Scaling Up Flashcards
Explain diffusion and factors effecting it
Diffusion is the movement of particles from an area of high concentration to an area of low concentration. Substances can move in and out of cells across the cell membrane
Factor’s that effect it are temp, concentration gradient and surface area of membrane
Eg: CO2 in lungs goes from a low concentration to high concentration when we breathe out
Explain osmosis
Osmosis is the diffusion of water through a (partially permeable membrane) from a high concentration of water (dilute) to low concentration of water (concentrated)
The water moves to get the same concentration on both sides of the membrane
How can you test osmosis with potatoes
Cut discs of raw potatoes and measure mass of each
Put discs in different concentrations of sugar and salt solution
After 30 mins remeasure the mass of each disc
Using the masses calculate the mass change
Explain active transport
Active transport allows sugar molecules which are needed for cell respiration to be absorbed into the blood from the gut (even when the sugar concentration of the blood is higher)
In plants active transport takes place in the roots to absorb mineral ions which are necessary for growth even tho concentration of the minerals in the soil is usually lower than in the root hair
IT IS AGAINST THE CONCENTRATION GRADIENT (ACTIVE) so requires energy
What is mitosis
Mitosis is the process of dividing and replacing cells
2 daughter cells are made from 1 parent cell and they are genetically identical
First DNA is replicated as the DNA unzips and is copied the new strands then pair up causing 2 identical sets of DNA
Next the 2 identical copies of each chromosome move to opposite ends of the cell making both ends have a full set of chromosomes. Two nuclei then form
The cell then splits in half and becomes 2 new diploid cells
How are stem cells helpful
Stem cells are undifferentiated cells that have not yet specialised to perform a function. They can create more stem cells or differentiate to perform a function
In embryos they are used to differentiate into any cell needed
In bone marrow they replace dying cells
Plants use plant stem cells as they can differentiate into anything the plant needs to help it grow
What can stem cells be used for and disadvantages
Stem cells can clone plants cheaply and quickly this can protect rare plant species from extinction
Therapeutic cloning is when you take a stem cell from an embryo that will have the same DNA
Stem cell treatment is when you replace damaged cells with stem cells eg: cells that cause diabetes
Disadvantages are that it may spread viral infections and ethical beliefs as an embryo may be a life that your killing
How is the root cell adapted to perform its function
No chloroplast as it won’t need to pick up light for photosynthesis
Long projections that increase surface area that the plant can absorb water and minerals up with
What’s the function of the xylem
The xylem is a 1 way vessel that takes water from the roots to the leaves
It consists of lignin that strengthens the vessel, broken end walls to allow water through and a cell wall to keep a structure
What’s the function of the phloem
The phloem is specialised to transport food products to parts of the plant. The end cells contain holes to allow food up and down the vessels
Explain the heart
Blood enters via the Vena Cava
The atria sends blood down into the right ventricle which then goes out to the lungs from the pulmonary artery.
After blood is oxygenated it comes through the pulmonary vein to the left ventricle and pumped round the body from the aorta
Explain the red blood cells
They carry blood around the body. They are designed for this because they are a biconcave shape (large surface area), they are small in size meaning they can pass through anything, no nucleus which frees room for haemoglobin which binds with oxygen in the lungs
Explain white blood cells
They fight off infections. They are made for this as they can change shape.
Explain platelets
They trigger blood clots
Explain the affecting factors of transpiration
Air flow can cause water to evaporate more this increases transpiration
Light intensity makes water evaporate faster which increases transpiration
Humidity increases the amount of water in the air this makes it harder to evaporate water
Temperature makes water evaporate faster which increases transpiration
