Science Semester 1 Flashcards
(154 cards)
1
Q
What is the nucleus?
A
It is a small and very dense particle, consisting of protons and neutrons, which are held together by a very large nuclear force. The nucleus makes up almost all of the mass of an atom.
2
Q
What are protons?
A
Protons are particles which have a positive electric charge.
3
Q
What are neutrons?
A
They share the same mass as protons, and have no electric charge.
4
Q
What is an electron?
A
Electrons orbit the Nucleus. Electrons have a negative electric charge.
5
Q
In symbols, isotopes are represented as A/Z E, where:
A
A = The mass number; the sum of protons and neutrons in nucleus. Z = The atomic number; the number of protons in the nucleus E = Chemical symbol.
6
Q
All atoms of a particular element have the same number…
A
Of protons.
7
Q
How did Lord Rutherford find out that the atoms in solid gold are mostly empty space?
A
Lord Rutherford’s atom model was based on experiments in which he fired time positive alpha particles at very thin sheets of gold foil. Most particles went straight through the sheet, where the rest were reflected by a small, positively-charged nucleus. Most atoms carried through because it was empty space.
8
Q
The number of neutrons in atoms of the same element is different, because such atoms have the same numbers but different mass numbers. Atoms of the same element with different mass numbers are called
A
Isotopes.
9
Q
In most atoms, the protons and neutrons found in the nucleus are held together very strongly. The nuclei of these atoms are said to be
A
Stable.
10
Q
If neutrons and protons are not held together strongly, the nuclei is therefore
A
Unstable
11
Q
Isotopes that are unstable decay to form other elements. These isotopes are said to be
A
Radioactive, and are called radioisotopes.
12
Q
Isotopes that ustable are
A
Radioisotopes.
13
Q
Natural radioactivity is
A
Radioactivity emitted from matter without energy being supplied to atoms. There’s 50 isotopes that emit radioactivity naturally,many exist in air, water, and living things in the ground.
14
Q
Most radioactive isotopes (about 2,000 in total) are made radioactive artificially by
A
Bombarding their atoms with protons and neutrons.
15
Q
Energy emitted by radioactive substances is called
A
Nuclear radiation, because it comes from the nucleus.
16
Q
Alpha particles are
A
Helium nuclei that contain two protons and two neutrons, Alpja particles a
Are positive,y charged. They cannot travel easily through materials and can be stopped by a sheet of paper or human skin. Cannot damage outside, but if inhaled, can cause serious damage.
17
Q
Beta particles are
A
The same side and mass of electrons, and can have a negative or positive electric charge and can travel at speeds as high as 99% of the speed of light. Beta particles can penetrate human skin and can damage living tissue, but they cannot penetrate thin layers of plastic, wood or aluminium.
18
Q
Gamma rays are
A
BURSTS OF energy released after alpha or beta particles are emitted. Gamma rays travel at the speed of light and are highly penetrating. They can cause serious and permanent damage to living tissues and can stopped only be a thick shield of lead or concrete.
19
Q
The nuclei of different radioactive substances decay at different rates, Some radioisitopes decay in a few seconds, while others take thousands of years. The time taken for half of all the nuclei in a sample of a radioisotope to disintegrate of decay is known as its
A
Half-life.
20
Q
There are 3 naturally occurring isotopes of uranium; uranium-238, uranium-235 and uranium-234. Each of the isotopes spontaneously decay spy. Producing alpha particles and gamma rays. Half-lives can vary from milliseconds to billions of years. The half-live of each of the uranium isotopes are more than a billion years. If isotopes have 1 half life, it has 1/2 of its life remaining. 2=1/4, 3=1/8…
A
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21
Q
Clearly describe the use of radioisotopes in radiometric dating.
A
Geologists make use of radioisotopes to determine the age of rocks and fossils. This technique is called radiometric dating.
22
Q
Clearly describe the use of radioisotopes in nuclear power.
A
For example, uranium is converted to uranium dioxide, and then sealed in fuel rods. The uranium undergoes a fission reaction on the reactor when neutrals are fired at the radioactive uranium, causing the uranium nuclei to split and form 2 new elements, releasing heat energy. This energy boils water to convert water to steam.
23
Q
Clearly describe the use of radioisotopes in the treatment of cancer.
A
There are 2 ways.
External Radiotherapy, which involves radiation being directed at the cite of cancer by a linear accelerator, This is the name of machines used to deliver radiation at the source of cancer.
Brachytherapy (internal radiotherapy) involves placing isotopes inside the body at the cite of cancer.
24
Q
Clearly describe the use of radioisotopes in the diagnosis of diseases.
A
Radioactive substances may be injected into the body to detect or identify the cause of disease, some radioisotopes can be used to obtain images. Gamma rays emitted by these radioisotopes produce these images, PET scans (Pesitra, Emission Tomography) use cameras surrounding the patient to detect gamma rays coming from radioisotopes injected into the body.
25
What causes radioactivity?
Naturally, where radioactivity is emitted from matter without energy being supplied to its atoms.
Most radioactive isotopes are made radioactive artificially by bombarding their atoms with sub-atomic particles like protons and neutrons.
26
Clearly describe the use of radioisotopes in preserving food.
Food in sealed containers can be preserved by exposing it to gamma radiation. This radiation kills the micro-organism in the food and keeps it from spoiling.
27
How do chemical reactions take place?
Chemical reactions take place when the bonds between atoms are broken and new bonds are formed, creating a new arrangement of atoms and atleast 1 new substance.
28
What are some observable changes to show a chemical reaction has taken place?
Change in colour, formation of gases (which can be seen)m or a new solid, or perhaps even just an odour.
29
What is the Law of Conservation of Mass?
A law which states that matter can't be destroyed or created during chemical reactions.
30
What is the Law of Constant Proportions?
A law chick states that a comlound, no matter how it's formed, always contains the same relative amount of each element.
31
The new substances that are formed during a chemical reaction are called:
Products.
32
The original substances before a chemical reaction takes place are called:
Reactants.
33
What possible sources of energy can be used to start a reaction?
Energy sources include electrical currents, beams of lights, flames.
34
What is an endothermic reaction?
Chemical reactions in which energy is absorbed from the surroundings. Endothermic reactions are cold from this.
35
What is an exothermic reaction?
A chemical reaction involving heat being created and sent outwards from the reaction place.
36
Who was Alfred Nobel, and what was he famous for?
Alfred Nobel was a chemist and physicist, who was famous for investing in dynamite, an explosive which released large amount of energy and gas, exerting great pressure.
37
Explain how an airbag works.
The rapid inflation I'd an airbag is the result of an explosive exothermic chemical reaction. The reaction is triggered by an electronic device in the car that detects any sudden change in speed or direction of the car. The bag fills with a harmless gas, and when the occupants move forwards or sideways into the bah, they push the gas out of the airbags through tiny holes in the nylon, The airbag is usually totally deflated by the time the car comes to rest.
38
Explain why the chemical process that takes place in an icepack containing ammonium chloride is not a chemical reaction.
Ammonium chloride + water -> Ammonium Chloride in solution. Although the chemical bonds are broken in this process, it's not a chemical reaction because no new substances are formed.
39
In the human brain, the cerebrum has key roles in what?
Thinking processes, such as having conscious thoughts, problem solving, decision making, memory, language, and learning.
40
In the human brain, the cerebral cortex is what?
The outside layer of tightly-packed neurons covering the celebrum.
41
The human brain, the cerebellum is responsible for what?
It is responsible for balance, coordinates movement, and has a role in speech, language, memory, and learning.
42
In the human brain, what does the brain stem do?
The brain stem (or medulla) regulates your life support systems, such as heart rates breathing, and blood pressure.
43
In the human brain, what is the frontal lobe responsible for?
Decision making, planning, working memory, and higher order thinking.
44
In the human brain, what is the temporal lobe responsible for?
Hearing, explicit memories, words, and pictures.
45
In the human brain, what is the parietal lobe responsible for?
Sensory information, motor functions, and spatial awareness.
46
In the human brain, what is the occipital lobe for?
Vision, pictures, colours, and movement.
47
What is Homeostasis?
Where the internal environment in which the cell lives needs to be kept constant. Temperature, pH, and concentrations of Ions, glucose, water and carbon dioxide need to be within a particular range.
48
What is the stimulus-response model?
Where receptors detect responses to create change to correct uneven conditions.
(Stimulus)->(Receptor)->(Control Centre)->(Effector)->(Response)
49
Define negative feedback reactions.
A response which goes in an opposite direction to the stimulus.
(BLOOD LEVELS TOO HIGH: Lower Blood Levels.)
(BLOOD LEVELS TOO LOW: Raise Blood Levels.)
50
What is Glucagon, Glycogen and Glucose?
If the receptor detects lack of blood levels, the hormone Glucagon is released. This breaks down glycogen to become glucose.
51
What is a positive feedback reaction?
Where the response goes in the same direction, and has a positive effect on the stimulus.
52
What does the Nervous System and Endocrine System do?
It involves the message being sent as a nervous or electrical impulse along a neutron and then as a chemical message (neurotransmitter) across the gaps (synapses) between them.
The endocrine system uses only chemical messages (hormones) transported throughout the circulatory system to its target cell.
53
What is the central nervous system?
The CNS consists of the brain and spinal cord. Messages are sent through the spinal cord to the brain, or the brain to the spinal cord.
54
What is the peripheral nervous system?
Neurons which connect the central nervous system to the rest of the body.
55
Your endocrine system is composed of
Endocrine glands which secrete chemicals, known as hormones, into the bloodstream.
56
Define thermoregulation.
Where the endocrine and nervous system work together to maintain body temperature. They work with the hypothalamus (in the brain); the body's "thermostat".
57
What is the thyrotropin hormone?
This hormone, released from the Hypothalamus, regulates many body activities.
58
What is the growth hormone?
Most body activities. Growth hormones can also be called the "master gland". They're released from the Piuuitary gland.
59
What is the thyroxine hormone?
A hormone from the Thyroid glan which regulates metabolism and growth.
60
What is the Cortesol hormone?
A hormone from the Adrenals gland which regulates metabolism and response to stress.
61
What is the Insulin hormone?
A hormone from the Pancreas glan which regulates blood glucose concentration.
62
Name the different types of Neurons.
Sensory neurons: carry the impulse (generated by the stimulus) TO the central nervous system.
Interneurons: carry the impulse THROUGH the central nervous system.
Motor Neurons: Take impulses to effectors such as muscles or glands.
63
Neurons are grouped together to form
Nerves.
64
Neurons, like most other eukaryotic cells, contain
A nucleus, organelles, cytosol, and a cell membrane.
65
The number of electrons in an atom = no. of
protons and neutrons meaning the atom is electrically neutral.
66
Lord Rutherford showed that there were three different types of nuclear radiation:
Alpha and Beta particles, and Gamma rays.
67
What is a dendrite?
Dendrites, which stick to the cell membrane, posed numerous receptors which receive messages from other cells.
68
One a dendrite has received a message, it moves as an electrical impulse in one direction from...
the dendrite, through the cell body, and then through a long structure called an axon.
69
Axons are covered with a white insulating substance called
Myelin, which helps speed up the conduction of the message through the neuron.
70
The gap between neurons is called a
Synapse.
71
When the electrical impulse reaches the end of an axon...
...tiny vesicles containing chemicals called neurotransmitters are transported to the cell membrane of a new neuron. These chemicals are then released into the synapse.
72
The tiny vesicles at the end of an axon contain
Neurotransmitters.
73
The neurotransmitters move across the synapse and bind to receptors on the membrane of the dendrites of the next neuron. So therefore
The next neuron converts the message to a nervous impulse and conducts it along its length.
74
Messages are carried throughout Neurons until it reaches an
Effector, such as a muscle or gland.
75
What is a reflex action?
An involuntary response where you do something without thinking about it.
76
Explain the pathway taken by messages when a reflex action takes place. What is it called?
Stimulus > Receptor > Sensory Neuron > Interneuron to spinal cord > Motor Neuron > Effector > Response.
This is called a reflex arc.
77
Breathing is a response regulated by
Chemoreceptors detecting changes in carbon dioxide levels in the blood
78
Describe a situation where a reflex action would be useful
When you accidentally touch something hot, when you receive sand in your eyes.
79
What is the difference between a reflex arc and the pathway taken by other nerve signals?
In regular reactions, the stimulus goes through the receptor, through the sensory neuron, to the interneuron, then the motor neuron, then effector to produce a response. However, reflex arcs involve the same pathway as above, except the interneuron response goes to the spinal cord, then the motor neuron.
80
Name 2 differences between your response when a reflex arc is involved and a conscious response.
Reflex arcs involve less Neurons, whereas more neurons are required for conscious responses. Reflex arcs involve the spinal cord, whereas conscious responses involve the brain.
81
Explain how the blocking of the production and action of neurotransmitters by some animals stings can cause paralysis.
Stings can empty impulses out of neurotransmitters. Interfering with the neurotransmitters' job of carrying the message to the next neuron with the transference of the message and can cause spasms and paralysis.
82
Hormones are produced in the
endocrine glands and are released directly into the bloodstream.
83
What is a target cell?
A target cell is a particular cell where hormones are carried to, as opposed to any other cell in the body.
84
Hormones control and regulate functions such as
metabolism, growth, development, and sexual reproduction.
85
The endocrine system also works with the nervous system to
regulate your body's responses to stress.
86
Unlike the speediness of the nervous system, the endocrine system
produces slow responses, and longer lasting than those of the nervous system.
87
Negative feedback helps our body to keep its internal conditions stable so that you can function effectively. An example of this is
if your body temperature is too low. The decreas in body temperature acts as the stimulus, which is detected by thermoreceptors in the body. This message is taken to the hypothalamus, which activates warming mechanisms. One of these mechanisms involves the thyroid gland. It responds by secreting thyroxine, which increases the metabolic rate the cells, releasing heat to warm you.
88
Insulin, a hormone produced by the pancreas. Acts in target cells in the
Liver.
89
The purpose of insulin is to
lower blood glucose levels if too high.
90
Glucagon is responsible for
Raising blood glucose levels if they're too low.
91
If you are excited about something, the adrenal gland releases
adrenaline into the bloodstream.
92
Adrenaline may cause...
an increase in heartbeats, the face becomes pale, and muscular actions and energy levels increase.
93
Adrenaline is often referred to as
The 'fight or flight' hormone.
94
Ethylene is a
Plant hormone that promotes a plant's ability to shed leaves.
95
RU486 is also known as the
Abortion pill.
96
RU486 not only offers possibilities of contraception, but it can
also terminate a pregnancy by blocking the action of progesterone.
97
Hormone-based contraceptions can
Come in pill forms, patches, gels, implants, and insertable vaginal rings.
98
Androgen blocks
Sperm development in males.
99
Progesterone blocks
Testosterone production in males.
100
What is a non-infectious disease?
A disease which can't be spread from one person to another — they are not contagious (transferred from one organism to another)
101
List some examples of non-infectious diseases.
Obesity, scurvy, and rickets.
102
Most non-infectious diseases are caused by
Inconsistencies and difficiencies.
103
What is an infectious disease?
Diseases caused by pathogens.
104
Name some examples of cellular pathogens.
Tapeworms, head lice, liver flukes, fungi, protozoans, and bacteria.
105
What is a non-cellular pathogen?
Pathogens which are not made out of cells.
106
What is a cellular pathogen?
Pathogens which are made out of cells.
107
Some ways in which pathogens can include
Direct contact, vectors, contaminated objects or contaminated water supplies.
108
What is direct contact?
Touching others or being touched, or through receiving airborne droplets.
109
What is a vector?
Vectors are organisms which carry the disease-causing pathogen between organisms — without being affected by the disease themselves. Mosquitos, houseflies, rats, and mice are examples of organisms which can act as vectors to spread diseases.
110
Food poisoning is often caused by
Contamination of food (or food utensils) with particular types of pathogenic bacteria.
111
Some examples of how to control the spread of diseases include examining
Personal hygiene, care with food preparation, proper disposal of sewage and garbage, chemical control of vectors, pasteurisation of milk, public education programs, quarantine laws, and the use of drugs, such as antibiotics, are some examples.
112
The organism that a parasite live in or on is referred to as its
Host.
113
The life cycle of parasites can involve
One or more hosts.
114
The primary host is the organism used for the
Adult stage.
115
The secondary host is used for the
Larval stage.
116
Parasites that live inside your body are called
endoparacites.
117
Parasites which live outside your body are called
Ectoparasites.
118
Prions are non-cellular pathogens which are
Abnormal and infectious proteins which can convert your normal protein into prion protein. When cells containing prions burst, more of these infectious proteins are released to infect other cells.
119
Prions are thought to be responsible for degenerative neurological diseases, called
Transmissible Spongiform Encephalopathies (TSE)
120
What are some examples of TSE diseases?
Kuru, Creutzfeldt-Jakob disease (CJD), and bovine spongiform encephalopathy (BSE)
121
Define what a virus is.
Viruses are another example of non-cellular pathogens. They consist of DNA or TNA enclosed within one or more protean coats. Viruses are so small that they can only be seen with very powerful electron microscopes.
122
Define what bacteria is.
Disease-causing bacteria are cellular pathogens which consist of a single cell. They can be classified on the basis of their cell shape, the organisation of colonies of bacteria and the presence or absence of structures (such as flagellum) or particular chemicals in their cell wall.
123
Define what a protozoan is.
A number of infectious diseases are caused by parasitic protozoans. These single-called organisms are usually found within the host's body.
124
Define what fungus is.
Fungi belong to one of the biggest groups of organisms. They include some that are large, such as toadstools, and others that are microscopically such as the moulds which grow on bread. Many fungi are parasites, which feed on humans, resulting in disease.
125
Explain about worms and arthropods.
Larger parasites include endoparasites such as tapeworms, roundworms, and liver flukes, and Ectoparasites such as ticks, fleas, and lice.
126
List 4 ways in which diseases can be transmitted.
Direct contact.
Vectors.
Contaminated objects.
Contaminated water.
127
Define what an antigen is.
Pathogens poses specific chemicals that are recognised as being non-self or foreign to the body. These non-self chemicals, referred to as antigens, trigger your immune system.
128
A healthy body helps you to defend yourself against infectious diseases by...
Setting up natural barriers, or lines of defence.
129
Explain about the first and second line of defence.
They're described as being non-specific. They fight the same way for all infections, regardless of whether they have encountered them before.
130
Explain about the third line of defence.
The third line of defence is specific. It fights different,y fir different types of invaders and may react differently if it has been exposed to them before.
131
Your body's first line of defence is designed to
Prevent the entry of invading pathogens. Some of these defences are physical barriers such as skin, coughing, sneezing, cilia, and nasal hairs. Others are chemical barriers, including saliva, tears, stomach acid, and acidic vaginal mucus.
132
If pathogens manage to get through your first line of defence, the second line of defence comes into play. Pathogens can enter the skin by
Cuts in the body.
133
If you have had a cut that became infected you may have noticed that the area became red, warm, and swollen (inflamed). The redness, caused by the increased blood flow to the area, and inflammation, are signs that the second line of defence has been triggered.
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134
Special types of white blood cells, phagocytes, that engulf and destroy pathogens (and other foreign material) move to the site of the infection. This action of engulfing and destroying materials is called
Phagocytis.
135
Define "lymphatic system"
The lymphatic system involves glands, which are part of a network of fine tubes running throughout the body.
136
Your lympathetic system contains
Lymph vessels, lymph nodes, lymph cells, and white blood cells. Some of these white blood cells are lymphocytes.
137
Define 'lymphocytes'.
Lymphocytes are involved in your specific immune response. When triggered by infection, your B lymphocytes divide into plasma cells. These cells produce chemicals called antibodies that are speciffic fo the invader's antigens. These antibodies assist in fhe destruction of the incading pathogen.
138
What is a B lymphocyte?
A type of lymphocyte that produces antibodies which assist in the destriction of incading pathogens; also known as plasma cells.
139
What is a T lymphocyte?
A type of lymphocyte that destroys invading pathogens by attacking them.
140
B lymphocytes divide into plasma cells which produce chemicals called?
Antibodies, which are specific to the invader's antigens. These antibodies assist in the destruction of the invading pathogen.
141
What cells do the T lymphocytes attack?
Foreign invading cells.
| Cells which have been infected.
142
For example, some T lymphocytes produce substances that can attract or activate phagocytes. Antibodies (produced by B lymphocytes) can bind to antigens, causing pathogens to clump together. This clumping makes it easier cor the phagocytes to engulf them.
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143
Your immune system can be so effective that you can be infected with a pathogen, but not devekop any symptoms. Lymphocytes can form
memory cells, so that next time you encounter the same type of invader, your immune response can be faster and stronger.
144
Defence against disease is another example of how your systems work together. Your respiratory system's lining of mucus and ciliates tubes and your digestive system's enzymes amd stomach acids help your fight against invaders. White blood cells produced in your...
bone marrow include those that will become phagocytes and lymphocytes. These defending cells will be circulated throughout your body in your circulatory system and lynphstic system fo areas of infecfion where they perform their task of destriying invaders. The remnatns of these in aders are then excreted from your body vis your excretory system.
145
Define poliomyelitis (polio).
Polio is an infectious disease caused by the picornavididae virus this disease is hifhky incectious and consequencds can inckude complete recovery, lymb and chest muscle paralysis, or death.
146
Talk about cervical cancer.
Cervical cancer is responsible cor the deaths of more than 300 Australian women each hear. A significant risk factor associated with this cancer includes the commin human papilloma virus (HPV)
147
what is the Pap test?
Women can take the pap test to see if they have abnormal cervical cells that can lead to cancer.
148
What is immunity?
Immunity is a resistance fo a particular dosease-causing pathogen. A person who is immune does not develop the disease. if the person is exposed to the antigen of a particular pathogen, or non-self material, they may make specific antibodies against it.
149
If your body makes antibodies to a specific antigen, this is described as
Active immunity.
150
If you receive antibodies from an outside source, this is called
Passive immunity.
151
Why do parents in Australia choose not to immunise their children?
Either because of safety risks, religious views, etc.
152
Explain about the natural and artificial effects of ACTIVE immunity.
Natural - Memory cells remember the antigen and you make more antibodies very quickly.
Artificial - Inject toxoids or a treated pathogen to produce antibodies.
153
Explain about the natural and artificial effects of PASSIVE immunity.
Natural - No memory cells are produced.
| Artificial - You can get antibodies from breast milk, across the placenta, of through an injection of antibodies.
154
Compare antigens and antibodies.
Antibody - Any of various proteins which are produced as a result of the presence of a foreign substance in the body and which act to neutralise or remove that substance.
Antigen - A substance that stimulates the production of antibiotics.
