B2 Flashcards
What is diffusion?
The net movement of particles from a region of high concentration to a region of low concentration down the concentration gradient.
What type of process is diffusion?
A passive process
What factors affect the rate of diffusion?
The distance that the particles need to move
The size of the surface area
The concentration gradient
How does the distance the particles need to move help diffusion?
The less distance, the faster the rate of diffusion
What does increasing the concentration gradient do in diffusion?
Increases the rate of diffusion
What does the size of the surface area have to do with diffusion?
Increase of surface area increases the rate of diffusion
What is osmosis?
The diffusion of water molecules across a semi permeable membrane from a high water potential to a low water potential, down the concentration gradient.
How does water potential help osmosis?
The greater the difference in water potential, the greater the rate of osmosis
What happens if the surroundings of a plant have a higher water potential?
The plant will take up water and the pressure of the cell increases, called turgor pressure. The cell becomes firm or turgid.
Wha happens if the surrounding of a pant has the same water potential?
Nothing happens as there is no net movement of water
What happens if the plant cell has a higher water potential than its surroundings?
It loses water and the turgor pressure falls causing the cell to become flaccid. Eventually, the cell contents collapse away from the cell wall.
What is a plasmolysed cell.
When the cell contents collapse away from the cell wall.
What happens in an animal cell if the surroundings have a higher water potential?
The cell will take up water, swell and it might burst which is called lysis.
What happens if an animal cell has a higher water potential than its surrounding?
The cell loses water by osmosis and it becomes crenated (it crinkles).
What is active transport?
It allows cells to move from an area of low concentration to an area of high concentration, against the concentration gradient.
What are the 3 main features of active transport?
Particles are transported against the concentration gradient
ATP is required
This process makes use of carrier proteins in the cell membrane
What are carrier proteins?
They are special proteins that stretch across the width of the cell membrane.
What does a carrier protein do?
A particular molecule that the cells requires binds to a specific carrier protein. Energy is transferred from an energy store to the protein so that it can change shape or rotate. The carrier protein transports the molecule into the cell
What does the graph look like of rate of respiration to rate of active transport?
A curve gradually increasing
What is mitosis?
Mitosis is the process by which body cells divide. Each cell divides to produce two identical daughter cells which are genetically identical to the parent cell.
What is the order of the cell cycle?
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What is the abbreviation for the order of mitosis?
PMAT
What is the interphase?
The predatory phase, DNA replication occurs
What happens during the prophase?
DNA condenses to from chromosomes, nuclear envelope breaks down
What happens during the metaphase?
The chromosomes align in the centre of the cell called the equatorial phase and the centrioles move to opposite poles and spindle fibres form.
What happens during the telophase?
Chromosomes fully move to opposite ends, nuclear envelope forms around the new nucleus
What is cytokinesis?
Cell membrane pinches inward to separate nuclei and forms 2 daughter cell
What is a stem cell?
They are undifferentiated cells that divide by mitosis
When are stem cells used in the body?
During development, growth and repair
What can stem cells form?
All types of tissues and organs
What are the two types of stem cells?
Embryonic and adult stem cells
Where are embryonic stem cells found?
In embryos
What do embryonic stem cells do?
Divide by mitosis to produce all the cells needed to make an organism and they have the ability to differentiate into all cell types
Where are adult stem cells found?
Various body tissues such as the brain, bone marrow, skin and liver
What do adult stem cells do?
Differentiate into some different types of cells, but not as many as embryonic stem cells
What particular part of plant grow where their stem cells are?
Meristems and include shoot tips, and root tips
What is different about plant stem cells and regular plant cell?
The stems cells have:
Very thin walls
Small vacuoles
No chloroplasts
Why can’t differentiated plant cells divide?
Because their cell walls are thick and rigid
What is the circulatory system?
It is made up of your heart and blood vessels and the blood transports substances around your body to the cells that needs them and carries waste products away.
What do the arteries do?
Carry blood away from the heart at a high pressure
What do veins do?
They return blood to the heart and have valves to stop backflow.
What do the capillaries do?
They link arteries and veins in tissues and organs
What is an adaptation of the capillaries?
They have semipermeable walls that are only 1 cell thick so substances can easily move through them
What are the 3 main types of blood vessels?
Capillaries, veins and arteries
What does an artery look like?
Thick outer wall
Thick layer of muscle and elastic fibres
Small lumen
Smooth lining
What does a vein look like?
Fairly thin outer wall
Thin layer of muscles and elastic fibres
Large lumen
Smooth lining
Why is the blood leaving the heart at high pressure a good thing?
Materials are transported quickly around the body which is essential for larger organisms.
What is the order in which blood travels?
Right atrium
Right ventricle
Pulmonary artery
Lungs
Pulmonary vein
Left atrium
Left ventricle
Aorta
Vena cava
What is recoil in your arteries?
When the walls expand and the force of each contraption snaps back to push the blood forward.
Why would a human body have a double circulatory system?
Because blood flows through the heart twice during each circuit of the body
What happens when cells differentiate.
They become specialised to perform a particular job
What happens when a cell becomes specialised?
Its structure changes so that it is better adapted to perform its function.
What are some examples of specialised cells in the body?
Nerve cells
Red blood cells
Fat cells
What are examples of specialised cells in plants?
Root cells
Leaf palisade cells
What are the adaptations of a sperm cell?
Flagellum
Lots of mitochondria
Acrosome
What does the flagellum do?
Whips from side to side to propel the sperm to the ovum
What do lots of mitochondria do?
More respiration so the reactions of respiration transfer energy from chemical stores so the flagellum can move.
What does the acrosome do?
Stores digestive enzymes which break the outer layers of the ovum to allow sperm to transfer and incorporate its genetic material
How are fat cells specialised?
Small layer of cytoplasm surrounding a fat reservoir so they can expand as they fill with fat
How are red blood cells specialised?
Biconcave disks
More haemoglobin
No nucleus
Why do red blood cells have biconcave discs?
Increase the SA:V ratio to speed up diffusion of oxygen into the cell and CO2 out of the cell
Why are red blood cells full of haemoglobin?
It binds oxygen to form oxyhemoglobin
Why don’t red blood cells have a nucleus?
More space to contain haemoglobin molecules
What type of cells produce mucus?
Goblet cells which are in between ciliated cells
Who do cilia (tiny hairs) do?
They sweep the mucus from your lungs to the back of your throat . You then swallow the mucus and the bacteria are killed in the stomach
How are palisade cells specialised?
They are packed full of chloroplasts and are a regular shape to maximise the absorption of sunlight to carry out photosynthesis.
What does the coronary artery do?
Branches off aorta and supplies heart with blood and nutrients (oxygen)
How are too hair cells adapted for active transport?
They have hair-like protrusions for a high surface area to volume ratio
How are villi adapted for diffusion?
Rice blood supply for steep concentration gradient
Large surface area
Thin wall (one cell thick)
How are alveoli adapted for diffusion?
Ventilation moves air in and out (steep gradient)
Thin alveolus walls
Spherical shape (larger SA:V)
Good blood supply (concentration gradient)
How does a good blood supply in the alveoli maintain a steep concentration gradient?
It removes oxygen and brings carbon dioxide
What substances are in blood?
Red blood cells
White blood cells
Plasma
Platelets
What is plasma?
90% water and helps transports materials as many substance dissolve in plasma
What are some substances that dissolve in plasma?
Sugar, amino acids, carbon dioxide, hormones, antibodies
What does the vascular bundle do?
Transport and provide support
What is translocation?
The transport of sugar in a plant
What is the transpiration stream?
The transport of water in a plant
What is transpiration?
The water evaporating from the stomata
What does translocation happen in?
The phloem (tubes)
What is the structure of the phloem?
Living cells which have sieve plates (permeable cell walls) between them, allowing cell sap (dissolved sugar) and water to pass through
How can nutrients flow in the phloem?
2 ways to
What are xylem and phloem?
Tissues
What is the structure of the xylem?
Dead cells with no cells walls - forms tubes which water and mineral ions can pass through
What is the structure of the xylem cellulose cell walls?
Thick and stiffened with lignin to provide support - impermeable
In what way water flow in the xylem?
1 way
What does the xylem transport?
Water and mineral ions
What does the phloem transport?
Sugar from photosynthesis and other soluble food molecules
How do the vascular bundles provide support in the leaf?
In leaf - form a network that supports softer leaf tissue
How do the vascular bundles provide support in the stem?
They’re located in the outer edge providing strength to resist bending from breeze
How do the vascular bundles provide support in the roots?
Found in centre allowing it to be an anchor so the root can bend as the plant moves in the wind
How does a plant lose water?
The stomara open to gain carbon dioxide for photsythesis in the presence of light and water evaporates at this time
What factors affect the rate of transpiration?
Light intensity
Temperature
Air movement
Humidity
