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Biology Paper 1 > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

What are the features of eukaryotic cells

A
  • Found in plants, animals, fungi and protists
  • They are 10-100 micrometers in size
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2
Q

What are the features of prokaryotic cells

A
  • 0.1-5.0 micrometers in size
  • prokaryotes are unicellular
  • Bacteria are prokaryotes
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3
Q

What do prokaryotic cells contain

A

-They do not have a nucleas
-Instead most of their genetic material is stored in a single DNA loop in the cytoplasm
- may have one or more small rings of DNA called plasmids. These plasmids can replicate and move between cells so that genetic info can be shared

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4
Q

What do prokaryotic cells contain 2

A

No mitochondria or chloroplasts
Both have cell membranes
Eukaryotic genetic material is in dna

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5
Q

What do animal cells contain

A

Cell membrane
Nucleas
Ribosomes
Mitochondria
Cytoplasm

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6
Q

What does the cell membrane do

A

Seperates the interior of the cell from the environment outside
It is selectively permeable (controls substances moving in and out of the cell)

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7
Q

What does the Nucleas do

A

Contains DNA coding for a particular protein needed to build new cells
Contains chromosomes
Enclosed in a nuclear membrane

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8
Q

What do ribosomes do

A

Responsible for proteinsynthsis

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9
Q

What does mitochondria do

A

The powerhouse of the cell
Aerobic resperation releases energy in the mitochondria providing energy for the cell

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10
Q

What does the cytoplasm do

A

A jelly like fluid that fills the cell
Where most of the cells chemical reactions take place
Contains enzymes that speed up the rate of reactions

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11
Q

What do plant cells contain

A

Cell membrane
Nucleas
Ribosomes
Mitochondria
Cytoplasm
Vacuole
Cell wall
Chloroplasts

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12
Q

What does the vacuole do?

A

A fluid filled sac that stores water
Enclosed in a membrane
Can make up as much as 90% of a plant cells volume
Improved cells rigidity

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13
Q

What does the cell wall do

A

Surrounds the cell and is made of cellulose
Increases the structural strength of the cell

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14
Q

What do the chloroplasts do

A

Where photosynthesis takes places providing food for the plant
Contains chlorophyll pigment which harvests the light needed for photosynthesis

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15
Q

What is the difference in cell differentiation in plants than in animals

A

In plants, they can differentiate throughout their lives meaning plants are able to create new tissues
In animals new tissues are rarely created by cell differentiation

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16
Q

What do bacterial cells contain

A

Cell wall and membrane
Flagella- they are whip like structures for movement
Plasmids
Cytoplasm

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17
Q

What is cell differentiation?

A

Process where a cell develops new sub cellular structures to let it perform a specific function

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18
Q

What is cell differentiation in animals

A

Almost all cells differentiate at an early stage and then lose this ability. Most specialised cells can make more of the same cell by undergoing mitosis
Others such as red blood cells which lose their nucleus cannot divide and are replaced by their adult stem cells whcih retain the ability to differentiate
In mature animals cell division mostly happens to repair or replace damaged cells as they undergo little growth

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19
Q

What is cell differentiation in plants like

A

Many types of cells retain the ability to differentiate throughout life. They only differentiate when they reach their final position in the plant but they can still re differentiate when moved to another position

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20
Q

What are the features of sperm cells

A

Tail- The “tail” is used for the cells motion. This allows sperm cells to travel
Acrosome- the acrosome at the top of the head contains an enzyme needed to penetrate an egg cell
Middle section- filled with mitochondria to provide the sperm with energy it needs to travel a long distance

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21
Q

What are the features of the nerve cells

A

Axon- Part of the cell thay electrical signals travel along. The nerve cells have long axons. This increases the distance electrical signals travels
Dendrites- Branches of a nerve cell
Several dendrites spread outwards from the cell body to transfer electrical messages to other neurones
The nerve endings have many mitochondria which supply the energy to make neurotransmitters. Allows impulse to be passed from one cell to another

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22
Q

What’s re the features of muscle cells

A

Special proteins Slide Over eachother causing the muscle to contract
Lots of mitochondria to provide energy for respiration for contraction
They can store a chemical called glycogen that is used in respiration by mitochondria

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23
Q

What are examples of cell specialisation in plants

A

Root hair cells
Xylem cells
Phloem cells

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24
Q

What are the features of root hair cells

A

The large permenant valcuole affects the speed of movement of water from the soil to the cell
Long projections- this increases the surface Area thag the plant can use to absorb water and minerals
Mitochondria to provide energy from respiration for the active transport of mineral ions to the root hair cell

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25
Q

What are the features of xylem cells

A

Open ended cells- xylem vessels are made up of a series of connected dead xylem cells
The end walls of the dead cells are broken to allow water to move through
Lignin- lignin strengthens the cell walls of xylem cells

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26
Q

What are the features of phloem cells

A

Small holes- the end walls of phloem cells contain small holes to allow food products to move up and down the phloem vessels through the plant
The energy these cells need to be alive is supplied by the mitochondria of the companion cells

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27
Q

What is magnification

A

Tells us how many times larger an image seen through a microscope is compared to the real object

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28
Q

What is resolution

A

Ability to distinguish between 2 or more objects that are close together

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29
Q

What is the equation for magnification

A

Magnification= Image size/Actual size

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30
Q

What are the features of a light microscope

A

Allows bacteria to be seen for the first time- also allows us to see plants and animals as seperate objects
However we still couldn’t tell lord of subcellular structures apart
Cheap
Portable

31
Q

What are the features of an electron microscope

A

The high detail of an electron microscope allowed scientists to see su cellular structures more clearly
Also allowed scientists to study how structures such as mitochondria. Chloroplasts and ribosomes function
Expensive
Not portable

32
Q

What is the experiment for light microscopes

A

1) Peel off an epidermis layer on the onion using forceps
2) mount onto the microscope slide with a drop of water using a pipette making sure the tissue lies flat
3) Add 2 drops of iodine solution to stain the cells
4) Place the cover slip on by first placing 1 edge down on the slide and slowly lowering the other side of the cover slip using forceps. Make sure no air bubbles are trapped
5) Remove any excess stains by soaking it with paper towels

33
Q

What are chromosomes

A

Made of molecules of DNA and are found in the Nucleas of cells

34
Q

What’s re genes

A

Chromosomes present in the cells Nucleas are made up of many different genes that encode many different

35
Q

What is the cell cycle

A

The cell cycle is the series of events involved in cell growth and division
It involves mitosis which allows for the growth, repair and asexual reproduction of cells

36
Q

What happens in the initial growth stage of cells

A

Extra ribosomes, mitochondria and other subcellular structures are produced
The cells chromosomes are replicated so that there are 2 sets of the cells chromosomes

37
Q

What happens during mitosis

A

The 2 sets of chromosomes copied during the initial growth stage are pulled to opposite ends of the cells
The Nucleas divides into 2
Cytokinesis then occurs where 2 identical daughter cells form when the cytoplasm and cell membranes divide

38
Q

What are stem cells

A

Undifferentiated cells that have not yet specialised to perform a specific function

39
Q

What are stem cells found in

A

Embryos- the stem cells in embryos can differentiate into most cells types. Can clone them and be used to replace insulin producing cells with those suffering from diabetes and neural cells for Alzheimer’s
Plant meristems-found in meristem tissue and can be used to make clones- this may be nessacary if the parent plant has desirable feature like disease resistance
Bone marrow-found in adults. Adult stem cells differentiate into fewer cell types than stem cells in embryos. Used to replace dying cells and damaged tissue

40
Q

How are stem cells used

A

Stem cell treatments- may be able to replace damaged cells in the body
Plant clones- plant stem cells can be used to quickly and cheaply produce cloned plants
Rare species in plant meristems can be cloned to protect from extinction
And crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers

41
Q

What are the disadvantages of stem cells

A

Viral infections- stem cell transplants could transfer viral infections
Ethical beliefs- ethical and religious beliefs make stem cells disagreed with
For example they believe life begins at conception meaning the embryo is alive
They view the use of embryonic stem cells as “killing” an embryo

42
Q

What is diffusion

A

The spreading out of particles of any substance or solution or particles of a gas resulting in The net movement from an area of high concentration to an area of low concentration

43
Q

What is an example of diffusion

A

Oxygen moves through the membranes of structures in the lung called alveoli into the red blood cells and is carried to cells across the body for respiration. Carbon dioxide moves from the red blood cells into the lungs to be exhaled. These movements of gases is called gas exchange
Urea moved from the liver cells into the blood plasma to be transported to the kidney for excretion

44
Q

What are the three factors that affect diffusion

A

Concentration gradient
Temperature
Surface area

45
Q

How does concentration gradient affect diffusion

A

The difference in concentration between 2 area. The bigger the different in concentration between 2 areas, the greater the concentration gradient and the faster the rate of diffusion

46
Q

How does temperature affect diffusion

A

The higher the temperature the greater the movement of particles resulting in more collisions and therefore a faster rate of diffusion

47
Q

How does surface area affect diffusion

A

A single celles organism has a relatively large surface area : volume ratio. This allows sufficient transport of molecules into and out of the cell ti meet the needs of an organism

48
Q

What are exchange surfaces

A

Surfaces that are adapted to maximise the efficiency of gas and solute exchange

49
Q

What’s re the adaptations of exchange surfaces

A

Large surface area
Thin membrane
Ventilatoon

50
Q

What do single celles organisms use diffusion for

A

Transport molecules into their body from the air- this is because they have a relatively large surface are to volume ratio. Due to their low metabolic demands, diffusion across the surface of the organism is sufficient enough to meet its needs

51
Q

How are the lungs adapted for exchanging materials

A

Oxygen is transferred to the blood and carbon dioxide is transferred to the lungs. This takes places across the surface of millions of air sacs called alveoli which are covered in capillaries which supply the blood

52
Q

How is the small intestine adapted to exchange surfaces

A

Cells have projections called villi. Digested food is absorbed over the membrane of these cells into the bloodstream

53
Q

How are the gills adapted to exchange surfaces

A

Where gas exchange takes place in fish. Water which has oxygen passes through the mouth and over the gills. Each hill has plates called gill filaments and upon these are gill lamellae which is where diffusion of oxygen into the blood and diffusion of carbon dioxide into the water takes place. Blood flows in one direction while water flows in the other

54
Q

How are the roots adapted to exchange surfaces

A

The roots of plants are adapted to take up water and mineral ions. Roots have root hair cells with large surface areas with project into the soil

55
Q

How are the leaves of the plants adapted to exchange surfaces

A

There are many different tissues to aid with gas exchange. Carbon dioxide diffuses through the stomata for photosynthesis whilst oxygen and water vapour move out through them. The stomata are controlled by guard cells which change the size of the stomata based on how much water the plant received

56
Q

How is having a large surface area an adaptation

A

The greater the surface area the more particles can move through resulting in a faster rate of diffusion
Lungs-small spherical alveoli in the lungs creates large surface area
Small intestine- cells of the small intestine have millions of villi which are projections that increase the surface area. This means digested food can be absorbed into the blood faster
Fish gills-contains lamellae to increase the surface area
Leaves- the flattened shape increases the surface area. The airspace’s inside the leaf increases the surface area so more carbon dioxide enters cells

57
Q

How does having a thin membrane an adaptation

A

Provides a short diffusion pathway allowing the process to occur faster
Lungs-alveoli and capillary walls are thin
Small intestine- villi has a single layer of surface cells

58
Q

How does having an efficient blood supply or being ventilated in animals an adaptation

A

Creates a steep concentration gradient so diffusion occurs faster
Lungs-constantly supplies oxygen to make the blood from alveoli capillaries oxygenated by exchanging it for carbon dioxide that can be breathed out. This is a constant process meaning the concentration gradient is always steep
Fish-water flows in one direction and blood flows in the other this means that a steep concentration gradient is maintained as the concentration of oxygen is always much higher in water so it’ll diffuse across

59
Q

What is osmosis

A

Water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane

60
Q

What is the experiment of light microscopes (2)

A

6) Place the slide on the stage of the microscope
7) Turn up the nosepiece to select the a low power objective
8) Set up the microscope-don’t look into the eyepiece/ instead use the coarse adjustment knob to raise the stage until the cover slip touches the objective
9) Now look into the eyepiece and turn the coarse adjustment knob to move the stage away until the image comes into focus to help avoid breaking the slide
10) turn the nose piece to select a higher power objective
11) repeat the same process as above and then look into the eyepiece and turn the fine adjustment knob until the image comes into focus
12) Make a labelled drawing of a few of the cells you can see including any features like the nucleus or cell wall. Write down the magnification
13) Repeat these steps using a prepared slide

61
Q

How do you calculate surface area to volume ratio

A

Calculated by finding the volume (l x w x h) and the surface area (length x width) and writing the ratio in the smallest while numbers
If this is large the organism is less likely to require specialised exchange surfaces and a transport system because the rate of diffusion is sufficient in supplying and removing the nessacary gases

62
Q

What is the surface area to volume ratio like in multi celles organisms

A

The surface area to volume ratio is small so they cannot rely on diffusion alone. Instead surfaces and organ systems have a number of adaptations that allow molecule to be transported in and out of cells

63
Q

How can you observe the movement of water in and out by looking at the level of water in the tube

A

If the concentration of sugar in external solution is the same as the internal there will be no movement and the solution is said to be isotonic to the cell
If the concentration of sugar in external solution is higher than the internal water moves out and the solution is said to be hypertonic to the cell
If the concentration of sugar in external solution is lower than the internal water moves in and the solution is said to be hypotonic to the cell

64
Q

What is osmosis in animals like

A

If the external solution is more dilute it will move into animal cells causing them to burst
On the other hand if the external solution is more concentrated excess water will leave the cell causing it to be shrivelled

65
Q

What is osmosis in plants like

A

If the external solution is more dilute water will move into the cell and into the vacuole causing it to swell resulting in pressure called turgid
If the external solution is less dilute water will move out of the cell and they will become soft. Eventually the cell membrane will move away from the cell wall called plasmolysis and it will die

66
Q

What is the method of osmosis

A

1) use a cork borer to cut 5 potato cylinders
2) trim the cylinders using a sharp knife and a ruler to the same length
3)accurately measure and record the length and mass of each cylinder
4) measure 10 cm3 of the 1 m sugar solution and transfer to the first boiling tube and label

67
Q

What is the method of osmosis (2)

A

5) Repeat step 4 for other concentrations of the solution and distilled water
6) add one potato cylinder to each boiling tube
7) prepare a table
8) add one potato cylinder to each boiling tube making sure the length and mass of each cylinder is known
9) leave the cylinders in the boiling tubes overnight in a test tube rack

68
Q

What is the method of osmosis (3)

A

10) Remove the cylinders from the boiling tubes and carefully blot them out to dry with paper towels
11) measure the length and mass of each cylinder and record your measurements in the table. Calculate the percentage changes for each cylinder
12) plot the graph of change in mass against the concentration of sugar solution
13) plot a graph of change in length against the concentration of sugar solution

69
Q

What is active transport

A

Active transport is the movement of particles from an area where they’re in lower concentration to an area where they’re in higher concentration against their concentration gradient. This is not as passive as diffusion is but requires energy for respiration which is why it’s called active

70
Q

What is active transport in root hairs

A

They take up water and mineral ions from the soil. Mineral ions are usually in higher concentrations in the cells meaning diffusion cannot take place
This requires energy from resperation to work

71
Q

What is active transport in the gut

A

Substances such as glucose and amino acids from your food have to move from your gut into your bloodstream
Sometimes there can be a lower concentration of sugar molecules in the gut than the blood meaning diffusion cannot take place
Active transport is required to move the sugar to the blood against its concentration gradient

72
Q

What are the differences between diffusion, osmosis and active transport

A

Diffusion and active transport involve the movement of dissolved solutes such as sugars or mineral ions whereas osmosis involves the transport of water only
In diffusion and osmosis substances move down a concentration gradient. However active transport moves substances against a concentration gradient
Active transport is an active process which means it requires energy from respiration. Conversely diffusion and osmosis are passive processes so they happen without the need for energy

73
Q

How can we use orders of magnitude to know how small a cell is

A

If an object is 10 times bigger than another we say it is 10 (to the power of 1)
If an object is 1000 times bigger we can say it’s 10 (to the power of 3)
If an object is 10 times smaller than another way we say it is 10 (to the power of -1)

74
Q

What are the regular units of cells

A

Centi-multiply unit by 0.01
Milli-multiply unit by 0.001
Micro- multiply unit by 0.000001
Nano- multiply unit by 0.000000001

Biology Paper 1 (7 decks)

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