B1 Flashcards
Eukaryotic
Cells such as plant and animal cells that contain their genetic material in a nucleus
Prokaryotic
Cells such as bacterial cells that do not contain their genetic material in a nucleus
Nucleus
Controls the activities of the cell and contains the genetic material/DNA
Cell membrane
Allows substances in and out of a cell
Cytoplasm
Where the chemical reactions take place
Ribosomes
Site of protein synthesis
Mitochondria
Small organelle where energy is released from respiration
Cell wall
Supports the plant cell, made of cellulose
Chloroplasts
Contains chlorophyll and absorbs light energy for photosynthesis
Vacuole
Contains cell sap and enzymes and can store excess water
Microscopes
Instruments used to magnify objects too small to be seen with the naked eye
Resolution
The ability to distinguish between 2 points. The higher the resolution the more detail can be seen
Magnification
How many times larger an image is compared to the actual specimen
Cell differentiation
When a cell becomes specialized to carry out a specific function
Chromosomes
The structure found within a nucleus made of DNA. 23 pairs are found within most humans
Genes
A section of DNA that codes for a particular protein
Mitosis
A type of asexual cell division where an identical copy of a cell is made
Cell cycle
Where cells divide in a series of stages
Stem cell
An undifferentiated cell that can differentiate into a specialist cell
Meristem
A region in plant shoots or roots in which cells are undergoing mitosis.
Therapeutic cloning
When an embryo is produced with the same genes as the patient
Exchange surface
Generally highly folded structures found within the body where substances can move either in or out
Villi
The highly folded structures found within the small intestine that maximize the surface area for efficient digestion
alveoli
The highly folded structures found within the lungs that maximize the surface area for gaseous exchange
Diffusion
Diffusion is the movement of particles from area of high concentration to an area of low concentration
Active transport
Active transport is the movement of substances from a low concentration to a high concentration through a semi-permeable membrane
Osmosis
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially-permeable membrane
What are the main differences between Eukaryotic and prokaryotic cells?
Prokaryotes do not contain a nucleus whereas as eukaryotes do, Prokaryotes are also much smaller
List the organelles that plant and animal cells have in common
cell membrane, cytoplasm, nucleus, mitochondria, ribosomes
What additional organelles do plant cells have?
Cell wall, chloroplasts, vacuole
Why do prokaryotic cells not contain membrane bound organelles
They are too large to fit in the cell
State 2 advantages and disadvantages of the electron microscope
Advantages - high magnification, high resolution
Disadvantages - Expensive, specimen must be dead
How do you calculate magnification
Magnification = Image size ÷ Actual size
How does cell differentiation differ in plant and animal cells
Most animal cells differentiate at an early stage but most plant cells can differentiate throughout their whole life
In mature animals what is cell division generally used for
Repair and replacement of damaged tissues or cells
What is a specialized cell
One that has differentiated to have specific features which enables it to carry out a specific function (job)
What happens to a cell before it divides
The chromosomes and other organelles are copied and the chromosomes are pulled to opposite ends of the cell
Why is mitosis so important
It allows cells to be copied for growth, repair and replacement at damaged tissue
Compare human and plant stem cells
Human stem cells can be taken from an embryo or adult bone marrow. Embryonic stem cells can differentiate into most types of cells, bone marrow cells are more limited. Plant stem cells are found in meristems and can form any type of plant cell.
What factors can effect the rate of diffusion
Difference in concentrations (concentration gradient) temperature, surface area of the membrane
Where does diffusion take place
In the lungs (oxygen in and carbon dioxide out) the kidneys (urea out) and in the small intestine (nutrients diffuse into the blood stream)
Explain why single cell organisms can rely on diffusion but multicellular organisms cannot
Single-celled organisms have a larger surface area to volume ratio than multicellular organisms hence the need for multicellular organisms to have exchange surfaces and transport systems
Explain why single cell organisms can rely on diffusion but multicellular organisms cannot
Single-celled organisms have a larger surface area to volume ratio than multicellular organisms hence the need for multicellular organisms to have exchange surfaces and transport systems
What adaptations are found in most exchange surfaces
Large surface area, thin membrane to provide short diffusion distance, good blood supply (animals) to maintain the concentration gradient and being in ventilation (in animals)
Compare what happens if you put a chunk of potato in very salty water and pure water
In the very salty water the potato will lose mass as water will leave by osmosis to enter the more concentrated solution. IN pure water the potato will gain mass as water will enter by osmosis as the solution inside the plant cells is more concentrated
Explain where active transport takes place and compare it to diffusion
Active transport takes place in the roots of the plants where it allows the plant to obtain mineral ions against the concentration gradient and also in the small intestine where sugar molecules can be absorbed against the concentration gradient. It requires energy un like diffusion
What is the Plasmid
Small ring of DNA often used as a vector in genetic modification
How do you calculate number of bacteria in a certain time
Number of bacteria = n
2
Micrometre into metre
1 micrometre is 1/1000000 of a metre
Therapeutic Cloning
Embryo is produced with same genes as the patient. Stem sells can be transplanted into patient without being rejected by immune system. Once inside body, it can differentiate into cells that can fix broken cells
Where are the plant stem cells taken from
Meristem tissue, these cells can differentiate into any type of plant tissue at any point in the life of the plant
What happens to the surface area to volume ratio as an organism gets larger
Ratio falls sharply
Why is having a smaller surface area to ratio volume bad for multicellular organisms
Their surface area is not big enough for their volume meaning cells on the surface can get oxygen but cells in the center can’t as they’re too far away
How are fish adapted to gaseous exchange
.Gills increase surface area
.Filaments on gills allow oxygen from water to pass into bloodstream
.Filaments on gills have thin membrane for short diffusion path
.Filaments have efficient blood supply ensuring concentration gradient is high
What’s the importance of maintaining the concentration gradient in diffusion
.The greater the difference between the concentrations (next to each other)
the faster the rate of diffusion occurs
.If the concentrations are the same there is no net diffusion
What is the Axon
Part of the cell that electrical signals travel along.
Nerve cells have a long axon. This increases the distance that electrical signals can travel.
What is the Dendrites
Branches of a nerve cell.
Several dendrites spread outwards from the cell body to transfer electrical messages to other neurons.
Electrical messages travel between neurons at synapses.
What is the Myelin Sheath
Branches of a nerve cell.
Several dendrites spread outwards from the cell body to transfer electrical messages to other neurons.
Electrical messages travel between neurons at synapses.
Why does a muscle cell contain lots of mitochondria
To generate lots of energy for motion
Signals are transmitted across gaps between nerve cells
Synapses
What are adaptations of root hair cells
.No Chloroplasts
.Long projections (Increase surface area that plant uses to absorb water and minerals)
What is the equation for magnification
Magnification = Image size / Actual Size
How many types of sex cells are there and what are they
Sperm and egg cell
What is a stem cell
An undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells
Why are stem cells from the embryo used in therapeutic cloning not rejected by the body
Embryo is produced with the same genes as patient
What happens if you place a cell in water in terms of osmosis
Water moves into the cell by osmosis and the cell will become swollen (turgid)
