cell biology (topic 1)✅ Flashcards
What is the function of chloroplasts?
Contain chlorophyll absorb light through photosynthesis
In which part of the cell does respiration take place
‘Mitochondria
Where is the dna found in prokaryotic cells
In the cytoplasm and plasmids
Muscle cells contain a lot of mitochondria explain why
Mitochondria transfers energy during aerobic respiration, muscles need energy to contract
What is the main function of a root hair cell?
To take up water and mineral ions from the soil
Name the chemical that makes xylem rigid
Lignin
What term is used to refer for two solutions with identical concentrations
Isotonic
How are leaves adapted to increase their surface area ?
Leaves are flat and thin and have internal air spaces and stomata
Why do some cells have large numbers of ribosomes ?
To produce large quantities of proteins
what is a cytoplasm?
a jelly-like material containing nutrients and salts where chemical reactions take place
What is the vacuole
A large sac in the middle of the cell that contains a watery solution of sugars and salts
It helps maintain the structure and shape of the cell
Define Magnification
How many times larger the image is than the object
Define resolution
The shortest distance between two points on an object that can still be distinguished as two separate entities
Which is cheaper a light microscope or an electron microscope
light microscope
Two advantages of a light microscope
Easy to use
relatively cheap
Disadvantages of a light microscope
• rely on light
• resolution is limited to 0.2 micrometer
Disadvantages of Electron microscope
• very expensive
• hard to use
Advantages of electron microscope
• use electrons instead of light
• maximum resolution is 0.1nm
• 2000x better resolution than light microscope
• can use to study sub-cellular structures
smallest to biggest measurements (5)
nm, um, mm, m , km
Roughly how large is a bacterial cell?
1 micrometer across
What is the smallest size the human eye can see
the width of a human hair
What are the three reasons why new cells are required ?
growth development and repair
How do you prepare your microscope slide to view onion cells
1) Add a drop of water to the middle of a clean slide
2) cut up an onion using scalpel and separate it out into layers. Use tweezers to peel off an epidermal tissue
3) using tweezers place epidermal tissue in water on slide
4) add a drop of iodine solution. Iodine solution is a stain . Stains are used to highlight objects in a cell by adding colour t them
5) place a colour slip on top .
How do you use a light microscope to look at your slide
1) clip the slide you’ve prepared onto the stage
2) Select the lowest powered objective lens (lowest magnification)
3) use the coarse adjustment knob to move the stage up to just below the objective lens
4) Look down the eyepiece use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
5) Adjust the focus with the fine adjustment knob until you get a clear image
Define Differentiation
Process by which cells changes to becomes specialised for its job
Examples of cells that differentiate in mature animal
Skin cells
Blood cells
What are undifferentiated cells called
Stem Cells
Name the 5 specialised cells and what they are for
• Sperm cells (reproduction)
• Nerve Cells (rapid signalling)
• Muscle cells (contraction)
• Root hair cells (absorbing water and minerals
• Phloem and Xylem Cells (transporting substances
what is the cell cycle
The series of steps that take place as a cell grows and divides
What are the 5 steps of the cell cycle
1) The cell gets larger and produces more sub-cellular structures such as mitochondria and ribosomes
2) chromosomes duplicate so that each consist of two arms
3) More cell growth
4) Mitosis- the DNA divides into two
5) Cytokinesis- the cell divides into two
Are cells produced by mitosis identical or not
Identical
How many cells are produced after the cell divides by mitosis
2
What are the 4 steps of mitosis and cytokinesis
1) DNA condenses to form chromosomes
2) Chromosomes line up against the centre of the cells
3) Cell fibres pull two arms of each chromosomes to opposite sides of the cell
4) Cytokinesis- the cell divides to form two identical daughter cells
define binary fission
the process by which prokaryotic organisms divide and reproduce
on average how often does bacteria double
once every 20 minutes
Name the parts of a bacteria cell
• Cell wall
• Cell membrane
• Plasmid
• Ribosome
• Cytoplams
• Flagellum
What two things must a bacteria cell do before it can divide
grow
duplicate genetic material
Once a bacterial cell has grown and replicated it’s genetic material it is ready to divide by binary fission
Describe the stages of this process
The two circular strands of DNA move to opposite sides of the cell
A new cell wall forms down the middle of the cell
The two halves pull apart to form two cells
What three conditions do bacteria require for fast growth
• Warm
• Moist
• Plenty of nutrients
What are two features of stem cells
• Divide by mitosis to form more cells
• Able to differentiate into specialised cells
What are the two features of Adult stem cells
• Can divide by mitosis
• Can only differentiate into different types of blood cells
Where are plant stem cells found ?
Meristems
Name the two type of stem cells found in animals
• Adult stem cells
• Embryonic stem cells
Define an embryo
a ball of cells
What are cells in the embryo also called
Embryonic stem cells
Where are adult stem cells found
Bone marrow
Which two parts of the plant contains meristem tissues
Tips of roots
Tips of shoots
What is the role of a sperm cell
Deliver genetic material to an egg in order to fertilise it
give examples of metbollic reactions in cells
• photosynthesis
• respiration
• formation of proteins
Identify two factors that embryonic stem cells have
Divide by mitosis
Differentiate into lots of different specialised cells
Identify two factors of adult stem cells
Divide by mitosis
Only differentiate into blood cells
What are stem cells used for
To replace faulty cells
What is the technique used to extract stem cells for medication
1) Extract embryonic stem cells from early embryos
2) grow them in a laboratory
3) Stimulate them to differentiate into which ever type of specialised cell
4) Give to patient to replace faulty cells
What are the drawbacks of stem cells in medicine
• Limited supply
• Ethical Issues
• Rejection
What are the risks of stem cells in medicine
• Virus transmission
• Tumour development
What does it mean when nerve cells are damaged
messages no longer be sent to muscles properly result in paralysis
What are two advantages of adult stem cells
• Taken from patient themselves, won’t cause rejection
• Taken from patient , not limited supply
Define diffusion
Movement of net particles from an area of high concentration to an area of low concentration
Define partially permeable membrane
Only some molecules can pass through membrane
3 factors affecting rate of diffusion
Concentration gradient
Temperature
Surface Area
What molecules are able to diffuse in and out of cells
• Glucose
• Amino Acids
• Water
Define Osmosis
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of high water concentration to region of lower water concentration
What happens when red blood cells are put in water
Gain water and swell
Explain the practical on the effect of osmosis on plant tissue
• First peel potatoe (skin affect osmosis)
• Use a cork borer to produce three cylinders of potato (makes all same diameter)
• Use scalpel to trim cylinders to same length
• Measure length of each cylinder using a ruler and mass of each cylinder using a balance
• now place each cylinder into a test tube , add 10cm cubes of 0.5 molar sugar solution to first tube
• add 10 cm cubed of 0.25 molar sugar solution to the second tube and 10cm cubed of distilled water to third
• leave potato cylinder overnight to allow osmosis to take place
• next remove potato cylinders and gently roll them on paper towel to remove may surface moisture
• measure length and mass of cylinders again
Why do we use distilled water instead of tap water
because distilled water contains no dissolved substances and they could affect rate of osmosis
how to calculate percentage change
change in value / original value x 100
Explain the factors of active transport
• Particles are moved against the concentration gradient
• Does require energy from respiration
Where does active transport take place in our body
lumen of small intestine
(sugars transported)
What is an example of active transport in plants
root hair cell
(ions into plants from soil)
What are the features of the sperm cell and how it helps
contains a nuclei _ to provide chromosomes for fertilisation
long tail - help the cell to swim to the egg
What are three features of nerve cell
long
branches.
insulation
What is the function of objective lens
determines resolution of the microscope
What is the function of the adjustment knob
focuses image
what does a red blood cell burst and plant cell does not burst when pit in water
water enters the cell by osmosis and plant cell has a cell wall which prevents from bursting red blood cell does not
Explain how human lungs are adapted for efficient exchange of gases by diffusion (6)
• many alveoli provide large surface area
• capillaries are thin , provide short diffusion path
•breathing bring air in and out to bring in fresh oxygen
• large capillary network to remove oxygenated blood quickly
What is the name of the enzyme which breaks down starch to produce sugars
amylase
which chemical can be used to test for glucose
benedict’s reagents
Describe the transport of water through a plant from the roots to the atmosphere
water transported in xylem
water evaporates from leaves
through the stomata
Give examples of substances transported by diffusion in the lungs and the kidney
lungs: oxygen diffuse into the blood from the lungs and carbon dioxide diffuses from the blood into the lungs
kidney : urea diffuses from cells into blood plasma
What four factors increase the effectiveness of a gas exchange surface
• large surface area
• thin membrane
• efficient blood supply
• ventilation
What happens in hypotonic solution
water moves into the cell causing it to burst
What happens in hypertonic solution
water moves out of the cell causing it to shrivel
How is active transport used to absorb the products of digestion
Active transport, transports glucose from a lower concentration in the gut to a higher concentration in the blood. Glucose is then transported to the tissues where it can be used in respiration
describe the first stage of the cell cycle
cell grows and DNA replicated and synthesises mitochondria and ribosomes
describe the second stage of the cell cycle
each chromosome is in a pair and pulled to the opposite poles of the cell then NUCLEUS divides
Describe the third stage of the cell cycle
the cytoplasm and cell membrane divide - two identical cells are produced
What are the advantages of cloning plants using meristem stem cells
• can prevent rare plants from becoming extinct
• can produce identical plants for research
• can produce large numbers of plants with a favourable characteristic
what scientific term describes the movement of water
transpiration stream
Compare the structure and function of xylem cell and phloem cell
• xylem is made up of dead cells
phloem is made up of living
• xylem does not contain cytoplasm
phloem contains cytoplasm
• xylem contains lignin
phloem does not contain lignin
both made of cells
FUNCTION
• xylem transports water ions phloem transports dissolved sugars
• xylem involved in transpiration phloem involved in translocation
