B1 Flashcards
What is the features of an animal cell?
- ribosomes
- cell membrane
- nucleus
- cytoplasm
- mitochondria
What is the features of a plant cell?
- chloroplast
- nucleus
- mitochondria
- cell wall
- cell membrane
- vacuole
- cytoplasm
- ribosomes
What is the features of a bacterial cell?
- cytoplasm
- cell wall
- plasmid
- cell membrane
- single DNA loop
- (sometimes) flagellum
What’s the function of the nucleus?
- contains DNA. Controls the activities of the cell
What’s the function of the cytoplasm?
- where most chemical reactions happens
What’s the function of the mitochondria?
- the site of aerobic respiration
What’s the function of the cell membrane?
- controls which substances entering and leaving the cell
What’s the function of the ribosome?
- the site of protein synthesis
What’s the function of the chloroplast?
- where photosynthesis happens
What’s the function of the vacuole?
- contains cell sap
What’s the function of the cell wall?
- made of cellulose
- supports and strengthens the cells
Compare a plant, animal and bacteria cell
ALL THREE HAS:
- cell membrane
- cytoplasm
PLANT AND ANIMAL CELL BOTH HAS:
- nucleus
- mitochondria
- ribosomes
PLANT AND BACTERIA CELL BOTH HAS:
- cell wall
however plant cells also has:
- a vacuole
- and chloroplast
whereas a bacteria cell has:
- plasmid
- single DNA loop
- sometimes flagella
What are the key points about eukaryotes?
- eukaryotic cells are complex cells
- e.g: animal and plant cells
What are the key points about prokaryotes?
- prokaryotic cells are more simple
- they do not have a nucleus
- e.g: bacteria cell
What are the features on a microscopes?
- eyepiece
- coarse adjustment wheel
- fine adjustment wheel
- high & low power objective lens
- stage
- light
What does magnification mean?
- is how any times bigger an image is compared to an object
What does resolution mean?
- this is the ability to tell the difference between 2 points on a picture
Which microscope was invented first?
- the light microscope
Why did the invention of the more advanced microscope increase our understanding of cell?
- it allowed us to see sub-cellular structures (little parts of cells)
How would you know an image was taken with the electron microscope?
- it has a higher resolution
- so the image will be much clearer
Write the method of using a light microscope
- clip the slide onto the stage
- start with the lowest magnification objective lens
- twist the coarse adjustment to move the stage up to just below the objective lens
- move the stage down until the image is roughly in focus
- move the fine adjustment to get a clear image
- get a bigger image by using an objective lens with a higher magnification
What makes a diagram ‘good quality’ ?
- sharp pencil used
- smooth outlines of the key features - no sketching
- no shading or colouring in
- labelled with lines which don’t cross
- title, scale and magnification are all included
What’s the equation for magnification?
M = I/A
magnification = image size / actual image
m - mm (x 1000)
mm - m ( / 1000)
mm - µm ( x 1000)
µm - mm (/ 1000)
What does undifferentiated mean?
the cell is not specialised
- it can turn into any other type cell
What does differentiated mean?
- it develops into a specialised cell
- e.g: a sperm cell or nerve cell
What are the 6 specialised cell?
- sperm cell
- nerve cell
- muscle cell
- root hair cell
- xylem
- phloem
What is the function and adaptation of a sperm cell?
FUNCTION:
- to swim to the egg
ADAPTATION:
- flagellum (tail)
- mitochondria =release energy
- enzymes in head to help penetrate egg
What is the function and adaptation of a nerve cell?
FUNCTION:
- to carry nerve impulses through the body
ADAPTATION:
- long = to carry impulses long distances from CNS to muscles
- insulated with a fatty sheath = speeds up impulses
What is the function and adaptation of a muscle cell?
FUNCTION:
- to contract to allow movement
ADAPTATION:
- lots of mitochondria to release energy through respiration
What is the function and adaptation of a root hair cell?
FUNCTION:
- absorb water and nutrients from soil
ADAPTATION:
- large surface area and thin walls to speed up the rate of absorption
What is the function and adaptation of a xylem?
FUNCTION:
- transports water around the plant
ADAPTATION:
- hollow ends to make a tube for water to travel through
- thick cell walls to help support the plant
What is the function and adaptation of a phloem?
FUNCTION:
- transports dissolved sugar and amino acids around the plant
ADAPTATION:
- cells close to the phloem provide energy to transport the substances
What is mitosis?
- it is part of the cell cycle, where cells divide
What is the purpose of mitosis?
- it is done so organisms can grow and repair themselves
What happens to cell during mitosis?
- cells which have divided by mitosis are genetically identical to the parent cell
Write the stage of the cell cycle of mitosis
- the cell grows and increases the number of mitochondria and ribosomes
- DNA replicates to make 2 copies/clones of each chromosome
- the DNA lines up down the centre of the cell
- one set of DNA is pulled to each side of the cell
- the nucleus divides
- the cytoplasm and cell membranes divide and two identical cells are formed
What is a stem cell?
- it is an undifferentiated cell which can become another type of cell
What are 2 sources of stem cells in humans?
- embryos
- adult stem cells
What are the advantages and disadvantages of an embryos?
ADVANTAGES:
- can become most other types of cell
- used to treat disease e.g: diabetes/paralysis
- not rejected by the body
DISADVANTAGES:
- can cause transfer of viruses, ethical issues = embryos are potential life, religious objections (should not ‘play God’
What are the advantages and disadvantages of an adult stem cells?
ADVANTAGES:
- can form some other types of cells e.g: blood cells from bone marrow
- not rejected by the body
DISADVANTAGES:
- can cause transfer of viruses, can differentiate into fewer types of cells than embryos
What is meristem?
- plants also have stem cells - called meristem tissue
What can meristem do?
- meristem tissue can differentiate into any other type of plant cell, at any point in the plant’s life
What are the advantages of a plant stem cells - meristem tissue?
ADVANTAGES:
- can clone rare plants to stop them from going extinct
- can clone plants which have special features e.g: resistance to a disease or a very nice tasting fruit
What is the definition of diffusion?
- the spreading out of the particles from an area of higher concentration to an area of lower concentration
List 4 factors that speed up the rate of diffusion
- a big difference in concentrations (large concentration gradient)
- warmer temperature
- large surface area of the membrane
- only a short distance for the substance to diffuse
Describe how the gills of a fish and the filaments of an axolotl are adapted for efficient diffusion
FOR BOTH THE GILLS OF A FISH & FILAMENTS OF AN AXOLOTL:
- large surface area = the faster rate of diffusion as more particles as through at once
- a good blood supply to keep a large difference in concentration
- thin walls so the substances do not have to diffuse far
List 3 example of diffusion in our bodies or in the bodies of plants
- in alveoli in our lungs
- the villi of our small intestine
- the leaves and roots of plants
What is the definition of osmosis?
- is the movement of water molecules of a high concentration of water to a low concentration of water through a partially permeable membrane
What is active transport?
- moves substances from a low to a high concentration against the concentration gradient
- this needs energy which comes from respiration
Explain 2 examples of active transport
- root hair cells absorb minerals ions which are in a low concentration in the soil. plants need ions for healthy growth
- sugar is absorbed from a low concentration in small intestine, into the blood which has a higher sugar concentration. sugar molecules are used for cell respiration
Comparison between diffusion, osmosis and active transport
ALL THREE HAS:
- involves the movement of particle
DIFFUSION AND OSMOSIS BOTH HAS:
- does not need energy (passive process)
- high to low concentration
DIFFUSION AND ACTIVE TRANSPORT BOTH HAS:
- transports substances other than water
OSMOSIS AND ACTIVE TRANSPORT BOTH HAS:
- needs a semi-permeable membrane
HOWEVER DIFFUSION ONLY HAS:
- happens in gills, alveoli and leaves
ALSO OSMOSIS ONLY HAS:
- involves water only
WHEREAS ACTIVE TRANSPORT ONLY HAS:
- needs energy (active process)
- low to high concentration
