1.1 Flashcards
(87 cards)
1
Q
How was the development of the cell theory made possible
A
due to advances in microscopy
2
Q
Rules of the cell theory:
A
- living organisms are composed of cells
- cells are the smallest units of life
- cells come from pre-existing cells
3
Q
Name three examples of atypical cells
A
Striated muscle cell
Giant algae
Aseptate fungal hyphae
4
Q
How is striated muscle cell an atypical cell
A
it is composed of repeated units of sarcomeres, with striated pattern, it is multinucleate, it is also larger than a typical cell (30mm long)
5
Q
How is Giant algae an example of an atypical cell
A
It it very large 0.5 to 10cm in length
Asingle - celled organisms, challenges the fact that it should be simple in structure and small in size
6
Q
How does Aseptate fungal hyphae challenge the cell theory
A
it has no dividing walls (septa) which results in shared cytoplasm and multiple nuclei. Challenging the idea that a cell is a single unit
7
Q
what is the typical size of an animal cell
A
10 - 20 micro meters in diameters
8
Q
calculation of magnification
A
Magnification = Image size / actual
9
Q
1000 nm in micrometres
A
1 micro metre
10
Q
1000 micro meters in mm
A
1 millimetre
11
Q
around how much can the naked eye see in terms of size
A
just less than one mm
12
Q
around how small can the light microscope view
A
around 100 nanometres
13
Q
around how small can the electron microscope view
A
around 0.1 nm
14
Q
what is the size of an atom
A
around 0.1 nm
15
Q
around what size is a protein
A
between 1 and 10 nm
16
Q
around what size is a virus
A
between 10 and 100 nm
17
Q
around what size is mitochondria
A
between 100 nm and 1 micro meter
18
Q
around what size is a prokaryote cell
A
around 1 micro metre
19
Q
around what size is a eukaryotic cell
A
between 10 and 100 micro meters
20
Q
name in order the size of cells (smallest to largest)
A
Atom, protein , virus, mitochondria, prokaryote cell, eukaryote cell
21
Q
what cells can a light microscope not see
A
virus, protein, atom
22
Q
examples of unicellular organisms
A
bacteria, protozoa, archaea, fungi
23
Q
what are the seven life functions
A
Metabolism Response Growth Reproduction homeostasis excretion nutrition
24
Q
what is metabolism
A
the regular set of life-supporting chemical reactions that take place within the cell
25
what is growth
an increase in size or shape that occurs over a period of time
26
what is response
a reaction by the living organisms due to changes in the external environment (stimulus)
27
what is homeostasis
the maintenance of a constant internal environment by regulating internal cell conditions
28
what is nutrition
the intake of nutrients, which may take different forms in different organisms, can be heterotrophic ro autotrophic
29
what is reproduction
the production of an offspring either asexually or sexually to pass on genetic information to the next generation
30
what is excretion
the removal of wast products of metabolism and other unimportant materials from an organism
31
what is an example of a non-living cell
a virus - it cannot carry out all the processes of life, it has a protein coat and has genetic material however can not metabolism or reproduce
32
`two examples of a unicellular organism
Paramecium and chlamydomonas
33
What is a paramecium
a genus of unicellular protozoa, usually less than 0.25 mm in s`ie
heterotrophs feeding on food particles
has cilia, small hair like structures to propel the cell in a given direction
34
Wet is a chlamydomonas
a genus of unicellular green algae around 10 to 30 micrometer in diameter
has flagella to swim and an eye spot to detect light
they are autotrophs and can manufacture their own food
35
How do paramecium and chlamydomonas metabolism
Most metabolic reactions are catalysed by enzymes and take place in the cytoplasm.
36
How do paramecium and chlamydomonas grow
As it consumes food, the Paramecium enlarges. Once it reaches a certain size it will divide into two daughter cells.
Chlamydomonas - Production of organic molecules during photosynthesis and absorption of minerals causes the organism to increase in size. Once it reaches a certain size it will divide into two daughter cells.
37
How do paramecium and chlamydomonas respond
The wave action of the beating cilia helps to propel Paramecium in response to changes in the environment, e.g. towards warmer water and away from cool temperatures.
Chlamydomonas senses light changes in its environment using its eye spot and then uses its flagella to move towards a brighter region to increase the rate of photosynthesis.
38
How do paramecium and chlamydomonas homeostasis
A constant internal environment is maintained by collecting excess water in the contractile vacuoles and then expelling it through the plasma membrane. This process is called osmoregulation and helps Paramecium and Chlamydomonas to maintain their water balance.
39
Nutrition - paramecium and chlamydomonas
Paramecium is a heterotroph. It engulfs food particles in vacuoles where digestion takes place. The soluble products are then absorbed into the cytoplasm of the cell. It feeds on microorganisms, such as bacteria, algae and yeasts.
Chlamydomonas is an autotroph; it uses its large chloroplast to carry out photosynthesis to produce its own food.
40
reproduction - paramecium and chlamydomonas
It can carry out both sexual and asexual reproduction, though the latter is more common. The cell divides into two daughter cells in a process called binary fission (asexual reproduction).
It can carry out both sexual and asexual reproduction. When Chlamydomonas reaches a certain size, each cell reproduces, either by binary fission or sexual reproduction.
41
Excretion - paramecium and chlamydomonas
Digested nutrients from the food vacuoles pass into the cytoplasm, and the vacuole shrinks. When the vacuole, with its fully digested contents, reaches the Paramecium's anal pore, it ruptures, expelling its waste contents to the environment.
It uses the whole surface of its plasma membrane to excrete its waste products.
42
What is a heterotroph
an organism that feeds by taking in organic substances
43
what is an autotroph
an organism that can produce its own food from organic sources
44
what happens to SA:V ratio as the volume increases
SA: V decreases as the volume increases
45
what is the effect of a larger surface area to volume ration in a cell
heat loss occurs more quickly
and
faster exchange of waste materials
46
what is differentiation
the process by which unspecialized cells develop into cells with more distinct structures and function
47
what are emergent properties
means the whole organisms can do more things than the individuals cells are capable of because of their interactions
48
what is a genome
the complete set of genes
49
how many genes does the human genome consist of
around 21,000 genes
50
how do cells differentiate in multicellular organisms
they express some of their genes some of the time but not others
51
what is a stem cell
an undifferentiated cell of a multicellular organisms that can form more cells of the same type indefinitely and from which certain other kinds of cells arise by differentiation
52
what do stem cells do
they retain the capacity to divide indefinitely and have the potential to differentiate into specialized cell types when given the right stimulus
53
what are the four types of stem cells
totipotent stem cells
pluripotent stem cells
multipotent stem cells
unipotent stem cells
54
what can totipotent stem cells do
can divide into any type of cell including placental cells
can give rise to an entire/complete organism
55
what can pluripotent stem cells do
they can differentiate into all body cells but cannot give rise to a whole organism
56
what can multipoint stem cells do
can differentiate into a few closely related types of body cells
57
what can unipotent stem cells to
can only differentiate into their associated cell type
58
example of a totipotent stem cell
eight cells of the morula
59
example of pluripotent stem cells
embryonic stem cells of the blastocyst
60
example of multipotent stem cells
umbilical cord
61
example of unipotent stem cells
liver stem cells only make liver cells
62
use of human stem cells
muscle cells
nerve cells
blood cells
liver cells
bone cells
skin cells
63
What is stargardts disease
an inherited form of juvenile macular degeneration that affects the centre of the retina causing progressive loss of vision.
it is a recessive genetic mutation
64
ho w are stem cells used to treat stargardts disease
patients are given new retina cells derived from human embryonic stem cells which are injected into the retina
65
what is leukemia
cancer of the blood or bone marrow, caused by high levels of abnormal white blood cells
people with leukemia have a high risk of developing infections, anemia and bleeding
66
how are stem cells used to treat leukemia
involves harvesting hematopoietic stem cells (HSCs) that can be taken from bone marrow or the umbilical cord .
the patient then undergoes chemotherapy to get rid of the diseased white blood cells and the next step involves transplanting the HSCs back into the bone marrow so that they can differentiate to form healthy white blood cells.
67
what can stem cells be used for
cell therapy
transplants
harvested from the embryo at early stage, no pain is felt
68
Eukaryotic cells have intracellular and extracellular components. State the functions of one named extracellular component. 4 marks
plant cell wall - maintains shapes, strengthens and supports the plant ,prevents it from bursting in hypotonic medium
allows for turgor pressure
69
what is turgor pressure
Pressure exerted by fluid in a cell that presses the cell membrane against the cell wall.
70
Explain how the surface are to volume ratio influences cell sizes. 3 marks
SA limits the size of the cell as it needs to be large enough for nutrients and gases to be absorbed and large enough to excrete waste products
Volume limits size it determines the need for nutrients and as well as a cell grows, it divides when it reaches a certain stage
71
Outline differentiation of cells in a multicellular organism. 4 marks
Differentiation is the process by which unspecialized cells develop into more distinct structures and functions.
many types of cells that can differentiate
71
Outline differentiation of cells in a multicellular organism. 4 marks
Differentiation is the process by which unspecialized cells develop into more distinct structures and functions.
many types of cells that can differentiate
such as in epithelial cells, microvilli has finger like projection that help increase the surface area for absorption
72
Describe the importance of stem cells in differentiation. 3 marks
stem cells are undifferentiated cells
they can specialize into all sorts of cells
involves the expression of some genes but not others
embryo cells are examples of stem cells
stem cells can be used to heal, repair and replace tissues
73
Describe how Pasteur’s experiments provided convincing evidence to falsify the concept of spontaneous generation.
a. spontaneous generation is life appearing from nothing / from non-living / cells only come from pre-existing cells/life
b. broth/culture medium (for bacteria) (used/placed) in flasks
c. broth boiled/sterilized «in some flasks» to kill microbes
d. no clouding/signs of bacterial growth/reproduction / microbes did not appear «in flasks of boiled broth»
Allow bacteria or organisms instead of microbes.
e. after necks of flasks were snapped boiled broth became cloudy/growth of microbes
f. because microbes from the air contaminated the «boiled» broth
g. curved necks allowed indirect exposure to air but prevented entry of microbes
74
Discuss the advantages and disadvantages of the use of adult stem cells.
Markscheme
Advantages:
a. «adult stem cells» can divide «endlessly» / can differentiate
b. «adult stem cells» can be used to repair/regenerate «tissues»
c. fewer ethical objections «than with embryonic stem cells»
d. adults can give «informed» consent for use of their stem cells
e. adult source is not killed / «source» would not have grown into new human / no death of embryos used to provide stem cells
f. no rejection problems / patient’s own cells used
g. less chance of cancer/«malignant» tumor development «than from embryonic stem cells»
h. most tissues in adults contain some stem cells
Disadvantages:
i. difficult to obtain/collect/find in adult body/very few available
j. some «adult» tissues contain few/no stem cells
k. «adult stem cells» differentiate into fewer cell types «than embryonic cell
75
Outline the use of human embryonic stem cells (hESC) to treat Stargardt’s disease.
a. «an inherited form of» degeneration of retinal layer/photoreceptor cells/blindness
OR
eye genetic disorder
OWTTE
b. «hESC/stem cells» can provide/differentiate into healthy retinal cells
c. injecting «hESC/stem cells» into the retina/eye can restore vision in animal/human trials
76
Outline the properties of water molecules that permit them to move upwards in plants
a. water molecules are polar
OR
can form hydrogen bonds
b. cohesion between water molecules allows continuous water columns
OR
cohesion between water molecules allows transpiration stream «to form in xylem»
c. adhesion of water to the walls of xylem vessel «helps water rise»
d. water evaporates at environmental temperatures allowing transpiration pull
77
Define osmolarity.
the measurement of solute concentration fo a solute
78
Outline the effectiveness of antibiotics against viruses and bacteria.
effective against bacteria but not viruses
79
State one role of saprotrophic organisms in the ecosystem.
recycle nutrients, decomposer
80
```
The onion (Allium cepa) is an angiospermophyte. The honey bee (Apis mellifera) is an arthropod. State three structural differences[2 marks]
between the cells of an onion and a honey bee.
```
onion:
cell wall
no centrioles
chloroplasts
fixed shape
```
honey bee:
no cell wall
centrioles
no chloroplasts
not a fixed shape
```
81
State what is indicated by the presence of polysomes in a cell.
much protein of one type needed/produced by polysomes;
| mRNA is being repeatedly translated;
82
Discuss the evidence supporting the endosymbiotic theory for the origin of eukaryotes.
a. chloroplasts, mitochondria and prokaryotes are a similar size;
b. all have 70S ribosomes;
c. double membrane suggests engulfing by endocytosis;
d. all contain naked DNA;
e. all divide by binary fission;
f. chloroplasts and mitochondria cannot survive on their own;
g. theory cannot be repeated/falsified;
83
Outline the cell theory
a. living things are composed of cells;
b. cells are the basic/smallest unit of life;
c. cells come from pre-existing cells;
84
Discuss the endosymbiotic theory including the evidence for the process shown in the diagram.
a. ancestral eukaryote cell engulfs free living prokaryote;
b. free living prokaryote not digested;
c. symbiotic relationship develops between ancestral eukaryote cell and engulfed prokaryote;
d. ancestral eukaryote cell and engulfed prokaryote reproduce as a unit;
e. the engulfed prokaryote provides energy by aerobic respiration for the eukaryote;
f. prokaryote gains protection/nutrition;
g. organelles have double membranes;
h. organelles have DNA/ribosomes;
i. theory cannot be falsified/tested;
85
Discuss the endosymbiotic theory for the origin of eukaryotes.
a. microorganisms/prokaryotes taken into cell by endocytosis;
b. kept inside cell and perform respiration/photosynthesis;
c. developing into mitochondria/chloroplasts;
d. mitochondria/chloroplasts have double membranes (as expected in cells taken in by endocytosis);
e. mitochondria/chloroplasts have (circular naked) DNA (as prokaryotes);
f. mitochondria/chloroplasts have 70S ribosomes (as prokaryotes);
g. mitochondria/chloroplasts grow and divide like (prokaryotic) cells;
86
Animal cells often secrete glycoproteins as extracellular components. What is a role of these glycoproteins?
for adhesion
