TOPIC B1 Cell Biology Flashcards
(119 cards)
1
Q
All living things are made up of….
A
cells.
2
Q
Give 2 facts about Eukaryotic cells:
A
- They are complex.- All animal and plant cells are Eukoryotic.
3
Q
List the 5 things you will see in an Animal Cell:
A
1 - nucleus.2 - cytoplasm3 - cell membrane4 - mitochondria5 - ribosomes
4
Q
What is the role of the Nucleus?
A
Contains genetic material and control what the cell does.
5
Q
What is the role of Cytoplasm?
A
It is where most chemical reactions happen. A gel-like substance that contains enyzmes.
6
Q
What is the role of Mitochondria?
A
It is where most aerobic respiration reactions happens. Respiration transfers energy that the cell needs to work.
7
Q
What is the role of the Cell Membrane?
A
Holds the cell together and controls what goes in and out.
8
Q
What is the role of Ribosomes?
A
This is where proteins are made in the cell.
9
Q
Plants have all the bits of an animal cell plus 3 extra things:
A
- cell wall- permanent vacuole- chloroplasts
10
Q
What is the role of a Cell Wall?
A
It supports the plant cell and strengthens it. MADE OF CELLULOSE.
11
Q
What is the role of the Permanent Vacuole?
A
Contains cell sap, a weak solution of sugar and salts.
12
Q
What is the role of Chloroplasts?
A
It is where photosynthesis happens. Photosynthesis makes food for the plant. Contains a green substance called chlorophyll which absorbs light for Photosynthesis.
13
Q
Prokaryotic cells are smaller and simpler, an example is….
A
A bacterial cell.
14
Q
Do Bacterial Cells have a Nucleus?
A
NO. They have a single circular strand of DNA that floats freely in the cytoplasm.
15
Q
What are Plasmids in a Bacterial Cell?
A
Small rings of extra DNA.
16
Q
What can we use a Light microscope for?
A
To look at cells because they allow us to see individual cells and large subcellular structures (like the nucleus)
17
Q
Why are Electron microscopes better than Light microscope? (2)
A
They have a higher resolution so we can see things in more detail. (sharper image)They have a higher magnification so we can see really small things like ribosomes and plasmids or small things in detail like the internal structure of mitochondria.
18
Q
What is Magnification?
A
How many times bigger the image is than the real thing.
19
Q
Formula for Magnification:
A
MAGNIFICATION = IMAGE SIZE DIVIDED BY REAL SIZE.
20
Q
How to prepare an onion slide ready for the microscope ( 6 )
A
1) Add a drop of water to the middle of a clean slide.
2) Cut up and onion and take off one layer.
3) Use tweezers to peel off some epidermal tissue (the clear skin) from the bottom of the layer.
4) Using the tweezers place the skin into the water on the slide.
5) Add a drop of iodine solution.
6) Place a cover slip on top, try not to get any air bubbles - they will obstruct your view of the specimen.
21
Q
Iodine Solution is a stain, why are stains good?
A
They make different parts of a cell easier to see.
22
Q
How to use a light microscope to look at your slide ( 6 )
A
1) Clip the slide onto the stage.
2) Select the objective lense with the lowest magnification.
3) Use the course adjustment knob to move the stage up to just below the objective lens.
4) Look in the eyepiece. Move the stage downwards till the image is roughly focused.
5) Move the fine adjustment knob until you get a clear image of what’s on the slide.
6) If you want a bigger image use an objective lens with a higher magnification and refocus.
23
Q
How to draw your observations (6)
A
1) Use a pencil with a sharp point.2) Take up at least half of the space avaliable with clear, unbroken lines.
3) NO SHADING NO COLOURING.
4) If you are drawing cells, the subcellular structures should be drawn in proportion.
5) Include a title and write the magnification that it was observed under.
6) Label the important features using straight, uncrossed lines.
24
Q
What are Specialised Cells?
A
Cells that carry out a specific function.
25
What is the process called when a cell changes to become specialised for its job?
Differentiation.
26
What do cells develop as they change?
Different subcellular structures and turn into different types of cells.
27
When can an animal cell differintiate?
At an early stage of the animal's life.
28
When can a plant cell differentiate?
Anytime.
29
What are cells that differentiate in adult animals mainly used for?
Repairing and replacing cells such as skin or blood cells.
30
What are undifferentiated cells called?
Stem cells.
31
What function do Sperm Cells carry out?
They take the male DNA to the egg.
32
Give 3 ways a Sperm Cell is adapted to it's job:
1) It has a long tail and streamlined head to help it swim to the egg.2) packed with mitochondria to provide energy for swimming.3) It has enzymes in its head to digest through the egg cell membrane.
33
What function do Nerve Cells carry out?
They carry electrical signals from one part of the body to another.
34
Give 2 ways Nerve Cells are adapted to their job:
1) They are long to cover more distance in the body.
| 2) They have branches at the end to connect to other nerve cells and form a network through the body.
35
What function do Muscle Cells carry out?
To contract quickly.
36
Give 2 ways Muscle Cells are adapted to their job:
1) They are long so they have space to contract.
| 2) Lots of mitochondria to provide energy for contracting.
37
What function do Root Hair Cells carry out?
They are cells on the surface of plant roots - absoring water and minerals.
38
Give 2 ways Root Hair Cells are adapted to their job:
1) They grow into long "hairs" that stick out into soil.2) This gives the plant a big surface area for absorbing water and mineral ions from the soil.
39
What function do Phloem Cells carry out:
They transport food to the plant.
40
What function do Xylem Cells carry out:
They transport water to the plant.
41
How are Xylem and Phloem Cells adapted to their function? (3)
1) they form tubes.
2) to form the tubes the cells are long and joined end to end.
3) Xylem cells are hollow and Phloem have very few subcellular structures. LOTS OF SPACE for things to flow through them.
42
Where do Chromosomes live?
In the Nucleus.
43
Chromosomes contain.....
Genetic Information.
44
What are Chromosomes?
Coiled up lengths of DNA molecules.
45
Different genes control........
the development of different characteristics e.g. hair colour.
46
How many pairs of chromosomes are there in your body?
23.One from the organism's mother and one from the father.
47
What is Mitosis?
When the body cells in multicellular organisms divide to produce new cells as part of a series of stages called the cell cycle. Mitosis is the stage when the cell divides.
48
What is Mitosis used for for multicellular organisms?
To grow or replace cells that have been damaged.
49
Give 3 things a cell does BEFORE it divides:
1) In a cell that's not dividing, the DNA is all spread out in long strings.
2) The cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
3) DNA is duplicated and forms X Shaped Chromosomes. Each 'arm' of the chromosome is an exact duplicate of the other.
50
The cell is ready for division. Give the final 3 steps of the cell cycle. MITOSIS.
1) The chromosomes line up at the centre of the cell and cell fibres pull them apart - the two arms of each chromosomes go to opposite ends of the cell
.2) Memberanes form around each of the sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided
.3) Lastly, the cytoplasm and cell membrane divide.THE CELL NOW HAS PRODUCTED TWO DAUGHTER CELLS WHICH CONTAIN EXACTLY THE SAME DNA.
51
Stem cells can differentiate (change) into....
Different types of cells.
52
Why do cells differentiate (change)?
To become specialised for their job.
53
What are undifferentiated cells called?
Stem Cells.
54
Where can stem cells be found?
- Early Human Embryos.- Bone Marrow (tissue inside bones) but they can only turn into certain ones like blood cells whereas the embryonic ones can turn into anything.
55
Stem cells found in human embryos are called....
Embryonic Stem Cells.
56
Embryonic stem cells could be used to replace faulty cells in sick people. Give two examples.
You could make NERVE CELLS for people with PARALYSIS. INSULIN PRODUCING cells for people with DIABETES.
57
What's it called when you can make an embryo that has the same genes as the patient? What does this mean you can do?
Theraputic Cloning. An embryo could be made to have the same genetic information as the patient.
58
Why is Theraputic Cloning good?
The stem cells wouldn't be rejected by the person's body.
59
Give a risk involved in using stem cells in medicine:
The stem cells could be infected with a VIRUS. The virus could be PASSED on to the patient and make them SICKER.
60
Why are some people against Embryonic Stem Cells?What could you say in contrast to them?
Each embryo could be a human life.The ones used in research are UNWANTED from fertility clinics. If they weren't used for research, they would have been destroyed.
61
What are Meristems in plants?
Tissues where the growth occurs - in the tips of roots and shoots.
62
Give a fact about the stem cells in Meristems:
They can differentiate into any type of plant cell through the plant's entire life.
63
Give a pro of stem cells in Meristems:
They can make clones of plants quickly and cheaply.
64
Clones can be made of:
- rare species ( to prevent them being wiped out)
| - crop plants with useful features for farmers (e.g. plants aren't killed by a disease)
65
What is Diffusion?
Diffusion is the net movement of particles from a HIGH CONCENTRATION to a LOW CONCENTRATION until EQUILIBRIUM.
66
What small molecules can fit through cell membranes?
oxygen, glucose, water and amino acids.
67
Why does a large surface area increase diffusion rate?
More particles can pass through at the same time.
68
What is Osmosis?
Osmosis is the movement of WATER across a partially permeable membrane from a less concentrated solution (where there are lots of water molecules) to a more concentrated solution (where there a fewer water molecules).
69
What is a partially permeable membrane?
One with very small holes in it.
70
What kind of molecules can pass through a semi permeable membrane?
Tiny molecules like water - bigger molecules like sucrose can't.
71
Where do the water molecules move from in osmosis?
From the less concentrated solution (where there are lots of water molecules) to the more concentrated solution (where there are fewer water molecules).
72
Observing the effect of sugar solutions on plant tissues, POTATO PRACTICAL, give the steps: (5)
1) Cut up a potato into cylinders with the same length and width.
2) get 2 beakers: one with water and one with a very concentrated sugar solution.
3) measure the mass of each potato then put one into each beaker.
4) leave them for 24hrs.
5) take out and dry with paper towel.
73
After you measure the masses of the potato what are the conclusions?
If the mass has increased, water has moved into the potato cells. If the mass has decreased, water has moved out of the potato cells.
74
What's the only thing you should change in the potato experiment?
The concentration of the sugar solution. Things like volume of solution, temperature, time should stay the same.
75
What is Active Transport?
When substances need to be absorbed from a lower concentration to a higher concentration AGAINST A CONCENTRATION GRADIENT.
76
Plant roots are covered in millions of....
Root hair cells.
77
The root hair cells stick out into...
The soil.
78
The root hair cells have a large surface area. Why is this useful?
It is useful for absorbed by water and mineral ions from the soil.
79
Why do plants need mineral ions?
For healthy growth.
80
Why can't the root hair cells use diffusion to take up minerals from the soil?
Because the concentration of minerals is usually higher in the root hair cells than in the soil around them.
81
Active transport allows the plant to...
Absorb minerals from a very dilute solution in the soil - it moves the minerals against a concentration gradient.
82
Active transport needs...
ENERGY FROM RESPIRATION TO WORK.
83
When would active transport work in the body?
Body needs to absorb nutrients (glucose etc) to survive. The nutrients have to move from the gut into the blood. When there's a higher concentration of nutrients in the gut, they diffuse into the blood. If there is a lower concentration of nutrients in the gut then there is in the blood = ACTIVE TRANSPORT.
84
How easily stuff moves between an organism and it's environment depend on....
It's surface area to volume ratio.
85
Cells can use diffusion to take substances from the environment. What could they take?
Oxygen.
86
Cells can use diffusion to get rid of waste products. Give 2 examples.
1) carbon dioxide (from respiration)2) urea ( from the breakdown of proteins) urea diffuses from cells into the blood plasma and then is removed from body by the kidneys.
87
What does a ratio show?
How big one value is compared to another.
88
A surface area to volume ratio shows:
How big a shape's surface is compared to its volume.
89
Single celled organisms have a large surface area compared to their volume. What does this mean they can do?
They can exchange all the substances they need across the suface (cell membrane).
90
Multicellular organisms (such as animals) have a smaller surface area compared to their volume. What does this mean?
They can't normally exchange enough substances across their outside surface alone. Instead, they have specialised exchange surfaces.
91
How are exchange surfaces adapted to allow enough of different substances to pass through: (4)
1) They have a thin membrane so substances only have a short distance to diffuse.
2) They have a large surface area so lots of substances can diffuse at the same time.
3) Exchange surfaces in animals have lots of blood vessels so stuff can get in and out the blood quickly.
4) Gas exchange surfaces (e.g. alveoli) are ventilated too - air moves in and out.
92
GAS EXCHANGE IN LUNGS:What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it.
93
GAS EXCHANGE IN LUNGS:The lungs contain millions of little air sacs (where gas exchange takes place in the lungs) called...
ALVEOLI.
94
GAS EXCHANGE IN LUNGS: (3)How are alveoli specialised for diffusion?
- They have a large surface area about 75m squared in humans.- Very thin walls so gases don't have far to diffuse.- A good blood supply.- A moist lining for disolving gases.
95
The inside of the small intestine is covered in millions of....
VILLI.
96
What does VILLI do?
They increase the surface area so that digested food is absorbed quicker into the blood.
97
Give 2 features of VILLI:
- They have a single layer of surface areas.
| - They have a very good blood supply to assist quick absorption.
98
Underneath a leaf is an exchange surface. What are the small holes called that cover it?
STOMATA.
99
What controls the size of the stomata?
The guard cells. They close the stomata if the plant is losing water faster than it is being replaced by the roots. The plant would soon wilt without the guard cells.
100
The flattened shape of the leaf increases the...
Area of its exchange surface so that it is more effective.
101
Why are there air spaces inside the leaf?
To increase the area of these surfaces so there's more change for carbon dioxide to get into the cells.
102
What are the gills?
The gas exchange surface in fish.
103
Give 2 things that happen in gills:
- Water (containing oxygen) flows into the fish's mouth and passes out through the gills.
- In the gills, oxygen diffuses from the water into the blood. Carbon Dioxide diffuses from the blood into thr water.
104
What are gills made up from?
Lots of thin plates called gil filaments which give a big surface area for exchange of gases.
105
Give 3 things that make a gill well adapted:
- The thin plates give a large surface area.
- The plates have lots of blood capillaries so they have a good blood supply to speed up diffusion.
- They have a thin layer of surface cells so the gases only have to diffuse a short distance.
106
What are Eukaryotes?
Organisms that are made up of eukaryotic cells.
107
What is a Prokaryote?
A prokaryotic cell (a single celled organism)
108
The different parts of a cell are called....
Subcellular structures.
109
Light microscopes use....
Light and lenses to form an image of a specimen and magnify it (make it look bigger.)
110
Electron microscopes use...
Electrons instead of light to form an image.
111
What have some countries done about stem cell research? What about the UK?
They have banned them but in the UK it is allowed as long as it follows strict guidelines.
112
In what two things does Diffusion happen in? Why?
Solutions and Gases - because the particles in these substances are free to move about randomly.
113
What is a concentration gradient?
The difference in concentration.
114
How will a big concentration gradient impact diffusion rate?
The faster the diffusion rate.
115
Why will a higher temperature also give a faster diffusion rate?
Because the particles have more energy so they move around faster.
116
Active Transport allows nutrients to be taken into the blood despite...
The fact that the concentration gradient is the wrong way.
117
Gil filaments are covered in lots of tiny structures called...
Lamellae. These have a lot of blood capillaries to speed up diffusion.
118
How does blood flow in a lamellae? Why is this good?
Blood flows through it in one direction and water flows over in the opposite direction - this maintains a large concentration gradient between the water and the blood.
119
The concentration of oxygen in the water is....
Always higher than that in the blood, so as much oxygen as possible diffuses from the water into the blood.
