Chapter 1 Flashcards
What is osmosis?
The movement of water from a high concentration to a low one through a partially permeable membrane
Why do plants rely on osmosis?
To stay turgid
What is active transport?
When a dissolved substance moves against the concentration across a partially permeable membrane
Where does the energy for active transport come from?
Cell respiration
What does against the concentration gradient mean?
From a dilute solution to a more concentrated solution
How are nerve cells specialised?
Lots of dendrites to make connections to other nerve cells
Axon to carry impulse from one place to another
Lots of mitochondria to provide energy to make chemicals needed
long to cover longer distances
How are muscle cells specialised?
Special proteins make the fibres contract
Many mitochondria to transfer energy needed to contract and relax
Store glycogen which is used by mitochondria
How are sperm cells specialised?
Long tail and streamlines head
Many mitochondria
Digestive enzymes to break down egg wall
Large nucleus containing DNA to be passed on
Root hair cell adaptions
Large SA for water to move into cell
Large permanent vacuole to speed up osmosis
Many mitochondria to make energy needed for active transport of minerals into roots
How are photosynthetic cells adapted?
Contain chlorophyll
Positioned in outer layers of plant
Large permanent vacuole to keep cells and plant rigid
How are xylem cells adapted?
Hollow insides to allow water and minerals to move easily
Spirals of lignin in walls makes cells very strong
How are phloem cells adapted?
very few subcellular structures so stuff can flow through
Supported by companion cells that transfer mitochondria needed to move food
What is diffusion?
The spreading out of particles from a high concentration to a low one
How do you calculate the magnification of an object?
Magnification = size of image/size of real object
What is the rate of diffusion affected by?
The difference in concentrations
Temperature
Available surface area
Examples of substances that move by diffusion
Glucose
Urea (from liver to blood plasma)
Oxygen (from lungs to RBCs)
What is a dilute solution?
High concentration of water
Low concentration of solute
What is a concentrated solution?
Low concentration of water
High concentration of solute
What does isotonic mean?
Concentration of solute so in solution outside of cell is same as inside
What does hypertonic mean?
Concentration of solutes in solution is higher than inside cell
What does hypotonic mean?
Concentration of solutes in solution outside cell is lower than inside
Problems with osmosis
If solution outside cell is much more dilute, then water will move into cell by osmosis so will burst
If the solution outside cell is much more concentrated, then water will move out of cell and cell will shrivel up and die
Why do plants want the solution around cells do be hypertonic?
Water will keep moving by osmosis into the cell
What is plasmolysis?
When the vacuole and cytoplasm shrink and the cell membrane moves away from cell wall because of lack of water
What do cells involved in active transport have lots of?
Mitochondria to get maximum energy
Why is active transport so important?
Mineral ions in the soil are found in low concentrations so by using active transport, the plants can absorb these minerals
Sugar
What is key about single called organism when it comes to diffusion, active transport and osmosis?
Relatively high surface area to volume ratio
Adaptions for exchanging materials
Large SA to volume ratio
Thin membrane - short diffusion path
Efficient blood supply
Ventilation
How is the human body adapted for exchange?
Alveoli increase SA
How are fish adapted for exchange?
Gills increase SA
How are plants adapted for gas exchange?
Flat and thin leaves
Air spaces and stomata make a big SA
equation for magnification
size of image / size of real object
what is 1 nanometre?(nm)
1 x 10-9 metres
what is a micrometre? (up)
1000 nanometres
what is the resolving power of a microscope?
how much detail it can show
function of nucleus
contains activities of the cell
function of cytoplasm
where chemical reactions take place
function of cell membrane
controls movement of substances in and out
function of mitochondria
create energy
function of ribosomes
protein synthesis
which organelles are common to both animal and plant cells
nucleus membrane mitochondria ribosome cytoplasm
function of cell wall
strengthens and supports cell
what is the cell wall made from
cellulose
function of chloroplasts
contain chlorophyll for photosynthesis
function of vacuole
fills with water to keep cell turgid
what is an eukaryotic cell?
contains a nucleus with DNA
what is a prokaryotic cell?
single-celled - no nucleus
genetic material in loop or plasmids
organelles exclusive to bacteria cells
flagella, plasmids and slime capsule
function of flagella
move cell
function of slime capsule
protect cell
what characteristics should a good exchange surface hav?
large SA
thin walls
good blood supply
well ventilated
what is a tissue?
a group of cells working together to perform a specific function
what does muscular tissue do?
contracts to churn contents of stomach
what does glandular tissue do?
produces hormones
what does epithelial tissue do?
covers inside and outside of all orgns
why might you add stain to a microscope slide
to highlight certain objects by adding colour
what is the purpose of active transport in the gut?
when there is a lower concentration of nutrients in the blood than gut
how are alveoli adapted for gas exchange?
huge SA
thin
good blood supply
how is the small intestine adapted for gas exchange?
villi - increase SA
good blood supply
thin walls
how are leaves adapted for gas exchange?
the stomata let CO2 in and H2O and O2 out
size of stomata can be controlled by guard cells
air spaces in leaf increase SA
flat shape increases SA
how are fish (gills) adapted for gas exchange?
gill filaments increase SA
short diffusion pathway
good blood supply
always more O2 in water than blood so steep concentration gradient means it is more effective
advantage of light microscope
relatively cheap
advantage of electron microscope
much higher resolving power
how big is the average animal cell?
10 - 30 micrometres
how big is the average plant cell?
10 - 100 micrometres
why can diffusion take place without respiration
doesn’t need energy supply
what is the name for the apparatus which is a stick with a hoop on
innoculating loop
what are the drugs called that people with malaria are given
antiretrovirals
How do plants grow?
Photosynthesis
Creates glucose
This is used in respiration
To produce energy
Why are stem cells from embryos so good?
They are versatile and can differentiate to most cell types
What are flagella made from?
They are strings of protein
