
The colour depends on the concentration.
green, yellow or red
Add Benedict’s reagent and heat for about two minutes to test for sugar.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the …
Concentration
Add Benedict’s reagent and ———— to test for sugar.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
heat for about two minutes
Carbohydrase enzymes break carbohydrates down into sugars. ——- is a type of carbohydrase that breaks down starch.
Amylase
To test for ——-, add Sudan III (a fat-soluble dye).
lipids
To test for lipids, add …
Sudan III (a fat-soluble dye).
To test for lipids, add Sudan III (a fat-soluble dye).
If lipids are present, a …
red-stained oil layer will float on the water surface.
The presence of lipids can also be tested by adding …
ethanol
The presence of lipids can also be tested by adding ethanol.
The solution is ——————. If the solution turns cloudy, lipids are present.
added to water and shaken
The presence of lipids can also be tested by adding ethanol.
The solution is added to water and shaken. If the solution —————, lipids are present.
turns cloudy
Add ———- to test for proteins.
It will turn mauve or purple if proteins are present.
Biuret solution
Add Biuret solution to test for …
It will turn mauve or purple if proteins are present.
proteins
Add Biuret solution to test for proteins.
It will turn ————- if proteins are present.
mauve or purple
What does the small intestine do?
- digest food
- absorb soluble food molecules
What describes an enzyme’s active site?
- only fits one substrate
- binds to the reacting chemical
- its shape is important
When investigating the rate of enzyme activity, what factors need to be kept constant?
- pH
- temperature
- enzyme concentration
- substrate concentration
What will happen to the rate of enzyme activity if the substrate concentration is continually increased?
Rate of enzyme activity will increase and then plateau
As the substrate concentration increases, the rate of enzyme activity will initially increase.
However, the rate of enzyme activity will eventually plateau. This is because at a certain substrate concentration all of the active sites will be occupied with substrate molecules. We would say that the enzymes are …
saturated
Taq polymerase is an enzyme used in laboratories that has optimum activity at a temperature of 75°C. Suggest why it does not denature at this temperature.
It’s 3D structure contains many disuphide covalent bonds
Blood moves around the body in three types of blood vessel:
- veins
- arteries
- capillaries
Arteries transport blood from the heart to the organs. They all carry ————- blood (apart from the ————-).
- oxygenated (contains oxygen)
- pulmonary artery
Artery walls have ————-. This makes them strong and able to cope with the high pressure at which blood is pumped out by the heart.
thick layers of muscle
Artery walls have thick layers of muscle. This makes them …
strong and able to cope with the high pressure at which blood is pumped out by the heart.
Artery walls have ——-, allowing them to stretch and spring back (recoil).
elastic fibres
Artery walls have elastic fibres, allowing them to …
stretch and spring back (recoil)
In capillaries, food and oxygen moves …
out of the blood and into the cells.
In capillaries, waste products, —————-, move out of the …
- such as carbon dioxide
- cells and into the blood
Vein walls are ——- than those found in the arteries as the blood is at a ——- pressure.
- thinner
- lower
Low pressure hinders blood flow. This means that veins have a ——- cross-section through which blood can flow to counteract this.
wider
Veins have ——- to prevent the backflow of blood.
valves
Pulmonary means …
anything relating to the lungs.
Which is the only type of vein that carries oxygenated blood?
Pulmonary vein
Chambers of the heart:
- Left ventricle
- Right ventricle
- Left atrium
- Right atrium
Blood enters the heart via the …
atria
Once filled with blood, the atria contract, forcing blood down into the ——— below.
ventricles
When the ventricles contract, they force blood to —- the heart.
exit
A group of cells in the right atrium act as a …
pacemaker
Pacemakers control the …
timing of the heartbeat
Irregular heart rates can be corrected using electrical devices known as …
artificial pacemakers.
The heart receives deoxygenated blood from the body through a vein called the …
vena cava
The heart receives oxygenated blood from the lungs through the …
pulmonary vein
The heart pumps out oxygenated blood to the body through the …
aorta
The heart pumps out deoxygenated blood to the lungs through the …
pulmonary artery
The ——- arteries supply the heart muscle with oxygenated blood.
coronary
Deoxygenated blood from the body enters into the ———- of the heart.
right atrium
This deoxygenated blood is pumped out of the heart and towards the lungs by the …
right ventricle
At the lungs, the 1. blood exchanges carbon dioxide for oxygen. This is how it becomes 2.
- deoxygenated
- oxygenated (contains oxygen).
Oxygenated blood returns to the ——- of the heart
left atrium
This oxygenated blood is pumped out of the heart and to the body by the …
left ventricle
The oxygenated blood gives its oxygen to body cells in exchange for carbon dioxide.
The blood becomes deoxygenated and returns to the …
heart
Why is the human circulatory system called a double circulatory system?
The human circulatory system is called a double circulatory system because blood passes through the heart twice per circuit.
Three main components of the human circulatory system:
- blood vessels
- blood
- heart
Air is breathed into the lungs through the …
trachea (windpipe).
The trachea divides into two tubes called the …
bronchi
The bronchi divide to form …
bronchioles
The bronchioles divide until they end up in tiny air sacs called …
alveoli
Alveoli are surrounded by a network of ——-, allowing for oxygen and carbon dioxide to be exchanged between the blood in the capillaries and the air in the lungs.
capillaries
Alveoli have a —- surface area.
large
Alveoli are surrounded by a network of capillaries. This means that:
- Alveoli have a rich blood supply.
- The distance that gases need to diffuse across is small.
The alveoli in your lungs have a larger surface area to increase the rate of diffusion of oxygen and carbon dioxide. What else can increase the rate of diffusion?
- The concentration gradient - the bigger the difference in concentration between 2 areas, the faster the rate of diffusion.
- The temperature - the higher the temperature, the faster the rate of diffusion.
White blood cells can change …
shape
Platelets are suspended in …
blood plasma
White blood cells are suspended in …
blood plasma
Blood is a ——, which means it is a group of similar cells that act harmoniously to perform a similar function.
tissue
Platelets are …
small cell fragments that do not have a nucleus.
Platelets are responsible for …
triggering blood clotting at the sites of wounds.
Red blood cells have dents on each side.
We call this a …
biconcave shape.
This biconcave shape creates a ——- and allows for the rapid diffusion of oxygen in red blood cells.
large surface area
Red blood cells do not have a 1. This frees up more room for 2.
- nucleus
- haemoglobin
Red blood cells do not have a nucleus. This frees up more room for haemoglobin.
This maximises …
the amount of oxygen that they can carry
Red blood cells are small so that they can …
pass through tiny capillaries.
Haemoglobin is found in red blood cells. Haemoglobin can …
bind with oxygen in the lungs.
Haemoglobin carries oxygen which will then be …
released to the body cells to be used for respiration.
White blood cells can change shape.
This allows them to …
squeeze through the walls of blood vessels into body tissues and to engulf harmful microorganisms.
Unlike red blood cells, white blood cells have a …
nucleus
White blood cells are responsible for …
defence against infection.
Why do white blood cells change shape?
To squeeze through the walls of blood vessels into body tissues and to engulf harmful microorganisms.
Where do waste products move out of the cells and into the blood?
Capillaries
Which chamber of the heart has the thickest wall?
Left ventricle
Disease can be subdivided into two categories:
- Communicable diseases, which can be spread between organisms.
- Non-communicable diseases, which cannot be spread between organisms.
Disease is a major contributor to ill health. What are the other contributors?
- diet
- stress
- life situations
Physical problems can negatively impact upon an …
individual’s mental health
Viruses occupying cells can stimulate …
cancers
A disease that suppresses the immune system (e.g. HIV) makes individuals …
more susceptible (likely) to catching other infectious diseases.
Allergies (e.g. asthma and skin rashes) can be triggered by …
an immune reaction to a pathogen (microorganism that can cause disease)
Why is HIV dangerous?
It can suppress the immune system and makes people more susceptible to catching other infectious diseases.
Risk factors are factors that increase the probability of developing a disease. Often, non-communicable diseases arise due to the interaction (acting together) of numerous risk factors. Risk factors can be placed into one of two categories:
- lifestyle
For example, an unbalanced diet or not enough exercise. - Substances
that can be in both the individual’s body or the environment.
For example, the chemicals inhaled when smoking.
Why is it important for scientists to scrutinise the links between risk factors and the probability of getting certain diseases?
- To ensure that it is actually the risk factor that is causing the disease and not something else altogether.
- Finding causal mechanisms is the way to prove a link.
Exposure to ionising radiation (radiation that can damage cells) is a proven risk factor for …
cancer
Smoking is a proven risk factor for …
lung diseases
Poor diet, smoking and lack of exercise are proven risk factors for …
cardiovascular disease
Smoking during pregnancy is a proven risk factor for the …
low birth weight of babies.
Obesity is a proven risk factor for …
Type 2 diabetes
Excessive alcohol consumption during pregnancy is a proven risk factor for …
brain damage in babies.
Excessive alcohol intake is a risk factor for …
liver and brain damage.
From the sampled data, a graph (e.g. a bar chart) can be plotted, showing the incidence of the disease for those who …
have the risk factor and the incidence of the disease for those without.
If the risk factor can have a range of risk (e.g. number of cigarettes smoked a day) a 1. can be plotted, showing the 2.
- scatter diagram
- incidence of the disease plotted against the number of cigarettes smoked per day.
What are the most common types of graphs used for plotting risk factors?
- Bar chart
- Scatter graph
Sometimes, being older 1. the risk of developing certain diseases, like such as…
- increases
- type II diabetes, or macular degeneration (reduced eyesight).
Certain genes can 1. the risk of developing some diseases.
For example, people with a certain variant of the BRCA2 gene are more at risk of developing …
- increase
- breast cancer
When considering risk factors, scientific data uses …
samples
The coronary arteries narrow because of a …
build-up of fatty deposits.
The coronary arteries narrow because of a build-up of fatty deposits.
This reduces …
blood flow and leads to a lack of oxygen being supplied to the heart muscle.
In coronary heart disease, the —— become narrowed as a result of a build-up of fatty deposits
coronary arteries
In coronary heart disease, the coronary arteries become narrowed as a result of a …
build-up of fatty deposits
Leaky valves allow the ——. This forces your heart to do more work to circulate the same volume of blood.
This creates a strain on the heart.
backflow of blood
Leaky valves allow the backflow of blood. This forces your heart to …
This creates a strain on the heart.
do more work to circulate the same volume of blood.
Leaky valves allow the backflow of blood. This forces your heart to do more work to circulate the same volume of blood.
This creates a …
strain on the heart.
Valves that do not open fully can obstruct…
blood flow.
Valves that do not open fully can obstruct blood flow.
So,…
This also adds to the strain on the heart.
a greater force is required to force the blood through the body
Valves that do not open fully can obstruct blood flow.
So, a greater force is required to force the blood through the body.
This also adds to the —– on the heart.
strain
————— can be inserted to replace faulty valves.
Animal or artificial valves
Animal or artificial valves can be inserted to replace faulty valves.
Although this is less drastic than a heart transplant, this still involves …
major surgery and problems with blood clots can happen.
Types of Heart Valve Disease:
- Valves that don’t fully open
- Leaky valves
Benefits of artificial hearts:
- Artificial hearts are unlikely to be rejected by the patient’s immune system, so immunosuppressant drugs (prevent rejection) are unnecessary.
- Artificial hearts can also be used to provide the heart with some rest to allow it to recover.
Drawbacks of artificial hearts:
- Artificial hearts can result in long and expensive stays in hospital.
- They can also cause blood clotting, which can potentially lead to strokes.
What procedure may be necessary in the case of heart failure?
Transplant of a donor heart
Artificial hearts are unlikely to be rejected by the patient’s immune system, so ————— are unnecessary.
immunosuppressant drugs
The two common treatments for coronary heart disease are:
- stents
- statins
Stents are inserted in order to …
keep coronary arteries (arteries that supply the heart) open.
Over time, because of ————-, the artery can begin to narrow again as scar tissue builds up.
irritation caused by the stent
Over time, because of irritation caused by the stent, the artery can begin to …
narrow again as scar tissue builds up
—- must be taken to prevent blood clotting (solid lumps of blood) on the stent.
Drugs
Drugs must be taken to prevent ———————— on the stent.
blood clotting (solid lumps of blood)
Statins are drugs that can be taken to …
decrease blood cholesterol levels.
Statins help to slow down the …
build-up of fatty materials.
As with most medications, statins can have …
side effects
what are the advantages of Drugs to treat of Heart Diseases?
Often cheap to buy, and do not require surgery.
what are the advantages of Mechanical devices to treat of Heart Diseases?
Used in cases where a donor organ is not available.
what are the advantages of organic transplant to treat of Heart Diseases?
Successfully transplanted organs won’t wear down, and will function like the replaced organ.
what are the disadvantages of organic transplant to treat of Heart Diseases?
Require a suitable donor and immunosuppressants, which can increase the risk of the patient getting another disease.
what are the disadvantages of mechanical devices to treat of Heart Diseases?
Require a power supply, and may eventually wear out and need replacing.
what are the disadvantages of drugs to treat of Heart Diseases?
May have side effects, and the patient has to remember to take them.
Name the type of drug used to decrease blood cholesterol levels
statins
Immunosuppressant drugs are used to…
stop the patients immune system from rejecting the new donor organ.
Cancer is a …
group of diseases, where changes in cells lead to uncontrolled growth and division of cells.
The tumours that result from cancer (uncontrolled division of cells) are either …
malignant or benign (harmless).
Malignant tumours can 1., leading to 2.
- invade neighbouring tissues and spread throughout the body in the blood
- the creation of more secondary tumours.
Benign tumours can …
stay in a specific part of the body, often within a membrane.
Three factors have been identified to increase the risk of some cancers:
- Smoking.
- Obesity.
- UV exposure (e.g. through lots of sunbathing).
For some cancers, an increased risk of cancer can be…
E.g. some genes (that can be inherited) have been shown to cause increased susceptibility to some types of breast cancer.
inherited from your parents.
The categories of risk factors for cancer are:
- lifestyle
- genetic
Non-communicable diseases —- be spread between organisms.
cannot
What substance do statins lower the level of in our blood?
Cholesterol
Stents are inserted in order to keep the
——- arteries open.
coranary
Transplants will function like a normal organ. But transplant patients need to take drugs called immunosuppressants, which can increase the likelihood of …
infection.
Stems are examples of plant…
organs
Reproductive structures are examples of plant …
organs
Leaves are examples of plant …
organs
Roots are examples of plant …
organs
Meristem tissue can be found at the …
growing tips of roots and shoots
The undifferentiated cells of——— repeatedly divide and grow.
meristem tissue
The undifferentiated cells of meristem tissue are…
repeatedly divided and grown.
Leaves are examples of plant organs made up of different types of tissue:
- stomata
- Palisade mesophyll
- Epidermal tissue
- Spongy mesophyll
Stomata are found in the 1., these gaps facilitate (make easier) the 2., if they are open.
- lower epidermis
- diffusion of gases in and out of the leaf
When necessary, specialised (perform a specific function) guard cells are capable of ——.
e.g. in hot weather to reduce water loss.
closing these gaps
Palisade mesophyll is a 1. located 2.
- row of cells
- below the upper epidermis.
Epidermal tissue covers the…
outer surface of leaves (as well as the rest of the plant).
Spongy mesophyll contains 1. , which help with 2.
- many air spaces
- gas exchange throughout the leaf.
Palisade mesophyll are exposed to a lot of …
sunlight
Palisade mesophyll have lots of 1. to 2.
- chloroplasts (where photosynthesis takes place)
- maximise the energy transfer in photosynthesis
Mesophyll tissue is made from …
- Palisade mesophyll
- Spongy mesophyll
Root hair cells absorb water from the soil via …
osmosis (movement of water from a dilute solution to a concentrated solution).
In root hair cells, Mineral ions are taken up by ..
active transport (movement of ions and molecules across a cell membrane to an area of higher concentration).
After being absorbed by the root hair cells, the water and minerals are carried in …
xylem vessels up the stem and into the leaves.
Once the water reaches the leaves, most of it …
evaporates and the water vapour diffuses out (is lost) through open stomata.
Losing water from the leaves is called …
transpiration
This process of transpiration helps to …
pull water up from the roots
Transpiration transports …
water and the minerals dissolved in it through the plant.
Transpiration transports water and the minerals dissolved in it through the plant. Factors affecting transpiration rates include:
- Air flow
- humidity
- light intensity
- temperature
Increased air flow —— the rate of transpiration.
increases
Increased air flow carries water away from the plant’s leaves, encouraging — water to evaporate.
more
Increased humidity increases the amount of water in the air. This makes it ——— for more water to evaporate.
more difficult
Increasing humidity —– the rate of transpiration.
decreases
Increased light intensity makes water evaporate faster, which ——- the rate of transpiration.
increases
Increased temperature makes water evaporate faster, which —— the rate of transpiration.
increases
————— is used to measure the rate of transpiration.
a potometer
A potometer is used to …
measure the rate of transpiration.
describe what happens during the Measuring the Rate of Transpiration?
As water is lost through the plant’s leaves, the air bubble moves.
The speed of the bubble’s movement shows the rate of water uptake.
This is only an estimation (guess) as a small amount of the water taken up by the shoot is used in the leaves.
What apparatus is used to calculate the rate of transpiration?
potometer
When measuring the rate of transpiration with a potometer, why is the calculation only an estimate?
A small amount of the water taken up by the shoot is used in the leaves and is not transpired.
Translocation is the process by which …
food produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs.
Translocation happens through…
phloem tubes.
Phloem tubes are made up of …
columns of elongated cells that have holes in the end walls.
Phloem tubes are made up of columns of elongated cells that have holes in the end walls.
These holes allow ——– to pass between the cells.
cell sap (a liquid in plants that stores sugars, salts and amino acids)
Unlike water transport (transpiration), translocation is …
bidirectional (movement is both up and down the plant).
How do transpiration and translocation differ?
Unlike water transport (transpiration), translocation is bidirectional (movement is both up and down the plant).
——— are transported in xylem vessels up the stem and into the leaves.
Water and minerals
Xylem have lignin in the cell wall which …
strengthens and waterproofs the elongated cells.
Xylem cells are 1. , meaning that the tubes are hollow and, therefore, their 2.
- dead
- resistance to water flow is low.
Xylem have no end …
walls means that successive cells form a long tube for ease of transport.
Root hair cells have lots of 1. to ensure that there is enough 2. for the active transport of minerals up the stem.
- mitochondria
- energy
Lots of mitochondria in root hair cells ensure that there is enough energy for the …
active transport of minerals up the stem.
In root hair cells, long projections stick out from 1. to 2. the surface area over which water and minerals can be absorbed.
- the cell and into the soil
- increase
In root hair cells, long projections stick out from the cell and into the soil to increase the …
surface area over which water and minerals can be absorbed.
If water is moving via osmosis, in which direction will it flow?
From a dilute solution (high water concentration) to a concentrated solution (low water concentration)
Stomata are 1. that facilitate (make easier) the 2.
- gaps in the lower epidermis of leaves
- diffusion of gases, including evaporated water, in and out of the leaf.
To close the stomata, the guard cells …
lose water and return to a limp state.
The guard cells can open the stomata by …
taking up lots of water, causing them to swell.
When water is abundant (lots available) the plant can afford to lose water, so it opens the —— to allow gases for photosynthesis to move freely in and out of the leaf.
stomata
When water is abundant (lots available) the plant can afford to lose water.
So it …
opens the stomata to allow gases for photosynthesis to move freely in and out of the leaf.
When water is scarce (rare), stomata 1.
This is achieved by 2.
- close in order to prevent further water loss.
- guard cells returning to a limp state after they lose water.
At night, stomata close because, in the absence of sunlight, …
carbon dioxide is not required for photosynthesis.
At night, stomata close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to …
prevent water loss.
What cell is responsible for opening and closing the stomata?
guard cells
Water molecules are held together by strong intermolecular (between water molecules) forces known as hydrogen bonds.
This interaction between water molecules is known as …
cohesion
Some of the water in the leaves is used in the process of 1. Most of the water in the leaves evaporates in a process called 2.
- photosynthesis
- transpiration
- between the water molecules means water is continually pulled upwards to replace water that has been lost in the leaves by 2.
- Cohesion
- transpiration
When measuring the transpiration rate, the rate of bubble movement is equal to the …
transpiration rate
When measuring the transpiration rate,a potometer is the equipment used to measure…
transpiration rate.
what is a likely adaptation of a xerophytic plant?
fewer stomata
Xerophytic plants are specialised to …
dry habitats where water availability is low
Stomata are also needed for …
gaseous exchange.
Leaves can also have a small surface area. This reduces the surface area for …
water loss
What is the process by which food produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs?
Translocation
Which layer of a leaf contains many air spaces, which help with gas exchange throughout the leaf?
spongy mesophyll
What is the name of the tissue found at the growing tips of shoots and roots?
meristem
Through which plant vessel does translocation occur?
phloem
What would increase the rate of transpiration?
- increased temperature
- decreased humidity
- increased light intensity
The phloem transports …
food produced during photosynthesis from the leaves to the growing regions of the plants and storage organs.