Science - Term 1 + 1st half Flashcards
1
Q
What are living organisms made of?
A
Cells
2
Q
What are cells?
A
- The smallest units found in an organism.
3
Q
What is a unicellular organism?
A
Organisms such as bacteria that are made of one cell.
4
Q
What is a multi-cellular organism?
A
Millions of cells can join together to form a person.
5
Q
When were cells first seen?
A
350 year ago by Robert Hooke
6
Q
What was Robert Hooke and what did he do?
A
He as a scientist. He looked down a microscope at a thin slick of cork.
7
Q
What did Robert Hooke see when he looked through a microscope?
A
Tiny room like structures, he called cells.
8
Q
What is cork?
A
A plant cell from a tree bark.
9
Q
What is an observation?
A
Looking carefully and in detail at an object.
10
Q
How do you look at a very small object in detail?
A
A microscope
11
Q
State what all living organisms are made up of?
A
Cells
12
Q
Write down what Robert Hooke saw when he looked at cork using a microscope?
A
Tiny room like structures he called cells.
13
Q
State what is meant by a scientific observation?
A
Looking carefully and in detail at an object.
14
Q
The steps to observing a microscope are…
A
… 1. Move the stage to its lowest position.
2. Place the object you want to observe on the stage.
3. Select the objective lens with the lowest magnification.
4. Look through the eyepiece and turn the coarse-focus knob slowly until you see the object.
5. Turn the fine-focus knob until your object comes into focus.
6. Repeat Steps 1 to 5 using an objective lens with higher magnification to see the object in greater detail.
15
Q
The magnification formula
A
Eyepiece lens magnification x Objective lens magnification = Total magnification
16
Q
Components of an animal cell =
A
A nucleus, cell membrane, cytoplasm and many mitochondria.
17
Q
Cytoplasm =
A
This is a ‘jelly-like’ substance where the chemical reactions in a cell take place.
18
Q
Cell membrane =
A
This is a barrier around the cell. It controls what can come in and out of the cell.
19
Q
Nucleus =
A
This controls the cell and contains genetic material. Genetic information is needed to make new cells.
20
Q
Mitochondria =
A
This is where respiration happens. Respiration is a reaction that transfers energy for the organism.
21
Q
Name the four key components found in an animal cell?
A
- Nucleus
- Cytoplasm
- Mitochondria
- Cell membrane
22
Q
State the function of the cell nucleus?
A
Controls the cell and contains the genetic material. The genetic information is need to make new cells.
23
Q
Name the part of the microscope that we look through?
A
The eyepiece lens.
24
Q
What is specific to plant cells?
A
- Cell wall
- Vacuole
- Chloroplasts
25
Cell wall =
This strengthens the cell and provides support . It is made of tough fibre called cellulose, which makes the wall rigid.
26
Vacuole (normally permanent) =
This contains a watery liquid called cell sap.
27
Chloroplasts =
This is where photosynthesis happens, Chloroplast contain a green substance called chlorophyll, which traps energy transferred from the sun.
28
Name the cell components that are only found in plant cells?
- Cell wall
- Vacuole
- Chloroplasts
29
What is found inside the vacuole?
A watery liquid called cell sap.
30
How do animal cells differ?
They are changes so that they are suited to carry out a particular job.
31
The differences between different cell types is...
... structureal adaptations.
32
Specialised cells =
Cells that have been adapted to carry out a particular job.
33
Nerve cell =
A cell that carries electrical impulses around the body
34
What are the adaptations of a nerve cell?
Are long and thin and have connections at each end where they join to other nerve cells = Allows them to transmit messages around the body.
35
Red blood cell =
A cell the transports oxygen around the body.
36
What are the adaptations of a red blood cell?
Contain haemoglobin = Join oxygen.
Have no nucleus = Increase space for haemoglobin.
Disc shaped = Increase their surface area for carrying oxygen.
37
State the function of the nerve cell?
To transmit messages around the body.
38
Name the component, normally found in animal cells that is missing in a red blood cell?
Nucleus
39
What is a specialised cell?
A cell that is adapted to do a certain job.
40
Sperm cell =
A cell that is specialised to carry male genetic material.
41
What are the adaptions of a sperm cell =
Streamlined head and long tails = Help the cell to move through a liquid.
Lots of mitochondria = Transfer energy
Acrosome at the front = Digest its way through the egg cells membrane
Haploid nucleus = To form a diploid nucleus when combined with a egg cell
42
Sperm Cell + Egg Cell -------->
--------> the head of the sperm burrows into the egg.
43
Leaf cells =
They are cells found near the top of a leaf that carry out photosynthesis.
44
What are the adaptations of a leaf cell =
Large surface area and lots of Chloroplasts = absorbs energy transferred by the Sun.
45
What is a the function of a root hair cell?
Absorb water and nutrients form the soil.
46
What are the adaptions of a root hair cell =
Large surface area = Absorb wate and nutrients.
No chloroplasts = Cells have no light to carry out photosynthesis.
47
Nucleus
This contains genetic material. The material is stored in chromosomes.
48
Diploid
A cell with 2 copies of each chromosome.
49
What happens to chromosomes in mitosis?
One parent chromosome comes form the organism's mother and one from the organism's father.
50
DNA
Chromosomes that are long lengths of a molecule.
51
Cell cycle
Body cells in multi cellular organism divide to produce new cells during this process.
52
Interphase
The start of the cell cycle. When a cell has been produced by cell division and ends with the cell divided to produce two identical cells.
It can be summarised as a stage of cell growth and DNA replication.
53
Mitosis
When a cell reproduced itself by splitting in two to form two genetically identical offspring.
The division of the nucleus
54
Cytokinesis
Takes place at the end of the cell cycle resulting in two new genetically identical diploid cells.
55
What are the 3 main phases of cell growth?
1) Interphase
2) Mitosis
3) Cytokinesis
56
What happens in interphase?
1. A cell that's not dividing the DNA is all spread out in long stings.
2. Before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
3. It then duplicates its DNA - so there's one copy of each chromosome for each new cell. The DNA is copied and forms X-shaped chromosomes. Each 'arm' of the chromosome is an exact duplicate of the other. Each 'arm' is called a chromatid.
57
What is the mnemonic of the phases of cell growth?
I = Interphase
Prefer = Prophase
Milk = Metaphase
And = Anaphase
Tasty = Telophase
Cookies = Cytokinesis
58
What are the phases of mitosis
1) Prophase
- The chromosomes condense, getting shorter and fatter.
- The membrane around the nucleus breaks down.
- The chromosomes lie free in the cytoplasm.
2) Metaphase
- The chromosomes line up at the centre of the cell.
3) Anaphase
- Spindle fibres pull the chromosomes apart.
- The two arms of each chromosome(chromatids) are pulled apart.
4) Telophase
- Membranes form round each of the sets of chromosomes.
- These become the nuclei of the two new cell (the nucleus is divided).
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What happens in cytokinesis?
The cytoplasm and the cell membrane divides to form two separate cells.
60
Interphase ------------> Mitosis ------------> Cytokinesis------------>
------------> Two new daughter cell are produced. Each daughter cell contains exactly the dame set of chromosomes in its nucleus - two cells are genetically identical. They're also genetically identical o the diploid parent cell. This makes the daughter cells diploid too.
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Uses of mitosis
- By multicellular organism to grow.
- By multicellular organisms to replace cell that have been damaged.
- By some organisms to reproduce by asexual reproduction.
62
Calculating the number of cell =
2^n
n = Number of divisions by mitosis.
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Prokaryotic
- Small
- Simple
- Single celled
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Eukaryotic
- Complex
- Multicellular
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Nucleus
Contains genetic material that controls the activities of the ell. Genetic material is arranged into chromosomes.
66
Cytoplasm
A gel like substance where most of the chemical reactions happen.
It contains enzymes that control these chemical reactions.
67
Cell membrane
Holds the cell together.
Controls what goes in and out.
68
Mitochondria
These are where most of the reactions for aerobic respiration take place.
Respiration transfers energy that the cell needs to work.
69
Ribosomes
These are involved in protein synthesis. The second date of protein synthesis takes place here.
70
Protein synthesis
Making protein
71
Translation
The second stage of protein synthesis.
72
Cell wall
A rigid structure made of cellulose. I supports and strengthens the cell.
73
Large vacuole
Contain cell sap, A weak solution of sugar and salt. It maintains the internal pressure to support the cell.
74
Chloroplasts
These are where photosynthesis occurs and makes the food for the plant. It contains chlorophyll.
75
Chlorophyll.
Which absorbs the light needed for photosynthesis.
76
What type of cell is a bacteria cell?
Prokaryotic
77
What do bacteria cells not have one of?
One true nucleus
78
Plasmids
May only contain one or more small loops of DNA.
Plasmids contain genetics for things like drug resistance.
79
Flagellum
This is a long hair-like structure that rotates to make the bacterium move. It can be used to move the bacterium away from harmful substance like toxins and towards beneficial things like nutrients or oxygen.
80
Specialised cell
A cell that performs a specialised to perform a specific function.
81
Sperm cell + Egg cell --------->
---------> Fertilised egg cell
82
What are the adaptions of an egg cell?
Haploid nucleus = To form a diploid nucleus when combined with a egg cell and offspring then have the right amount of DNA.
83
Haploid
A nucleus with half the number of chromosomes that's in a normal body cell.
84
Ciliated epithelial cell
A cell that lines the surface of an organ. They have cilia of the top.
Their function is to move substance in one direction along the tissue.
85
What are the adaptions of a ciliated epithelia cell?
Cilia = Trap dust in the it. Move substance in one direction.
86
Microscope
Scientific instrument that let us see thing that we can't see with the naked eye.
87
Light Microscope
*It uses light and lens to form an image of a specimen and magnify it. * They let you see individual cells and larger subcellular structure like nuclei and chloroplasts. They can also be used to study living cells.
88
Electron microsocpes
*They use electrons instead of light to form an image. They have a much higher resolution than light microscopes. They also have a higher resolution.
They can *see much smaller things in more detail* like the internal structure of mitochondria and chloroplasts. They even let us see tinier things like ribosomes and plasmids. This has given us a greater understanding of how cells work and
89
How do you prepare a slide?
1) Add a drop of water to the middle of a clean slide. This will secure the specimen in place.
2) Cut a specimen and separate it out into layers.
3) Use tweezers, place the tissue into the water on the slide.
4) Add a drop of iodine solution. Iodine solution is a stain. Stains are used to add colour to objects in a cell making them easier to see. Different stains can be used to highlight different things.
90
How do you prepare a slide for a root hair cell so that you can see it during the process of mitosis?
1) Cut a specimen and separate it out into layers.
2) Use tweezers, place the tissue into hot acid
3) Add a drop of water to the middle of a clean slide. This will secure the specimen in place.
4) Use tweezers to place the tissue on to the slide.
5) Use the the flat ended tool to iron out any air bubbles that you have in the specimen.
6) Add a drop of iodine solution. Iodine solution is a stain. Stains are used to add colour to objects in a cell making them easier to see. Different stains can be used to highlight different things.
7) Place the coverslip over the specimen.
91
How do you observe the specimen?
1) Start by clipping the slid you've prepared onto the stage.
2) Select the lowest-powered objective lens (i.e. the one that produces the 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 know, until you get a clear image of what's on the slide.
6) If you need to see the slide with greater magnification, or swap to a higher-powered objective lens and refocus.
92
Drawing observations
When making a drwing of a your specimen form under the microsope make sure you use a pencil with a sharp point and that you can draw with clear unbroken lines. Your drawing should not include any colouring or shading if you are drawing cell, the subcellular structures shousl be drawn in proportion (the correct size relative to each other). If you're asked to make your drawing in a certain amount of space (e.g. a worksheet,) it needs to take up at least half the space available.
93
Magnification formula
Eyepiece lens magnification X Objective lens magnification = Total magnification
94
To find the magnification you need to...
image size/ real size
95
Cell division
This happens by mitosis.
96
Cell differentiation
Cells differentiation is the process by which cells change to become specialised for its job. Having specialised cells allows multicellular organisms to work more efficiently because different types can carry out different functions.
97
Cell elongation
This is where a plant cell expands making the cell bigger and so making the plant grow.
98
Growth in animals
All growth in animal happens by cell division. Animals ten to grow they're young and then reach gull growth and stop growing. So when you're young, cell divide at a fast rate but once you're an adult, most cell division is for repair - the cells divide to replace old or damaged cells. This also meant that, in most animals, cell differentiation is lots at an early age.
99
Resolution
The quality of the image that you see.
100
Growth in plants
In plants, growth is mainly due to cell elongation. Cell division usually just happen in the tips of the toots and shoots. But plant often grow continuously - even really old trees will keep putting out new branches. So, plants continue to differentiate to develop new parts, e.g. leaves, roots.
101
Meristems
The tips of the roots and shoots.
102
Cancer
The body controls the amount of cell division that happens for growth so cells will normally stop dividing when enough new cells have been produced. The rate at which cells divide by mitosis is controlled by the chemical instruction (genes) in an organism's DNA.
If there's a change in one of the genes that control the cell division, the cell may start dividing uncontrollable - growth doesn't stop. This can result in mass abnormal cells called a tumour.
103
Percentile Charts
Percentile charts can be used to assess a child's growth over time, so that an overall pattern in development can be seen and any problems highlighted,
104
Stem Cells
Cells that are undifferentiated. These undifferentiated cells are called stem cells. They can divide to produce into different types of cells, depending on what instructions they're given.
105
What are adult stem cells used for in medicine?
They are used to cure diseases.
106
Embryonic stem cells in medicine
Scientists have experimented with extracting stem cells form very early human embryos and growing them. Under certain conditions, stem cells can be stimulated to differentiate into specialised cells.
107
Embryonic stem cells in the future could...
... replace faulty cells in sick people.
108
Issues involved in using stem cells
- Ethical issues
- Some people are against it
- They feel that human embryos shouldn't be experimented on as they are a potential human life.
- However some think that curing live patient is more important the the rights of embryos
109
Where can stem cells in plant be found?
Tips of roots and shoots.
110
Sexual Reproduction
The reproduction where genetic information form two organisms is combined to produce offspring which are gametically different to either parent Sexual reproduction involves gametes.
111
Gamets
- Haploid cells
- In sexual reproduction the mother and father produce gametes by meiosis.
112
Fertilisation
When a male gamete fuses with he female gamete to produce a fertilised egg(also known as a zygote).
113
Zygote----------- ??? ------------> Embryo
Undergoes cell division
114
Meiosis
- A type of cell division
115
Why is meiosis different to mitosis?
Meiosis does not produce identical cells.
Meiosis produces cells which have half the normal number of chromosomes.
116
What is the process of cell division by meiosis?
1) Before the cell starts to divide it duplicates its genetic information, forming two armed chromosome - One arm of each chromosome is an exact copy of the other arm. After replication, the chromosomes arrange themselves into pairs.
2) In the first division in meiosis the chromosome pairs line up in the centre of the cell.
3) The pair are then pulled apart so each new cell only has one cop of each chromosome. Some of the father's chromosomes and some of the mother's chromosomes go into each new cell. This mixing up of their genes creating genetic variation the offspring.
4) In the second division, the chromosomes lined p again in the centre of the cell. The arms of the chromosomes (called chromatids) are pulled apart.
5) You get four haploid daughter cells - these are the gametes. Each gamete only has a single set of chromosomes in it. Each of the gametes (sperm or egg cells) is genetically different form the others.
117
Asexual Reproduction
It is reproduction involving only one parent. SO the offspring are genetically identical to the parent.
Happens by Mitosis.
An ordinary cell divides into two to make two of new cells.
118
Advantages of asexual reproduction
- Reproductive cycle is faster.
- Can reproduce offspring quickly.
- can reproduce whenever conditions are favourable.
- Doesn't have to wait for a mate.
- Able to colonise new areas very rapidly.
119
Disadvantages of asexual reproduction
- No genetic vairation.
- If conditions are unfavourable who population will not cope.
120
Advantages of sexual reproduction
- Offspring have a mixture of two set of DNA.
- Genetic variation.
- Increases chance of a species surviving changes in the environment.
- Survival advantage.
- Adapted to the environment.
- Lead to evolution.
- Able to breed sucessuflly.
121
Disadvantages of sexual reproduction
- Organisms need to find and attract mates.
- Takes more time.
- Takes more energy.
- Fewer offspring.
- Individual could be isolated.
122
DNA
- It stands for DEOXYRIBONUCLEIC ACID.
- It is the chemical which all the genetic material in a cell is made up from.
- It contains coded information - basically all the instructions to put an organism together and make it work.
- So it's what's in the DNA that determins what inherited characteristics you have.
- It is found in the nucleus of eukariotic cells in really long structures called chromosoems.
- The DNA is coiled up to form the 'arms' of the chromosomes.
- In diploid cell, chromosomes come in pairs.
- It is a polymer.
- It is made up of two strands twisted together int he shape of a doul helix.
123
Polymer
A large molecule built from a chain of smaller molecules.
124
Gene
A small section of DNA that codes for a specific protein.
125
Each gene codees for...
...a particular sequence of amino acids which are put together to make a specific protein.
126
Genome
All organims are made of them.
127
Alleles
- All genes exist in different versions.
- Gametes have one allele but all the other organism have two - one for each chromosome in a pair.
* This is because we inherit half of our alleles from our mother and half from our father.
- In diagrams letter generally represent alleles.
- They can either be homozygous or heterozygous.
- For an organism to display a recessive characteristic, both alleles must be recessive but to display a dominant characteristic the organism can either be CC or Cc.
* This is because the dominant allele overrules the recessive one if the plant/animal/other organism is heterozygous
128
Homozygous
Two alleles for one gene that are the same.
129
Heterozygous
Two alleles for one gene that are different.
130
How do you show dominant characteristics?
Capital letter
131
How do you show ressesive characteristics?
Lowercase letter
132
Genotype
Is the combination of alleles you have e.g. CC, cc or Cc.
133
Phenotype
It is the set of observable characteristics or traits of an organism.
134
Monohybrid Inheritance
This is where you cross two parent to look at just one characteristic. Characteristics that are determined by a single gene can be studied using monohybrid croses.
135
Genetic diagrams of monohybrid inheritance
- Genetic diagrams allow you to see how certain characteristics are inherited.
- The inheritance of round and wrinkly peas for pea plant is an example of monohybrid inheritance and can be shown using genetic diagrams.
- You need to to able to use genetic diagrams to predict and explain the outcomes of monohybrid crosses betweeen individuals for lots of different combinations of allels.
- The outcomes are given as ratios and can be workd out by the probability of having offspring with a certain characteristic.
136
Probability
How likely something is to happen.
137
A 3:1 ratio in the offspring
- A cross can produce a 3:1 ratio for a certain characteristic in the offspring.
138
All offspring are the same
More than one cross could result in all of the offspring showign the same characteristic.
139
A 1:1 ratio in the offspring
When a cross produces a 1:1 ratio in the offspring - half the offspring are likely to show one characteristic and half are likely to show another characteristic.
140
How to draw a punnett square?
1. First, draw a grid with four squares.
2. Put the possible alleles form one paent down the side and those form the other parent along the top.
3. Then in each middle square you fill in the letters from the top and side that line up with the that square - the pairs of letters in the middl show the possible combinations of alleles.
141
How to draw a genetic diagram?
1. Draw two circles at the top of the diagram to represent the parents. Put the round genotype in one and the wrinkly genotype in the other.
2. Draw two circle below each of the parent circle to represent the possible gamets. Put a single allele from each parent in each cirlce.
3. One gamete from the female combines with one gamete from the male during fertilisation, so draw criss-cross lines to show all the possible ways the alleles could combine.
4. Then write the possible combinations of alleles in the offspring in the bottom cells.
142
Family Pedigrees
A diagram that shows hows a characteristic (or diorder) is inherited in a group of related people.
143
Gregor Mendel
An Austrian mond who trianed in mathermatics and natural hisotry at the university of Vienna
144
What did Gregory Mendel do?
On the garden plot at the monastery, Mendel noted characteristics in plants were passed on from one generation to the next. The results of his research were published in 1866 and eventually becaome the foundation of modern genetics.
145
# Generation 1
Mendel's work
Mendel did lots of experiments with pea plants. In one experiment he crossed two pea plants of different heights - tall pea plant and a dwarf pea plant. The offspring were all tall pea plants.
146
# Generation 2
Mendel's work.
After a generation of tall pea plant he bread 2 of them and got some tall and some short pea plants.
| Tecnically it was 3 tall pea plants and 1 dwarf pea plant.
147
What did Mendel's results show
It can be explained using genetic diagrams, where T is the hereditary unit for tall plant and t is the heridatiry unit for dwarf plants.
148
# First cross
Mendel's results
The first cross result in plant that are Tt. so they are tall plants but they carry the herideitary unit for dwarf plants.
149
# Seoond cross
Mendel's results
The next generation have either got TT, Tt or tt. This is becuase they either carry the tall genes from both the parents. However some carry the dwarf genes form both the parents. As well as some carry the tall gene form one parent and the dwarf gene from the other.
150
151
Mendel's conclusion
1) Characteristics in plants ar edetermined by "hereditary units".
2) Hereditary units are passed on to offspring unchnaged form both parents, one unit form each parent.
3) Hereditary units can be dominant or recessive - if an individual has both the dominant and the recessive unit fo ra characteristic, the dominant characteristic will we expressed.
152
The importance of Mendel's work
We now know tha the "hereditary units" are of course gene. But Mendel's work waa cutting edge and new to the scientists of the day. They didn't have the background knowledge to properly understand his findings - they had no idea about genes, DNA and chromosomes.
It wasn't until after his death that people realised how significant his work was and that the mechanism of inheritance could be fully explained.
153
Mapping of the human genome
Thousand of scientis from all over the world collaborated on the Human Genome Project. The big idea was to find every single human gene. The project officially started in around 1990 and a complete map of the human genome, including the location of aroudn 20 500 genes, was completed in around 2003.
Now that the genes have all been found scientists are trying to figure out what they all do. So far, the project has helped to identify about 1800 genes related to diseases, whihc has huge potential benefits for medicine.
154
Collaberated
Worked together
155
Medical applications of the human genome project
1) Prediction and prevention of diseases
2) Testing and treatment for inherited disorders
3) New and better medicines
156
# The Human Genome Project - Medical Applications
Prediction and prevention of diseases
Many common disease like caners and heart diseases are caused by the interaction of different genes, as well as lifestyle factors. If doctors knew what allels predisposed people to what diseases, we could all get individually tailored advice on the best diet and lifestyle to avoid outr likely problems. Doctors could also check us regularly to ensure early treatment if we do develop the diseases we're susceptible to. This could increas chance of a full recovery.
157
# The Human Genome Project - Medical Applications
Testing and Treatment for inherited disorders
Inherited disorders (e.g. cystic fibrosis) are caused by the presence of one or morefauly allels in a person's genome. Thanks to the Human Genome Project, scientists are now able to identify the genes and alleles the are suspected to causing an inherited diorder much more quickly tha they could do in th epast. Once an allele that causes an inherited disorder has been identified, people can be tested for it and it may be possible to develop better treatments or even (eventually) a cure for the disease.
158
# The Human Genome Project - Medical Application
New and better medicines
Some allels affect how our individul bodies will react to certain diseasea and to the possilbe treatments of them. Scientists can use this knowledge to design new drugs that are specifically tailored to people with a certain allel. The can also determine how well an existing drug will work for an individual. Generic tests can also hep dermine what dosage is most appropriate for particular drugs in different patients.
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