B2 Flashcards
What is diffusion?
🔶The net movement of particles from an area of high concentration to low concentration
🔶passive
🔶small molecules only
Why is diffusion only sufficient for single celled organisms?
They have a large SA:V ratio (as they are smaller ) and have low metabolic demands
What are some examples of adaptations for diffusion in the body?
Alveoli/ Villi
large SA:V for diffusion of gases
Thin walls to shorten diffusion distance
Good blood supply to create a high concentration
Why is diffusion important for organisms?
In order for respiration to occur at a fast enough rate for the body to provide energy to all the organisms, through semi permeable membranes
What factors affect the rate of diffusion?
🔴Temperature- particles move faster
🔴concentration gradient- the more steeper , the faster
🔴SA, the larger the more particles can come
What is osmosis?
🌀The movement of WATER particles across a semi permeable membrane from an area of high water potential to low water potential
🌀passive process
What is water potential?
🌀The measure of FREE water particles.
🌀If there is a solute/ water concentration- the water molecules around it become ‘busy’ and therefore overall it has a low water potential
When is a solution isotonic to the cell?
When the solution and the cell have the same water potential and concentration of sugar
When is a solution hypotonic to the cell?
The outside solution has a
▫️lower concentration of sugar
▫️higher water potential
▫️osmosis solution to cell
When is a solution said to be hypertonic to a cell?
When the solution has
▫️a larger concentration of sugar
▫️lower water potential
▫️osmosis from cell outwards
What happens to a plant cell when placed in a hypotonic solution?
Water moves from outside to inside
Making it fat or turgid
What happens when a plant cell is placed in a hypertonic solution?
Water moves from cell to outside
Making it flaccid until it collapses and becomes plasmolysed
What happens when an animal cell is placed in a hypotonic solution
Hypo- low solute concentration, high w.p
Water moves from solution into cell making it swell until it burst - lysis
What happens when an animal cell is placed into a hypertonic solution?
Hyper- high solute concentration, low W.p
Water moves from cell into solution
Cell becomes cremated
What is active transport ?
⚪️Movement of particles from an area of low concentration to high concentration
⚪️requires energy
⚪️carrier proteins across the membrane
What are some examples of active transport ?
Root hair cells:
🟤Water/ mineral ions form the soil
In your gut:
🟤food from gut into the bloodstream
What is mitosis?
Cell division where one cell divides to form two identical daughter cells
Why does mitosis take place?
🔴To replace worn out cells
🔴repair damaged tissue
🔴allow growth
Describe interphase
🟢cell grows out other organelles eg: mitochondria/ribosome
🟢 46 chromosomes are replicated forming x shape
Describe mitosis
🧬The X chromosomes line up at the middle of the cell
🧬Spindle fibres pull them apart to opposite sides of the cell
Describe cytokinesis
Two identical daughter cells are made when cytoplasm and membranes divide
How is DNA replicated
- DNA unzips
2.free nucleotides bond with the exposed strands - Complementary base bonding forming DNA pairs
- Whole dna bonds forming new anti parallel strands
- Half of original and half of new
- Forms an X shape
What is cell differentiation?
A cell gaining new sub cellular structures in order for it to be suited to it’s role
How is a red blood cell a specialised cell?
🔴no nucleus, to make room for haemoglobin
🔴biconcave shape to increase SA:V , increasing diffusion
🔴full of haemoglobin to carry as much as possible
🔴flexible to fit through very narrow blood vessels
How as a sperm cell a differentiated cell ?
🔵flagellum to move the sperm to the ovum
🔵lots of mitochondria, for respiration, for energy to move
🔵acrosome to transfer genetic material to ovum
How is a fat cell a differentiated cell?
Can expand 1000x more than the original size to store fat
How are root hair cells differentiated cells?
🟤large SA:V ratio so that water can be diffused
🟤mitochondria for active transport as a lot of energy is required
🟤large vacuole helps the concentration gradient for osmosis
How are the xylem cells differentiated cells?
🟢lignin , hollow tube ,so that water can move through
🟢lignin also helps against the pressure of the water
How are palisade cells differentiated cells?
🟢full of chloroplast maximising the absorption of sunlight
🟢regular shape to allow a lot to be filled closely
What are stem cells?
Undifferentiated cells which can undergo division to produce many similar cells
Describe embryonic stem cells
👶Can differentiate into all cell types
👶Found from an embryo, when a sperm cell and egg fuse
Describe adult stem cells:
👱🏼♂️found in body tissues- bone marrow/brain
👱🏼♂️cannot form some but not all types of cells
👱🏼♂️used to repair damage
Describe meristem stem cell
🌿found in roots and shoot tips
🌿can differentiate into any type of plant and have this ability throughout life
🌿can be used to make clones of plants cheaply