Topic 1- Cells. Flashcards
1
Q
what are cells?
A
prokaryotic or eukaryotic.
2
Q
all living things are made of…?
A
cells.
3
Q
what are eukaryotic cells?
A
complex. all animal and plants are eukaryotic.
4
Q
what are prokaryotic cells?
A
smaller and simpler. bacteria are prokaryotic cells.
5
Q
what are the different parts of the cell called?
A
subcellular structures.
6
Q
what are the subcellular structures in animal cells?
A
- nucleus
- cytoplasm
- cell memebrane
- mitochondria
- ribosomes
7
Q
what is a nucleus?
A
it contains genetic material which controls what the cell does.
8
Q
what is a cytoplasm?
A
this is where most of the chemical reactions happen.
9
Q
what is a cell membrane?
A
it controls what goes in and out of the cell.
10
Q
what is a mitochondria?
A
this is where most aerobic respiration happens. (respiration transfers energy that the cell needs to work).
11
Q
what are ribosomes?
A
its where the protein are made in the cell.
12
Q
plants cells have…?
A
all the bits that animal cells have. but also has... -a cell wall -a permanent vacuole -chloroplasts
13
Q
what does a cell wall do?
A
it is made of cellulose. it supports the cell and strengthens it.
14
Q
what is a permanent vacuole?
A
it contains call sap.
15
Q
what are chloroplasts?
A
its where photosynthesis happens. (photosynthesis makes food for the plant).
16
Q
what subcellular structures does bacterial cells have?
A
- a cell wall
- cell membrane
- cytoplasm
- a single loop of DNA- bacteria doesnt have a ‘true’ nucleus.
- Plasmids- its small rings of extra DNA.
17
Q
how to estimate the area of a subcellular structure?
A
treat it like a shape. (area of rectangle- length x width= 10x1= 10 squared)
18
Q
what are microscopes?
A
they magnify things (make them look bigger).
19
Q
what are light microscopes?
A
used to look at cells . helps us see large subcellular structures (e.g: the nucleus).
20
Q
what are electron microscopes?
A
they have higher resolution than light microscopes. see things in more details.
21
Q
which one has a higher magnification?
A
electron microscopes.
22
Q
what is the formula to finding the magnification?
A
magnification= image size/real size.
they both must have same units.
magnification= 8mm/ 0.02mm = 400
23
Q
how to write 0.0025mm in standard form?
A
first number is between 1 and 10 so the decimal point needs to after the 2. 3 places to get there (power of 10). it is positive if moved left and negative if moved to the right. = 2.5 x 10 minus cubed.
24
Q
what are specialised cells?
A
they are cells that carry out a specific function. b
25
what is the process called when cells change to become specialised?
differentiation.
26
what happens when cells change?
they develop different subcellular structures. they turn into different types of cells. it allows them to carry out specific functions.
27
when does differentiation happen?
when the organism develops.
28
when does animal cells differentiate?
it only differentiates at an early stage of the animal's life.
29
when does plant cells differentiate?
they differentiate for the whole plant's life.
30
what are cells that differentiate in adult animals used for?
repairing and replacing cells.
31
what are stem cells?
cells that undifferentiated.
32
what are examples of specialised cells?
- sperm cells take the male DNA to the egg.
- nerve cells carry electrical signals around the body.
- muscle cells contract (shorten).
- root hair cells absorb water and minerals.
- phloem cells transport food and xylem cells transport water.
33
sperm cells take the male DNA to the egg...
a sperm cell has a tail to help it swim to the egg. it has a lot of mitochondria- provide energy for swimming.
34
nerve cells carry electrical signals around the body...
nerve cells are long which covers more distance in the body. they have branches at the end to connect to other nerve cells.
35
muscle cells contract (shorten)...
muscle cells are long so they have space to contract. they have lots of mitochondria. these provide energy for contracting.
36
root hair cells absorb water and minerals...
root hair cells grow into long "hairs" that stick out into the soil. it gives the plant a big surface area for absorbing water and mineral ions from the soil.
37
phloem cells transport food and xylem cells transport water...
these cells form phloem and xylem tubes. to form them the cells are long and joined end to end. xylem cells are hollow and phloem cells have very few subcellular structures- lots of space inside the cells for stuff to flow through them.
38
what do chromosomes contain?
genetic information.
39
what is inside nucleus?
chromosomes.
40
what are chromosomes?
coiled up lengths of DNA molecules.
41
what do each chromosome carry?
large number of genes.
42
what do each gene control?
they control the development of different characteristics.
43
how many copies do body cells have of each chromosome?
2.
44
how many pairs of chromosomes are there in a human cell?
23.
45
what do the multicellular organisms do?
in body cells, they divide to make new cells. this is part of a series of stages= the CELL CYCLE.
46
what are the stages if the cell cycle called when it divides?
mitosis.
47
what do multicellular organisms use mitosis for?
to grow and develop.
48
what are the main stages of the cell cycle?
- growth and DNA replication.
| - mitosis.
49
what happens in the growth and DNA replication stages?
before it divides:
- the cell grows and increases the amount of subcellular structure.
- the DNA is replicated (one copy of each new cell).
- the DNA forms X-shaped chromosomes. (each 'arm' is an exact copy of the other).
50
what is the mitosis stages of the cell cycle?
it is ready for dividing:
- chromosomes line up at the centre of the cell.
- two arms are pulled apart to opposite ends of the cell.
- this divides the nucleus.
- each set of chromosomes become the nucleus of a new cell.
- the cytoplasm and cell membrane divide.
51
the final stage of the cell cycle...
the cells has now produced two new cells:
- both contain the same DNA- IDENTICAL.
- identical to the original cell.
52
what are stem cells called when they are found in early human embryos?
embryonic stem cells. these can turn into any kind of cell.
53
what can stem cells produce?
they can produce a lots more undifferentiated cells and differentiate into different types of cell.
54
what are stem cells called when they are found in early human embryos?
embryonic stem cells.
55
where are stem cells in adults?
only in certain places like the bone marrow.
56
what can adult stem cells produce?
they can only produce certain types of specialised cell.
57
what stem cells can be cloned?
stem cells from embryos and bone marrow in a lab. can then be used for medical reasons or research.
58
what can stem cells cure?
diseases.
59
what can embryonic stem cells be used for?
to replace faulty cells in sick people.
60
examples of when embryonic cells be used?
- make nerve cells for people with paralysis.
| - insulin-producing cells for people with diabetes.
61
what is therapeutic cloning?
to make an embryo that has the same genes as the patient.
62
what does therapeutic cloning mean?
it means that the stem cells from the embryo wouldn't be rejected by the patient's body.
63
what are the dangers of therapeutic cloning?
there are risks involved in using stem cells in medicine.
64
example of a danger of therapeutic cloning?
the stem cells can be infected with a virus which could be passed on to a patient and make them sicker.
65
why are some people against stem cell research?
they think each embryo could be a human life.
66
what do others think about stem cell research?
curing patients who are suffering is more important than the rights of embryos.
67
what do they argue about stem cell research?
the embryos used in research are normally unwanted ones from the fertility clinic. they are probably going to destroy it if not used.
68
what do some people think about stem cell research?
that scientists should find other ways of stem cells.
69
what can stem cells produce?
identical plants.
70
what is meristems?
they are tissues in the plants. this is where the growth happens in the tips of roots and shoots.
71
what do meristems contain?
they contain stem cells which can differentiate into any type of plant cell- during the plant's entire life.
72
what can these stem cells be used to make?
clones of plants quickly and cheaply.
73
what can clones be made of?
- rare species- to prevent them being wiped out.
| - crop plants that have features useful for farmers.
74
what is diffusion?
diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.
75
how to simplify the definition of diffusion?
diffusion is the movement of particles from there being lot of them to where there are fewer of them.
76
where does diffusion happen?
solutions and gases.
77
an example of diffusion?
the smell of perfume DIFFUSES through the air in a room.
78
what is the difference in concentration called?
the concentration gradient.
| the bigger the difference in concentration teh faster the diffusion rate.
79
what will a higher temperature give and why?
a faster diffusion rate because the particles have more energy to move around faster.
80
what do cell membranes do?
they let stuff diffuse in and out of the cell.
81
what can fit through cell membranes?
only very small molecules can fit through cell membranes. (e.g: oxygen, glucose, amino acid and water).
82
what cannot fit through cell membranes?
big molecules like starch and protein.
83
where do the cells flow through from?
high concentration to lower concentration.
84
what is a net movement?
its an overall movement- if there are lots more particles on one side there is an net movement on that side.
85
what is the link with surface area and diffusion rate?
the larger the surface area of the membrane, the faster the diffusion rate. meaning more particles can pass through at the same time.
86
what is osmosis?
it is the movement of water molecules across a partially permeable membrane from a less concentrated solution to a more concentrated solution.
87
what is a partially permeable membrane?
it is one with very small holes in it.
88
what can pass through partially permeable molecules?
tiny molecules like water can but bigger molecules like sucrose can't.
89
what can water molecules do during osmosis?
water molecules can pass both ways through the membrane during osmosis.
90
what happens during osmosis?
water molecules move from the less concentrated solution to the more concentrated solution.
91
what does moving to a higher concentration mean?
the more concentrated solution gets more dilute.
92
what does the water act like during osmosis?
like it is trying to "even up" the concentration on either side of the membrane.
93
what is active transport?
sometimes substances need to be absorbed from a lower concentration to a higher concentration - against the concentration gradient. this is the process.
94
what do root hairs take in?
minerals and water.
95
what are plant roots covered with?
millions of of root hair cells.
96
where do the root hair stick out of?
they stick out into the soil.
97
what do the hairs give?
the 'hairs' give the roots a large surface area.
98
what are the hairs useful for?
for absorbing water and mineral ions from the soil.
99
why do plants need mineral ions?
for healthy growth.
100
how do root hairs take in minerals?
using active transport.
101
what is the concentration of minerals in root hair cells?
it is usually higher in the root hair cells than in the soil around them.
102
what can't root hair cells use?
they cant use diffusion to take up the minerals from the soil. so they use active transport instead.
103
what does active transport allow?
it allows the plant to absorb minerals from a very dilute solution in the soil. it moves the minerals against the concentration gradient.
104
what does active transport need?
it needs energy from respiration to make it work.
105
why do we need active transport?
to stop us from starving.
106
what does the body need to survive?
it needs to absorb nutrients from food to survive.
107
where does the nutrients in the body move from?
it moves from the gut into the blood.
108
what 's the concentration like in the body?
when there's a higher concentration of nutrients in the gut, they diffuse into the blood. sometimes there's a lower concentration of nutrients in the gut than there is in the blood.
109
what does active transport allow?
it allows the plant to absorb minerals from a very dilute solution in the soil. it moves the minerals against the concentration gradient.
110
what does having active transport allowed mean?
this means glucose can be taken into the blood against the concentration gradient. the glucose is then transported to cells where it's used for respiration.
111
why do we need active transport?
to stop us from starving.
112
what does the body need to survive?
it needs to absorb nutrients from food to survive.
113
where does the nutrients move from?
it moves from the gut into the blood.
114
what 's the concentration like?
when there's a higher concentration of nutrients in the gut, they diffuse into the blood. sometimes there's a lower concentration of nutrients in the gut than there is in the blood.
115
what is exchanging substances?
how easily stuff moves between an organism and its environment depends on its surface area to volume ratio.
116
what do organisms exchange substances with?
their environment.
117
what can cells use to get rid of waster products ?
they use diffusion.
118
what waste products can diffusion get rid of?
- carbon dioxide (from respiration).
- urea (from the breakdown of proteins) - urea diffuses from cells into the blood plasma. it is then removed from the body the kidneys.
119
how can you calculate an organism's surface area to volume ratio?
work out:
-surface area
-volume
use the number to work out the surface area to volume ratio.
120
how can you calculate an organism's surface area to volume ratio?
surface area- length x width
121
what's the link between organism and surface area and volume?
the larger the organism, the smaller its surface are is compared to it volume.
122
what's the link between surface area compared to its volume and the organism to exchange substances?
the smaller its surface area compared to its volume, the harder it is for an organism to exchange substances with its environment.
123
what does the human body have for diffusion to make sure that we can take in enough substances?
special surfaces.
124
what do multicellular organisms need?
exchange surfaces.
125
what do single-celled organisms have?
they have large surface area compared to their volume.
126
what does having a larger surface are compared to their volume mean?
they can exchange all the substances they need across their surface (the cell membrane).
127
what do multicellular organisms have?
they have a smaller surface area compared to their volume. (e.g: animals).
128
what does having a smaller surface area compared to their volume mean?
they can't normally exchange enough substances across their outside surface alone.
129
instead, mutlicellular organisms...
have specialised exchange surfaces.
130
what do multicellular organisms also have?
transport systems. this carries substances to and from their exchange surfaces.
131
what are their characteristics?
- thin membrane- so substances only have a short distance to diffuse.
- large surface area- lots of substance can diffuse at once.
- exchanging substances in animals have lots of blood vessels- stuff can get into and out of the blood quickly.
- gas exchange surfaces in animals (e.g: alveoli) are ventilated too- air moves in and out.
132
where does gas exchange happen?
in lungs.
133
what are exchanged in the lung?
- oxygen (o2)
| - carbon dioxide (CO2)
134
what do the lungs contain?
it contains millions of little air sacs called alveoli- it where gas exchange happen.
135
what are alveoli speialised for?
for diffusion of oxygen and carbon dioxide.
136
what do alveoli have?
- a large surface area.
- very thin walls (so gases don't have far to diffuse).
- a good blood supply.
137
what do the villi provide?
a really big surface area.
138
what is the inside of the small intestine covered with?
covered in millions of villi.
139
why do villi increase the surface area?
so that digested food is absorbed more quickly into the blood.
140
what do villi have?
- a single layer of surface cells.
| - a very good blood supply.
141
the structure of leaves lets gases do what?
diffuse in and out of cells.
142
what do plant leaves need?
to take in carbon dioxide for photosynthesis, and get rid of oxygen and water vapour.
143
what is underneath of the leaf?
an exchange surface and covered in small
| holes called stomata.
144
what diffuses through the stomata into the leaf?
carbon dioxide.
145
what diffuses out through the stomata?
oxygen and water vapour.
146
the size of the stomata are controlled by what?
guard cells.
147
what does the flattened shape of the leaf increase?
it increases the area of the exchange surface.
148
the walls of the cells inside the leaf are another what?
exchanging surface.
149
how does the gases diffuse?
they diffuse into and out of the cells through these walls.
150
what do gills have for gas exchange?
a large surface area.
151
what are the gas exchange surface in fish?
gills.
152
the plates have a lot of what?
blood capillaries- means they will have a good blood supply to speed up diffusion.
153
what happens in the gills?
oxygen diffuses from the water and into the blood. Carbon dioxide diffuses from the blood and into the water.
154
what are the gills made of?
lots of thin plates- which gives them a large surface area for gases to be exchanged.
155
the plates have a lot of what?
blood capillaries- means they will have a good blood supply to speed up diffusin.
156
why do they have a thin layer of surface cells?
so the gasses only have to diffuse a short distance.
