Structure and functions in living organisms Flashcards
What is a polymer?
Molecule made up of many identical / similar molecules .
Biologically important polymers
Cellulose , glycogen, nucleic acid , DNA , RNA , starch and protein
What is a monomer ?
A monomer is a smaller / repeating unit / molecule from which larger molecules / polymers are made.
Testing for glucose.
Testing for starch.
Testing for proteins.
Testing for fats.
monomer / polymer
summary on monomers/polymers
Condensation/hydrolysis reaction
What is a Anabolic reaction?
build up large molecules from smaller ones.
What is a substrate?
A substance on which enzymes act.
What is an Active Site?
A region of an enzyme where the substrate attaches.
What is a catabolic reaction ?
break down large molecules into smaller ones.
What are Enzymes ?
Enzymes are proteins that act as
catalysts. They are made in all living
cells.
Enzymes, like catalysts, can be used
over and over again because they are
not used up during the reaction and
only a small amount is needed to
speed the reaction up.
Enzymes
Proteins that act as biological catalysts.
* A catalyst increases the rate of chemical reaction without being
changed by the reaction itself.
* Enzymes are essential to keep chemical reaction in our bodies fast
enough for survival.
* Without them, reactions would occur too slowly for us to be alive.
What is the lock and key theory ?
The lock and key theory is a simple model of how enzymes work.
The substrate of the reaction to be catalysed fits into the active site of the enzyme. You can think
of it like a lock and key. Once it is in place, the enzyme and the substrate bind together. The
reaction then takes place rapidly and the products are released from the surface of the enzyme.
Remember that enzymes can join small molecules together as well as break up large ones. There
are other, more complex models of how enzymes work but they are all based on the lock and key theory.
What is enzyme action?
How an enzyme molecule might work to join two other molecules together
and so form a more complicated substance (the product) is shown.
How does temperature affect enzyme activity ?
A rise in temperature increases the rate of most chemical reactions; a fall in
temperature slows them down. However, above 50 °C the enzymes, being
proteins, are denatured and stop working, showing how the shape of an
enzyme molecule could be very important if it has to fit the substances on
which it acts. Above 50 °C the shapes of enzymes are permanently changed
and the enzymes can no longer combine with the substances.
How does pH affect enzyme activity?
Acid or alkaline conditions alter the chemical properties of proteins,
including enzymes. Most enzymes work best at a particular level of pH.
The protein-digesting enzyme in your stomach, for example, works well at an
acidity of pH 2. At this pH, the enzyme amylase, from your saliva, cannot
work at all. Inside the cells, most enzymes will work best in neutral
conditions (pH 7).
The pH or temperature at which an enzyme works best is often called its
optimum pH or temperature. Conditions in the duodenum are slightly
alkaline: the optimum pH for pancreatic lipase is pH 8.
Although changes in pH affect the activity of enzymes, these effects are
usually reversible, i.e. an enzyme that is inactivated by a low pH will resume
its normal activity when its optimum pH is restored.
What is the rate of enzyme reactions?
The rate of an enzyme-controlled reaction depends on
the temperature and pH. It also depends on the concentrations of the
enzyme and its substrate.
The more enzyme molecules produced by a cell, the faster the reaction will
proceed, provided there are enough substrate molecules available. Similarly,
an increase in the substrate concentration will speed up the reaction if there
are enough enzyme molecules to cope with the additional substrate.
What are intra- and extracellular enzymes?
All enzymes are made inside cells. Most of them remain inside the cell to
speed up reactions in the cytoplasm and nucleus. These are called
intracellular enzymes (‘intra’ means ‘inside’).
In a few cases, the enzymes made in the cells are let out of the cell to do
their work outside. These are extracellular enzymes (‘extra’ means ‘outside’).
Fungi and bacteria release extracellular enzymes in order to digest their
food.
A mould growing on a piece of bread releases starch-digesting enzymes into
the bread and absorbs the soluble sugars that the enzyme produces from
the bread. In the digestive systems of animals, extracellular enzymes are
released into the stomach and intestines in order to digest the food.
What is diffusion?
Diffusion is the movement of particles from areas of high concentration to areas of low concentration until they are evenly spread. Diffusion depends upon the random movement of particles.
What is diffusion in living organisms?
How does diffusion take place in lungs?
What is osmosis ?
Osmosis is:
a special type of diffusion
it is the diffusion on water molecules from an area of high water concentration to an area of lower water concentration through a partially permeable membrane.
What is a partially permeable membrane ?
How does osmosis take place in root hair cell?
How to investigate osmosis in a potato ?
What is Active transport ?
Active transport is the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration.
How does Active Transport take place in root hair cell?
How does Active Transport take place in humans ?
What are the factors affecting the movement of substances?
What are autotrophs?
organisms that can
produce complex organic compounds
from simple inorganic molecules.
They are the PRODUCERS in a food chain.
What are heterotrophs?
organisms that
cannot produce their own food, but
acquire complex organic molecules by
consuming plants or other animals.
What is photosynthesis?
How does photosynthesis take place?
What is the photosynthesis chemical word equation ?
Why do plants need glucose?
What is a Endothermic Reaction?
Endothermic means it takes
heat IN.
What is a Exothermic Reaction?
Exothermic means releases heat.
What are factors affecting photosynthesis?
- Temperature
- CO2 concentration
- Light intensity
How does temperature affect photosynthesis?
How does temperature affect photosynthesis?
As CO2 increases m so does the rate of p/s.
How does light intensity affect photosynthesis ?
As light intensity increases, so does the rate of p/s.
Why do plants require minerals?
- For healthy growth plants also need certain
minerals - Farmers use fertilisers to add minerals to
soil. - Natural fertiliser = dead plants and animals
and organic waste. - Artificial (manufactured fertiliser) = made in
factories from chemicals.
What are the plant mineral requirements?
What is Faster? fertiliser
NPK- which contains Elements - Nitrogen , Phosphorus , Potassium
What is the outer structure of the leaf?
What does stomata do in leaves?
Stomata (stoma) on the undersurface of
leaves that allow CO2 to diffuse in and O2
to diffuse out. Water is also lost through
the stomata by transpiration.
What are leaf adaptations?
What does the waxy cuticle on the leaf do ?
Waxy cuticle –
stops too much
water from just
evaporating away
from the leaf.
Plants in hot, dry
or windy
conditions have a
thicker wax layer.
What does the Palisade layer do in a leaf?
most of the
chloroplasts are
found here,
containing
chlorophyll, the
pigment needed
for photosynthesis
What does the Spongy mesophyll layer do?
less
chloroplasts here.
Note the large
number of air
spaces.
What does the lower epidermis do in a leaf?
How to investigate the rate of photosynthesis .
The plants usually used are Elodea or Cabomba - types of pondweed
As photosynthesis occurs, oxygen gas produced is released
As the plant is in water, the oxygen released can be seen as bubbles leaving the cut end of the pondweed
The number of bubbles produced over a minute can be counted to record the rate
The more bubbles produced per minute, the faster the rate of photosynthesis
A more accurate version of this experiment is to collect the oxygen released in a test tube inverted over the top of the pondweed over a longer period of time and then measure the volume of oxygen collected
This practical can be used in the following ways:
Investigating the effect of changing light intensity.
This can be done by moving a lamp different distances away from the beaker containing the pondweed
Investigating the effect of changing temperature.
his can be done by changing the temperature of the water in the beaker
Investigating the effect of changing carbon dioxide concentration.
This can be done by dissolving different amounts of sodium hydrogen carbonate in the water in the beaker.
Investigating the effect of changing carbon dioxide concentration on the rate of photosynthesis
Care must be taken when investigating a condition to keep all other variables constant in order to ensure a fair test
For example, when investigating changing light intensity, a glass tank should be placed in between the lamp and the beaker to absorb heat from the lamp and so avoid changing the temperature of the water as well as the light intensity.
Alternative ways of measuring the gas (oxygen) given off in these experiments would be to:
measure the volume of gas produced using an inverted measuring cylinder with graduations filled with water that readings can be taken from as the water is displaced by the gas
or by using a syringe attached by a delivery tube to the funnel.
How do you test a leaf for starch.
What are the main nutrients humans need?
What does Vitamin C do ?
- Function
– Maintain healthy skin and gums - Good Food Source
– Citrus fruits, black currants, cabbage,
tomato, guava, mango - Effect of deficiency
– Scurvy - Bleeding under skin
- Bleeding gums
What does Vitamin D do?
- Function
– Needed to maintain hard bones
– Helps absorb calcium from small
intestine - Good Food Source
– Milk, cheese, egg yolk, fish liver oil
– Made in skin when exposed to sunlight - Effect of deficiency
– rickets
What does calcium do ?
- Function
– Healthy teeth and bones
– Normal blood clotting - Good Food Source
– Milk, cheese, fish - Effect of deficiency
– Rickets
– Slow blood clotting
What does Iron do?
- Function
– Formation of haemoglobin in red blood cells - Good Food Source
– Red meat, liver, kidney, eggs, green
vegetables (spinach), chocolate - Effect of deficiency
– Anaemia - Constant tiredness
- Lack of energy
What does Fibre do?
Function
– This is cellulose which we can not digest
– It adds bulk to the undigested food in the
intestines, maintaining peristalsis
* Good Food Source
– Vegetables, fruit, wholemeal bread
* Effect of deficiency
– Constipation
– Long term deficiency may lead to bowel
cancer
What does water do?
- Function
– Formation of blood, cytoplasm
– Solvent for transport of nutrients and
removal of waste
– Enzymes only work in solution - Good Food Source
– Drinks, fruits, vegetables - Effect of deficiency
– dehydration
What is the use of microorganism?
How to test fat digestion?
Take 4 test tubes and number them
1, 2, 3 and 4.
* set up the test tubes as shown in the
table below.
Add 5 drops of phenolphthalein to each
test tube
* Add sodium carbonate to each test tube
until the solution goes pink.
* Add 0.5ml of lipase to test tubes 1, 2 and
3.
* Add 0.5 ml water to test tubes 4.
* Observe your results. Try to explain what
you are observing.
Label the structure of a leaf .
What is the structure of a tooth?
What is the Duodenum?
First part of the small intestine
Receives pancreatic juice from the pancreas to chemically digest food
Ileum : the second part of the small intestine
Enzymes in the epithelia lining break down maltose and peptides
Villi increases the surface area for absorption.
What are examples of the use of energy in organisms ?
What is Aerobic respiration ?
What happens in anaerobic respiration?
In anaerobic respiration, glucose is converted (in the absence
of oxygen) to either lactate or ethanol. The ATP yield is low.
C6H12O6 → 2 C3H6O3 + 2 ATP
lactate
C6H12O6 → 2 C2H5OH + 2 CO2 + 2 ATP
ethanol
What is the chemical equation for anaerobic respiration?
What is lactic acid
What is the respiration experiment ?
Show the uptake of oxygen during respiration.
Investigate heat production by germinating peas/seeds.
Change—->
Organism—->
Repeat—>
Measurement 1—->
Measurement 2—->
Same—-> We will control the masses of the subject and the size of the
tube
We will be changing the subjects in the tubes
The maggots all should be of the same size, age and
species.
The investigation will be repeated multiple times for reliability.
The experiment has to be repeated atleast 3 times.
We will observe the change in movement of the
coloured liquid (change in oxygen volume)
5 minutes
Questions on the respiration experiments .
Answers on the respiration experiment.
What is the intercostal muscle ?
Lie between the ribs. Two sets – internal whose contraction leads to expiration and external whose contraction leads to inspiration.
What happens to the pressure in your lungs?
What diseases does smoking cause?
What are the effects of smoking on health?
What is tar?
What is nicotine ?
What does carbon monoxide do ?
Investigate the rate of respiration through the
measurement of the release of carbon dioxide
from living organisms.
Investigation:
In this investigation, we will be using three boiling tubes.
In each of the tubes, there will be each one of our subjects.
It is crucial for us to ensure that each tube will have the same amount
of hydrogen-carbonate indicator.
We will have three different subjects in this investigation, each being:
Germinating seeds
Boiled seeds
Glass beads.
Boiling the seeds will denature the enzymes present in the seed, which
will change the shape of the enzyme and the enzymes will no longer be
functioning.
We also want to make sure that the tube is airtight so no Carbon
Dioxide gas will escape.
The cotton wool is used to separate the subjects from the hydrogen-
carbonate indicator to ensure that they are not touching,
Method of Investigation :
Label each tube to avoid any confusions
In each boiling tube, pour in exactly 10cm^3 of the hydrogen-
carbonate indicator.
Next, place a cotton tube in each tube to ensure that our subjects are
not touching the hydrogen-carbonate indicator.
In the tube A, place 10 of the germinating seeds.
In tube B, place 10 boiled seeds.
Lastly, in tube C, place 10 of the glass beads.
Seal these tubes with the bung to ensure that no Carbon Dioxide gas
escapes.
Set a timer for three hours, and after three hours, observe the colour
change of the indicator solution.
Results :
The hydrogen-carbonate indicator in Tube A, with the germinating seeds, turns into a
yellow colour as the seeds are respiring and producing Carbon Dioxide gas.
In Tube B, the hydrogen-carbonate indicator remains orange as the seeds are denatured
and cannot function, which means that they cannot produce Carbon Dioxide gas.
Lastly, in Tube C, the hydrogen-carbonate indicator also remains orange as the glass
beads are not living organisms and therefore do not produce
any Carbon Dioxide gas.
These results prove that during respiration, carbon dioxide is released and therefore the
hydrogen carbonate indicator turns into a yellow colour. Furthermore, this proves that
respiration is taking place in the organisms as carbon dioxide gas is being released.
CORMMS:
Change-We will be changing the subjects in the tubes.
Organism- The seeds should be of the same species, size and age.
Repeat - The investigation will be repeated multiple times for
reliability. The experiment has to be repeated atleast 3
times
Measurement 1 - We will observe the colour change of the indicator
Measurement 2 - 3 hours
Same - We will control the size of the seeds used, the volume of
hydrogen-carbonate indicator, and size of the tube.
Investigate the rate of respiration through the
measurement of the production of heat in living
organisms during the process of respiration.
Investigation :
Sterilise the seeds in order to kill any fungi or bacteria present. Fungi and
bacteria are also living organisms that respire, and if not killed, they will
affect the investigation.
Next, boil the same amount of seeds to act as a control. Boiling seeds will
denature enzymes, and the substrate will not fit the enzyme anymore. This
means that the cellular processes needed to stay alive will eventually stop.
Pour the soaked and sterilised seeds into the vacuum flask labelled A.
It is quite important to label the flasks to ensure no confusions will occur.
Next, put the same amount of boiled and sterilised seeds into vacuum flask B.
It is also crucial to use a vacuum flask as it will insulate the seeds, which
allows us to know that the changes in temperature are only happening due
to respiration.
Insert a thermometer into each of the flasks and cover the opening
with cotton wool. This cotton wool will also simultaneously
insulate the seeds, and will ensure no heat is lost from the top of
the flask.
Next, invert the flasks and position them with clamps, so they do
not fall and stay in a specific position.
Record the temperatures of both flasks.
Leave this set up for 1-4 days.
After the time period is over, record the temperature of each flask
again.
You can also measure the change in temperature in regular
intervals.
Results :
The vacuum flask with the boiled seeds should be at room temperature,
and will have the same temperature shown before. This is because the
boiled seeds are not respiring in Flask A, which means that no heat is
being released.
The thermometer in the vacuum flask with the germinating seeds, Flask B,
should show a change and increase in temperature. This is because the
germinating seeds are respiring, and will produce heat. This proves that
respiration is an exothermic reaction as heat is being released rather than
being taken in.
CORMMS:
Change - We will be changing the subjects in the vacuum flasks.
Organism - The seeds should be of the same species, size and age.
Repeat - The investigation will be repeated multiple times for
reliability. The experiment has to be repeated atleast 3
times.
Measurement 1 - We will observe the change in temperature of the
thermometer.
Measurement 2 - after 1 day
Same - We will control the number of seeds, the temperature of
the flask at the starting point and the material and sizes of
the flasks.
Explain the importance of cell differentiation in the development of specialised cells.
The structural differences between different types of cells
enables them to perform specific functions within the organism
Cell differentiation is an important process by which a cell changes to become specialised
As an organism develops, cells differentiate to form different types of cells
Almost all of the cells in a multicellular organism will contain the same genetic information (the same genes or alleles), but depending on what role a particular cell needs to have, only some of the genes in a particular cell are used/expressed to control its development
When a cell differentiates, it develops a structure and composition of subcellular structures which enables it to carry out a certain function
For example, to form a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances
Differentiation and development
As a multicellular organism
develops, its cells differentiate to form specialised cells
In an animal, most cells differentiate at an early stage of development
As a result, animal cells lose their ability to differentiate early in the life of the organism
Specific cells in various locations throughout the body of an animal retain the ability to differentiate throughout the life of the animal
These undifferentiated cells are called adult stem cells and they are mainly involved in replacing and repairing cells (such as blood or skin cells)
Plants differ from animals in that many types of plant cells retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development
Specialised cells in animals and plants
Specialised cells are those which have developed certain characteristics in order to perform particular functions. These differences are controlled by genes in the nucleus
Cells specialise by undergoing differentiation: this is a process by which cells develop the structure and characteristics needed to be able to carry out their functions
Some examples of specialised animal and plant cells are shown in the table and images below
What are stem cells?
A stem cell is an undifferentiated cell of an organism that is capable of dividing an unlimited number of times
Stem cells can give rise to other cell types through the process of differentiation
The table below summarises different types of stem cells
embryonic stem cells are important as they help to form all of the different tissues and organs needed during development to form a whole new individual - they are totipotent
The role of adult stem cells is predominantly to replace cells lost through damage or to produce new cells for growth – although the bone marrow has to continually make new blood cells throughout life
In plants, meristem cells are unspecialised cells that can differentiate into the cells needed by the plant in regions where growth is occurring
For example, meristem cells in the roots can differentiate into root hair cells as well as other cells required in this part of the plant
The stem cells found in the meristems of plants retain the ability to differentiate into any type of plant cell throughout the life of the plant
What is stem cells in medicine ?
Modern scientific techniques mean that is possible to grow human embryos in the lab and to extract embryonic stem cells from them
These embryonic stem cells can then be encouraged to differentiate into most types of specialised cell
There is the potential for scientists and doctors to use stem cell technology to repair damaged organs by growing new tissue from stem cells
The new tissue is produced by human embryos, using genetic information from the patient
Adult stem cells can also be cultured in the lab and made to differentiate into specialised cells but of fewer types than embryonic stem cells (predominantly cells of the blood)
Stem cells could be used to cure many diseases in the future, such as diabetes and paralysis
What is Therapeutic cloning as a source of stem cells?
In therapeutic cloning, an embryo is produced with the same genes as the patient
A 5-day old embryo is the best source of embryonic stem cells
Stem cells from embryos created in this way are not rejected by the patient’s body so they may be used for medical treatment without the patient having to take drugs to suppress their immune system (which reduce the body’s ability to fight infection)
How do you evaluate the use of stem cells in medicine ?
Practical: Energy Content of a Food Sample
Apparatus:
Boiling tube
Boiling tube holder
Bunsen burner
Mounted needle
Measuring cylinder
Balance/scales
Thermometer
Water
Food samples
Method:
Use the measuring cylinder to measure out 25 cm3 of water and pour it into the boiling tube
Record the starting temperature of the water using the thermometer
Record the mass of the food sample
Set fire to the sample of food using the bunsen burner and hold the sample 2 cm from the boiling tube until it has completely burned
Record the final temperature of the water
Repeat the process with different food samples
E.g. popcorn, nuts, crisps
Results:
The larger the increase in water temperature, the more energy is stored in the sample
We can calculate the energy in each food sample using the following equation:
Error converting from MathML to accessible text.
4.2 kJ is the specific heat capacity of water, meaning that it is the energy required to raise 1 kg of water by 1 °C
1 cm3 of water has a mass of 1 g
Limitations:
Incomplete burning of the food sample
Solution: Relight the food sample until it no longer lights up
Heat energy is lost to the surroundings
Solution: Whilst heat lost means that the energy calculation is not very accurate, so long as the procedure is carried out in exactly the same way each time (with the same distance between food sample and boiling tube), we can still compare the results
What are the Advantages & Disadvantages of Vaccination
