B1- Cell structure and transport Flashcards
Magnification
How large an object will appear compared to it’s actual size
Resolution
The smallest distance that two objects can be seen as apart
Image size equation
Image size= actual size x magnification
Light microscope
Developed?
Uses what?
Magnification?
Expense?
Resolving power?
-Developed first
-Uses a beam of light
-X2000
-Cheaper
-Lower
Electron microscope
Developed?
Uses what?
Magnification?
Expense?
Resolving power?
-Developed later
-Uses beam of electrons
-X2,000,000
-Expensive, hard to care for
-Higher
How to use a microscope
Drop of water on slide, flat slice of onion, drops of iodine, dab excess with paper towel. Lower coverslip with mounted needle. Place on stage and use arms to hold. Lowest objective lens first. Coarse focus then fine focus.
Sub cellular structures in animals and plant cells
Animal- nucleus, cell membrane, cytoplasm, mitochondria, ribosome
Plant- nucleus, cell membrane, cytoplasm, mitochondria, ribosome, cell wall, vacuole, chloroplast
Def..
Nucleus?
Cytoplasm?
Cell membrane?
Mitochondria?
Controls the activities of the cell and contain genetic info
Substance where chemical reactions take place
Controls movement of substances in & out of cell
Aerobic takes place, releases energy
Def..
Ribosome?
Cell wall?
Vacuole?
Chloroplast?
Where protein synthesis takes place
Strengthens cell with cellulose
Filled w cell sap to keep cell rigid
Contain chlorophyll which absorbs sunlight for photosynthesis
What do chloroplasts, ribosomes and mitochondria look like in a diagram?
Green ovals
Joined/close together dots/ovals
Ovals may have zigzags
Examples of eukaryotes and prokaryotes cells?
Prokaryotes- bacteria
Eukaryotes- animal, plant, fungi
Prokaryotes 8 features
Has cell membrane and cytoplasm, no nucleus, circular DNA loop, could have plasmids (extra rings of DNA) or flagella, smaller, uni-cellular
Eukaryotes 6 features
Has nucleus, cell membrane and cytoplasm, DNA in nucleus, larger, uni or multi cellular
Similar features of eukaryotes and prokaryotes
Contain DNA, ribosomes, cytoplasm, cell membrane
How to calculate orders of magnitude
If bigger number divided by smaller number is close to 10=1 order, close to 100=2 orders
Specialised cell definition
Cell that has an adapted structure to perform a specific function
Red blood cell
Adaptations and Functions
No nucleus, biconcave, contains haemoglobin
Collect oxygen from lungs and carry around body
Egg cell
Adaptations and Functions
Has nucleus, round shape, mitochondria
To be fertilised and develop into foetus
Sperm cell
Adaptations and Functions
Streamline shape, flagellum, mitochondria, nucleus
To swim and fertilise egg
Nerve cell
Adaptations and Functions
Long thin axon, millions of nerve endings, mitochondria
Send and receive electrical messages
Root hair cell
Adaptations and Functions
Large epidermal extension increase sa, lots of mitochondria for active transport
Absorb water, take in minerals
Xylem
Adaptations and Functions
Thickened walls, hollow tube, dead cells, lignin walls
Carry water, dissolved minerals from roots to leaves
Phloem
Adaptations and Functions
Living cells, sieve plates, no end walls
Carry dissolved sugars and amino acids around
Striated muscle cell
Adaptations and Functions
Long thin shape when relaxed but short fat when tight, store glycogen, can be broken down for energy
Control movements in the body, contract & relax
Diffusion definition
How long does it occur?
Movement of particles from an area of high conc to area of low conc
Move until equilibrium
Net movement equation?
Particles moving in- particles moving out
4 Factors that affect the rate of diffusion
Temperature, distance, surface area, conc gradient
SA:Volume ratio in different sized animals
Large animal-small ratio
Small animal-large ratio
Examples of diffusion
2 human, 1 plant
Food molecules-Small intestine to blood
Oxygen-Alveoli to blood
Water-Soil to plant roots
Osmosis definition
Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
Water and solute in…
Dilute solution?
Concentrated solution?
High conc of water, low conc of solute
Low conc of water, high conc of solute
Partially permeable membrane
A membrane with small holes to only let through water
What happens when an animal cell is placed in a hypertonic solution?
-High conc of water, low conc of solute inside cell
-Water moves out of cell
-Cell shrivells
What happens when an animal cell is placed in a isotonic solution?
-Same conc of water and solute inside cell
-No movement of water
-Cell unchanged
What happens when an animal cell is placed in a hypotonic solution?
-High conc of water, low conc of solute outside cell
-Water moves into cell
-Cell swells and bursts
Plasmolysis
The loss of water from a plant cell by osmosis
Turgor
The pressure against the cell wall, when a cell contains lots of water
What state will a plant cell be in a hypertonic, isotonic and hypotonic solution?
Hypertonic-plasmolysed
Isotonic- flaccid
Hypotonic-turgid (normal)
How to investigate osmosis in plant cells?
-Measure 30cm3 distilled water in boiling tube
-Measure and label 30cm3 sucrose solution, conc 0.4, 0.8, 1.2mol/dm in three other tubes
-Use a cork borer to create 4 potato cylinders then use a scalpel and ruler to make them 3cm
-Weigh each cylinder and record the mass
-Put each in a boiling tube, leave for 1 hour
-Take potatoes out and roll gently on paper towel
-Record their new mass and calculate change
-Repeat experiment and calculate mean to improve accuracy
Active transport
Movement of substances from a dilute solution to a more concentrated solution using energy
Examples of active transport in plants and animals
Plants- Root hair cell, ions in soil to the cell
Animals- Human gut, glucose from intestine to blood
