biology topic 1- cells Flashcards
where in a plant cell does photosynthesis take place?
in chloroplasts
what does the cell membrane do?
controls what goes in and out of the cell
what keeps a plant cell rigid?
cell wall
what are only visible with an electron microscope?
ribosomes
what is visible with a light microscope?
mitochondria
what is the equation for magnification?
magnification=
image size/real size
what is the equation for the magnification of the microscope?
magnification of the microscope=
magnification of eyepiece/magnification of object
what do you need to do to convert micrometres to mm?
divide by 100
what do electron microscopes use instead of light?
beams of electrons
where in the cell does protein synthesis happen?
ribosomes
what is the light microscope used for?
study living cells
what part of the cell contains DNA and controls the cell?
nucleus
where in the cell do chemical reactions happen?
cytoplasm
what do electron microscopes provide higher of?
magnification + resolution
how are the alveoli specialised to maximise the diffusion of CO2 and O2?
-an enormous surface area
-a moist lining for dissolving gas
-very thin walls
-a good blood supply
what part of a plant cell stores sap?
vacuole
what is osmosis?
diffusion of water from a dilute solution to a more concentrated solution
what is diffusion?
movement of particles from high to low concentrate
what part of the cell releases energy by respiration?
mitochondria
what is resolution?
the degree in which it is possible to distinguish between two objects that are very close together
what is active transport?
the movement of molecules across a cell membrane from a region of lower concentration to higher concentration
what are eukaryotic cells?
-plants and animals
-have a nucleus that surrounds DNA
what are prokaryotic cells?
-bacterial
-do not have a nucleus the DNA is called plasmid
what is a genome?
an entire set of gentle material in an organism to help cure disease
what are stem cells?
a cell of multicellular organism which is capable of giving more cells of the same type
what is binary fission?
the process that bacteria cells use to create copies of themselves (reproduce)
what happens in mitosis?
the cell ha produced two new daughter cells containing exactly the same DNA
where can adult stem cells be found?
-brain
-eyes
-blood
-heart
-liver
-bone marrow
-skin
-muscle
Why must inoculating loops be sterilised by passing them through a Bunsen burner flame?
To kill any bacteria present
What are chromosomes made up of?
Chromosomes consist of dna molecules combined with proteins
What are plasmids?
-small, circular loops of DNA found free in the cytoplasm
-carry genes that provide genetic advantages
List the components of both plant and animal cells
-nucleus
-cytoplasm
-cell membrane
-mitochondria
-ribosomes
List the cell components fount in ONLY plant cells
-chloroplast
-permanent vacuole
-cell wall
Describe the structure of the cytoplasm
-fluid component of the cell
-contains organelles, enzymes and dissolved ions + nutrients
Describe how sperm cells in animals are adapted to their function
-nucleus contains genetic information
-tail enables movement
-mitochondria provide energy for tail movement
Describe how nerve cells in animals are adapted to their function
-long axon allows electrical impulses to be transmitted all over the body
-dendrites from cell body connect to + receive impulses from other nerve cells, muscles and glands
Describe how muscle cells are adapted to their function
-arrangement of protein filaments allow them to slide over each other to produce muscle contraction
-mitochondria to provide energy for muscle contraction
Describe how root hair cells in plant are adapted to their function
-large surface ares to absorb nutrients from surrounding soil
-thin walls that do not restrict water absorption
Describe how xylem cells in plants are adapted to their function
-no upper or lower margins between cells to provide a continuous route for water to flow
-thick, woody side walls strengthen structure + prevent collapse
Describe how phloem cells in plants are adapted to their function
-sieve plants let dissolved amino acids + sugars be transported up + down the stem
-comparison cells provide energy needed for active transport of substances along the phloem
What is cell differenation?
The process by which cells become specialised
Define magnification
Number of times bigger an image appears compared to the size of the real object
Define resolution
Smallest distance between two objects that can be distinguished
What is a gene?
A section of DNA which codes for a protein
How many chromosomes are found in the nucleus of human body cells?
46
How many chromosomes are found in the nucleus of gametes?
23
What are the three main stages of the cell cycle?
1-replication of DNA and synthesis organelles
2-mitosis
3-division of cell
Why is mitosis important?
-produces identical cells which all have the same genetic information
-produces additional cells for growth and repair
What is a stem cell?
An unspecialised cell which is capable of differentiating into other cell types and of self-renewal
What is the function of stem cells in embryos?
-Can replicate themselves and differentiate Into many other types of cells
-May be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells
What is the function of stem cells in adult bone marrow?
Adult stem cells can differentiate into several cell types to replace dead or damaged tissues
What is the function of stem cells in plant meristems?
Meristem stem cells retain the ability to differentiate into any type of plant cell throughout their lifespan -they can differentiate into any cell which is required by the plant
What is therapeutic cloning?
A cloning method when an embryo is produced with the same genetic makeup as the patient
What are the advantages of cloning plants using meristem stem cells?
-can prevent rare plants from becoming extinct
-can produce large numbers of plants with a favourable characteristic
-can produce identical plants for research
What are the issues associated with the use of stem cells?
-development of stem cells therapies is slow, expensive and difficult
-adult stem cells infected with viruses could transfer infections to patients
What three factors affect the rate of diffusion?
-concentration gradient
-temperature
-surface area
How are single celled organisms adapted for diffusion?
They have a large surface area to volume ratio-maximises the rate of diffusion of molecules to meet the organism’s needs
