section a: organisms and life processes Flashcards
what eight life processes do living organisms have in common
movement, respiration, sensitivity/stimuli, growth, reproduction, excretion, nutrition, control,
give the organelles found in an unspecialized animal cell
cell membrane, cytoplasm, nucleus and mitochondria
give the organelles found in an unspecialized plant cell
cell membrane, cytoplasm, nucleus, mitochondria, cell wall, vacuole, chloroplasts
what do chloroplasts contain
chlorophyll
what are plant cell walls made of
cellulose
what do enzymes do in metabolic reactions
speed up reactions and control them.
what are enzymes known as
biological catalysts
how do cells release energy from food
they respire aerobically and anaerobically
how can substances move in and out of cells
by diffusion, osmosis and active transport
what are the levels or organisation in an organism
organelles, cells, tissues, organs and organ systems
what does a catalyst do
speeds up the reaction without getting used up
what are enzymes made of
chains of amino acids
what is an active site
the shape of the protein molecule or enzyme.
what attaches to the active site
the substrate
what happens if the shape of the active site changes
the enzyme stops working and denatures
what could change the shape of the active site/denature the enzyme
heat or pH
what is the chemical energy from food (that is broken down by cellular respiration) used for?
muscle contraction, active transport, building up large molecules and cell division
give the word equation for aerobic respiration
glucose + oxygen –> carbon dioxide and water (+ energy)
give the chemical equation for aerobic respiration
C6H12O6 + 6O2 –> 6CO2 + 6H2O (+ energy)
what is anaerobic respiration caused by
cells having to respire with no oxygen available
what are the waste products of anaerobic respiration in yeast cells
ethanol and carbon dioxide
what are the waste products of anerobic respiration in animal cells
lactic acid
how does anaerobic respiration differ from aerobic?
the glucose is not completely broken down and less energy is released
where does anaerobic respiration take place
in muscle cells during exercise.
what is oxygen debt
once the exercise stops, extra oxygen is needed to break down the lactic acid fully. the oxygen needed is called the oxygen debt.
what is diffusion
net overall movement of particles from an area of high concentration to an area of low concentration.
what is diffusion caused by
random movement of particles in gases and liquids
is diffusion passive or active
passive as it takes place down a concentration gradient and does not use energy.
what is diffusion affected by
concentration, temperature and available surface area
what is osmosis
a special type of diffusion where only water moves across a partially permeable membrane from an area of high concentration to an area of lower concentration of water down the concentration gradient.
where does osmosis take place
cell membranes are partially permeable, so osmosis takes place across cell membranes.
what is active transport
substances are moved against a concentration gradient or across a selectively permeable membrane
where does active transport get energy from
cellular respiration
features of a nerve cell that adapts it for its function
elongated axon for carrying nerve impulses.
features of a smooth muscle cell that adapts it for its function
elongated, can contract to move food through the gut
features of a sperm cell that adapts it for its function
tail for swimming, the head contains genes from the father and the middle contains mitochondria for energy.
features of a guard cell that adapts it for its function
special shape results in pore between the cells for gas exchange
features of a leaf palisade cell that adapts it for its function
packed full of chloroplasts for photosynthesis
features of a root hair cell that adapts it for its function
has a hair like filment to increase the surface area for osmosis to occur
plants:
multicellular and carry out photosynethesis
animals:
multicellular and feed on living organisms to get their energy
fungi:
multicellular or unicellular, absorb food from other living organisms
protoctists:
single-celled organisms, mainly microscopic
bacteria:
single-celled organisms, much smaller than protoctists
viruses:
even smaller than bacteria, and are parasites that reproduce inside other living cells.
examples of a plant
maize, peas, ferns
examples of an animal
humans, insects and worms
examples of fungi
moulds, yeast
examples of protoctists
protozoa, algae
examples of bacteria
lactobacillius, pneumcoccus
how do plants capture energy from the sun
using chlorophyll in their chloroplasts
what do plants store carbohydrates as
starch
can animals carry out photosynthesis
no as they dont contain chlorophyll
what do animals store carbohydrates as
glycogen
how do animals use coordination
they have nervous systems
what are vertebrates
animals that have a backbone
what are animals that dont have a backbone called
invertebrates
what are fungal cell walls made of
chitin
what are multicellular fungi made up of
a mycelium
what is a mycelium
a tangled network of thread like structures called hyphae
what is saprophytic nutrition
the secretion of enzymes by fungi which digest their load outside the cells, and then absorb the digested products. many fungi acts as composers
how do protoctists make their food
by photosynthesis (algae) or feeding on other organisms (protozoa)
what is plasmodium
a protoctist that causes malaria
what are prokaryotes
single celled organisms that do not have a nucleus
common shapes of bacteria
spheres, rods and spirals
what is a bacteria cell wall made of
polysaccharides and proteins
what organelle do bacteria not have
nucleus
where is the genetic material in bacteria
in a circular loop in the cytoplasm
what are plasmids
small extra circles of DNA in bacteria
can bacteria photosynthesize?
some contain chlorphyll and can, some feed off dead or other living organisms.
what do some bacteria have for movement
flagella
what do some bacteria have for protection
slime capsules
what is smaller, virus or bacteria
virus
where can viruses reproduce
inside the living cells of a host
what is the structure of a virus
core of genetic material surrounded by a protein coat. they either contain RNA or DNA, but not both.
can all living organisms be infected by viruses
yes including bacteria
each type of virus causes….
one specific disease in the paticular organism it is adapted to infect.
which cells dont have a nucleus
red blood cells, xylem
what does a nucleus contain
the chromozones which carry the carry the genetic material/genes (DNA)
where are proteins made
the instructions for making proteins are carried out of the nucelus into the cytoplasm, where the proteins are assembled on tiny structures called ribosomes
what controls the chemical reactions that take place in a cell
enzymes
if the cell membrane can control the movement of substances what is it
selectively permeable (not partially permeable)
what organelle is found in the cytoplasm of all living cells
mitochondria.
what do mitochondria do
carry out some of the reactions of respiration, releasing energy the cell can use
what does cell wall help the plant to do
keep its shape and is why a plant has a fixed shape.
what is cellulose
a carbohydrate
why does a plant need a cell wall
plant cells absorb water, producing an internal pressure that pushes against adjacent cells, giving the plant support. without cell walls strong enough to resist this it wouldnt be possible
if the cell wall is porous, (so it is not a barrier to water or dissolved substances), what do we call this
freely permeable
what does a vacuole contain
cell sap - sugars, mineral ions and other soutes.
why do we even need enzymes
the internal body temperature of humans is 37 degrees, so without a catalyst, all of the reactions that happen in cells would be too slow to allow life to go on.
what happens when the substrate joins up with the wnzymes active site
it lowers the energy needed for the reaction to start
optimum temp for enzymes
37 degrees
when do proteins start getting broken down by heat
above 40 degrees
is denaturing permenant
yes
pH inside cells and optimum pH for enzymes
7
what pH does pepsin have
2 (stomach)
how do you calculate rate of reaction
divide volume of (e.g. starch/what changes)
by the time it took (to change)
cm cubed divided by min or seconds
what are buffer solutions
solutions of salt that resist changes in PH.
what are buffer solutions used for
finding the effect of pH on exnzyme activity
they can also be prepared for maintaining different values of pH
practcal fto dind the effect of pHon catalase
potato is chopped into small pieces and placed in blender with an equal vol of distilled water. this release catalase from the cells. the debris sinks to the bottom and the liquid extract is removed. the extract is tested for catalase activity using a graduated syringe containing 5cm cubed of it. 5cm cubed of buffer solution pH 7 is also added. its shaken to mix the potato extract ith the buffer solutiona dn left for 5 minutes. then 5cm cubed of hydrigen oerizude solution is added and a bung is inserted and the end of the delivery tube put into a beaker of warer. bubbles willbe produced. the number of bubbles per minute is a measure of the inital reaction rate.
what is ATP used for
contraction of muscle cells
active transport of molecules and ions
building large molecules like proteins
cell division
the energy released as heat in repsiration is used to
maintina internal body temperature
aerobic respiration equation
C6H12O16 + 6O2 = 6CO2 + H2O (+energy)
how do cells pass energy to eachother
using a chemical called adenosine triphosphate or ATP
what is ATP
an organic molecule (adenosine) attached to three phosphate groups. it can be broken down by losing one phosphate group and forming adenosine diphosphate
what happens when energy is needed
ATP is broken down into ADP and phosphate. during respiration it is made from the ADP AND the phosphate
during the breaking down of ATP, what is released
chemical energy which can be used to drive metabolic processes that need it
plants
multicellular
contin chloroplasts and can carry out photosynthesis
cellulose cell wallas
store carbohydrates as starch or sucrose
animals
multicellular
no chloroplasts (no photosyntheisis)
nervous coordination
store carbohydrates as glycogen
fungi
mycelium made of hyphae which contain many nuclei some are single celled cell walls of chitin saprotrophic nutrition store carbohydrates as glycogen
protoctists
microscopic single celled organisms.
bacteria
microscopic single celled organisms cell wall cell membrane cytoplasm plasmids no nucleus but contain a circular chromozone of DNA no photosynthesis feed off other living or dead organisms
virus
not licing smaller than bacteria can only reproducei nsideliving vells no cellular structure protein coat and contain one type of nucleic acid (RNA or DNA)
practical for the demonsration of the production of CO2 using small licving organims
put the small organisms in a stoppered boiling tube on the gauze platform with the indicator. the hydrogen carbonate indicator will fo yelllow (from orange) with tuhe production of carbon dioxide
practical for the demonstration that heat is produced in respiration
soak peas in water for 24 hours so they germinate.
boil other peas to kill them. each set is washed in 1% bleach solution, which acts a as a disinfectant to kill any bacteria on the surface. rinsed twice in distilled water to remove any traces of bleach. put them each in an inverted vaccuum flask with some air, it will insulate the contents so that any small temp change can be measured. the seeds produce CO2 which is denser than air. the inverted flask and cotton wool allow it to escae or it would kill the peas.
what is rate of diffusion affected by (4)
conc gradient
surfave area to volume ratio
distance over which diffusion takes place
temperature
practical for demonstration of diffusion in a jelly
petri dish contains 2cm deep of agar jelly, dyed purple with potassium permanganate/ three cubes are cut out with side lengths 2cm,1cm and 0.5 cm. they have different surface area to volumes ratio. drop them into a beaker of dilute HCl. when HCl comes into contact with potassium permanganate it goes colourless, so note the time.
what is active transport
movemnet of substances against a conc gradient using energy from respiration
adaptation def
when the structure of a cell or organism is suited to its function.
what do multicellular organisms start off as
a zygote, which then divides into 2 cells, then 4, then 8 an dso on. this is called mitosis.
what is the specialisation of cells as they divide called
differentiation.
7 main systems in the human body
digestive system gas exchange systm circulatory system excretory system nervous system endocrine system reproductive system
stem cells
paper two
what are extracellular enzymes
enzymes secreted out of cells for the purpose of saprotophic nutrition
is the hyphae divided into separeate cells
no the thread like mucor have cell walls surrounding the cytoplasm. tge cytoplasm contians many nuceli
what does eukaryotic mean
having a nucleus. eurkaryotic organisms have cells contiaing a nucleus surrounded by a membrane alonf with other membrane bound organelles, such as mitochondria or chlorplasts.
what does prokaryotic mean
before nucleus, these organisms’ cells have no nucleus mitochondria or chloroplasts.
three basic shapes of bacteria
spheres, rods and spirals
what are bacterial cells walls made o
a complex compound of sugars and proteins called peptidoglycan
how can some bacteria swim
they have flagella
what are plasmids
small circular rings of DNA, carrying some of the bacteria’s genes
whats inside a virus
core of genetic material surrounded by a protein coat. the genetic material is either DNA or RNA.
how does a virus produce
a virus can only reproduce inside another living organism or host cell, by taking over its genetic machinery. when the host dies from too many virus particles, the particles are used to infect more cells. this does not continue forever because the humans immune system can destroy viruses, if it cant the virus will kill the organism. some viruses attack the immune system itself.
give three ways in which viruses differ from other living organisms (3)
no organelles: no cytoplasm, no mitochondria
can only reproduce in other living cells
protein coat
what do multicellular organisms begin life as
zygote
what does the zygote divide into
two cells, then four, then eight and son on until the adult body contians countless millions of cells (mitosis)
what is division of the zygote called
mitosis
outline the process of mitosis of the zygote
- chromosomes in the nucelus are copied
- the nucleus splits in two (genetic info shared equally)
- the cytoplasm divides (or new cell wall develops in plants)
- and they take in food substances to supply energy and building materials so they can grow to full size
- repeat. cells become specialised to carry out particular roles. this is called differentiation
what do cells all have in common
they all have the same genes. for cells to function differently, they must produce different proteins and different genus codes for the production of different proteins.
what are stem cells
has the ability to divide many times by mitosis while remaining undifferentiated. later it can differntiate into specialised cells such as muscle or nerve cells.
what are the two types of stem cells in humans
embryonic stem cells
adult stem cells
where are embryonic stem cells found
in the early stage of development of the embryo. they can differentiate into any type of cell.
where are adult stem cells found
certain adult tissues like bone marrow, skin and the lining of intestines. they can only form other specialised tissues. e.g. bone marrow cells can divide many times but are only able to produce different types of red and white blood cells
what is stem cell therapy
using stem cells to to treat a disease or repair damaged tissues.
what are bonemarrow transplants used to treat
blood cancers
what are scientists doing with embryonic stem cells
isolating and culturing them. they are obtained from fertility clinics where parents choose to donate their unused embryos for research.
