B1 - Cell Structure And Transport Flashcards
What are the main 5 units of measurement
> What are their sizes in comparison to each other
> What are their units
1 kilometre (km) = 1000 metres (m)
1 m = 100 centimetres (cm)
1cm = 10 millimetres (mm)
1mm = 1000 micrometres (μm)
1 μm = 1000 nanometres (nm)
When were light microscopes first develoepd
Mid - 17th century
How do light microscopes work and how much can they magnify
> they use a beam of light to form an image of an object
the best ones magnify up to x2000
When was the electron microscope invented
in the 1930s
How do electron microscopes work and how much can they magnify
> They use a beam of electrons to form an image of an object
the best ones magnify up to x2 000 000
What are the two types of electron microscopes and what are their major differences
> Transmission electron microscopes - 2D images with high magnification and resolution
Scanning electron microscopes - 3D images but lower magnifications
What are the disadvantages of electron microscopes
> very expensive
have to be kept in special temperature, pressure and humidity controlled rooms
What are the two formulas for calculating magnification
> magnification = mag. eyepiece lens x mag. objective lens
magnification = image size / real size of object
What is resolution
the ability to distinguish between two different points
What is resolving power and what is the resolving power of light and electron microscopes
> resolving power affects how much detail a microscope can show
a light microscope has a resolving power of around 200nm
an electron microscope has a resolving power of around 0.2nm
How big are animal cells
around 10-30 μm
How big are plant cells
around 10-100 μm
What are the main structures within an animal cell (5)
> What are their main functions
> nucleus - (controls activities of the cell)
cytoplasm - (liquid gel-like substance where organelles are suspended, where most chemical reactions happen)
cell membrane - (controls the passage of substances into and out of the cell)
mitochondria (Structures where aerobic respiration occurs)
ribosome (Where protein-synthesis takes place)
What are the main structures in a plant cell (8)
> What are their main functions
> chloroplasts - (where photosynthesis occurs in green areas of plants)
Permanent vacuole - (filled with cell sap to keep the cell rigid)
cell wall - (gives the cell structural strength)
nucleus - (controls activities of the cell)
cytoplasm - (liquid gel-like substance where organelles are suspended, where most chemical reactions happen)
cell membrane - (controls the passage of substances into and out of the cell)
mitochondria (Structures where aerobic respiration occurs)
ribosome (Where protein-synthesis takes place)
What are eukaryotic cells
cells that contain a cell membrane, cytoplasm and genetic material within a nucleus
What are prokaryotic cells and how big are they
cells which do not have their genetic material enclosed within a nucleus. They are around 0.2 - 20μm
What are plasmids
extra small rings of DNA in prokaryotes that code for very specific features such as antibiotic resistance
Are bacteria eukaryotes or prokaryotes
prokaryotes
What are orders of magnitude
comparisons between sizes of objects in powers of 10
> What do nerve cells do
How are nerve cells specialised to do this (3)
> they carry electrical impulses around the body - provide rapid communication around the body
lots of dendrites to make connections with other cells
axons that carry nerve impulses from one place to
another
synapses that are adapted to pass impulses to other cells or to a muscle using transmitter chemicals
> What do muscle cells do
How are muscle cells specialised to do this (3)
> cells that can contract and relax to move bones in the body or do other bodily functions
special proteins that slide over each other, making the muscle contract
contain many mitochondria to transfer the energy needed for cells to contract and relax
they can store glycogen which can be broken down and used in cellular respiration
> What do sperm cells do
How are sperm cells specialised to do this (4)
> contain genetic information from the male parent which fertilises the egg for reproduction
long tails that help it swim faster
lots of mitochondria which provide energy for the tail
they store digestive enzymes for breaking down the outer layer of the egg
a large nucleus contains genetic information to be passed on
> What do root hair cells do
How are root hair cells specialised to do this (3)
> they help the plant to take in water from the ground
they increase surface area which speeds up osmosis
they have a large vacuole that speeds up movement of water
they have many mitochondria to provide energy for active transport
> What do photosynthetic cells do
How are photosynthetic cells specialised to do this (3)
> they photosynthesise to provide food for the plant
contain chlorophyll that trap light needed for photosynthesis
positioned in layers in the leaves to absorb as much light as possible
large permanent vacuole that helps keep the cell rigid to be as large as possible
> What do xylem cells do
How are xylem cells specialised to do this (2)
> they are the transport tissues in plants that carry water and minerals up the plant
lignin builds up in the tubes - the xylem cells then die, producing long, hollow tubes that allow water and mineral ions to pass
the rings of lignin makes the tube strong and helps withstand the pressure
> What do phloem cells do
How are phloem cells specialised to do this (2)
> the transport tissue that carries food made by photosynthesis around the body of the plant
cell walls between cells break down to form sieve plates that allow food to travel through them
they lose internal cells but are supported by companion cells. The mitochondria form these cells provide energy
What is diffusion
the spreading out of particles of any substance in a solution or gas, resulting in a net movement from an area of high concentration to an area of lower concentration down a concentration gradient
What are three factors that affect the rate of diffusion
the difference in concentration, temperature and available surface area
What is osmosis
the diffusion of water though a partially permeable membrane
What do isotonic, hypertonic and hypotonic mean
isotonic - the concentration of solutes is the same inside and outside the cell
hypertonic - the concentration of solutes is higher outside than inside the cell
hypotonic - the concentration of solutes is lower outside than outside the cell
What is turgor
the pressure formed when no more water can physically enter the plant cell, making it rigid
What does active transport do
it moves substances from a more dilute solution to a more concentrated solution against the concentration gradient
Do active transport, osmosis or diffusion require energy
active transport - yes
osmosis - no
diffusion - no
what is the relationship between SA:V ratio and size
the larger an object, the smaller the value
What are some adaptations to make exchanging materials more efficient (3)
- a large surface area
- a thin membrane
- efficient blood supply to keep the concentration gradient steep
