School Certificate Science MARATHON (1 Viewer)

[zavier]

what are trans-genic species?? list advantages and disadvantages.

A trans-genic species is species which has had its genome "changed" so that is has a new property that is deemed beneficial to the species, consumers etc., for whatever reason, and it will be passed down to its offspring so that the genetic change is bred into the species. Basically it is any genetically modified organism.

There is similar controversy to this as with all the other biotechnology questions on this thread. Things like should we play "god", creating new allergens etc.

Advantages are being able to breed in beneficial factors to the species being modified, can be used for medical advances, can give pest resistance to pets etc.

Disadvantages are that other organisms can gain resistance, i.e a pest gaining resistance to a pest resistant plant etc.

My Question: Explain the Greenhouse effect.

 

[lpodnano]

A trans-genic species is species which has had its genome "changed" so that is has a new property that is deemed beneficial to the species, consumers etc., for whatever reason, and it will be passed down to its offspring so that the genetic change is bred into the species. Basically it is any genetically modified organism.

There is similar controversy to this as with all the other biotechnology questions on this thread. Things like should we play "god", creating new allergens etc.

Advantages are being able to breed in beneficial factors to the species being modified, can be used for medical advances, can give pest resistance to pets etc.

Disadvantages are that other organisms can gain resistance, i.e a pest gaining resistance to a pest resistant plant etc.

My Question: Explain the Greenhouse effect.

The greenhouse effect is the rise in temperature that the earth experiences because of certain gases in the atmosphere (e.g carbon dioxide etc.) trap energy from the sun. Without these gases heat would escape back into the atmosphere and the earth's average temperature would be about 16 degrees celcius colder. Because of how they warm the world, these are known as greenhouse gases.

 

[Riot09]

q.outline newtons second law using an example?

 

[freedragon]

Newtons second law:

When force is applied, an object will accelerate and the acceleration will depend on the mass of the object

F=ma

force=mass x acceleration

for example, the acceleration of a car with the same force applied will be greater than that of a truck. This is because the car has a smaller mass and therefore a greater acceleration (when the force applied does not change)

 

[freedragon]

question. explain the uses of different types of different electromagnetic waves

 

[zxreth]

radio waves - communication, transmit radio and tv signals and radar in air traffic control.
microwaves - communication, heating food, used in radar speed guns by police.
infra-red - heat given off by objects, used to find bodies under collapsed buildings.
visible light - sight, photography and photosynthesis.
Ultra violet rays - used in fluorescent lamps and for sterilisation.
X-rays - used to treat cancer, other various medical uses and to find faults in metals.
Gamma - used to sterilise medical equipment and find the thickness of metals.

 

[salih08]

Evaluate an impact of an environmental problem. In your answer, show how science can help reduce the impact on society and the environment. (6 marks, SC 2007 Question 64)

 

[zxreth]

why does a bulb not work if the filament is broken?

 

[salih08]

why does a bulb not work if the filament is broken?

not sure but i think it breaks thy continuous cycle of heating and releasing light.
is this in our syllabus?

 

[zxreth]

i'm not too sure, but i remember seeing it in one of the past sc papers.

 

[CorForce]

Describe some everyday uses and effects of electromagnetic radiation, including applications in communications technology?

 

[salih08]

Describe some everyday uses and effects of electromagnetic radiation, including applications in communications technology?

look above

radio waves - communication, transmit radio and tv signals and radar in air traffic control.
microwaves - communication (satellite), heating food, used in radar speed guns by police.
infra-red - heat given off by objects, used to find bodies under collapsed buildings.
visible light - sight, photography and photosynthesis.
Ultra violet rays - used in fluorescent lamps and for sterilisation.
X-rays - used to treat cancer, other various medical uses and to find faults in metals.
Gamma - used to sterilise medical equipment and find the thickness of metals.

 

[salih08]

Name two properties of plastic that make it useful.

they are water resistant and fire resistant and flexible (?)

PLZ someone answer this: 3 observations is a metal+acid reaction (eg. magnesium+HCL).

hint: bubbling is one. now name the other 2.

 

[purpledino64]

Arghhhhhhhh u guys are overreacting so much we wont need to know all this stuff in so much detail. like seriously wing it and u'll get a band six

 

[CorForce]

Relate pollution to contamination by unwanted substances

 

[Nerdygirl]

they are water resistant and fire resistant and flexible (?)

PLZ someone answer this: 3 observations is a metal+acid reaction (eg. magnesium+HCL).

hint: bubbling is one. now name the other 2.

1 bubling giving of hydrogen gass
2 Heat given off
3 colour change due to salt forming (magnesium developes a coating of the salt)

Question: Descibe the processes of mieosis and mitosis including the differences between them.

 

[Uzername]

Mitosis - identical cells are reproduced, there are 2 cells produced. They are both exactly the same as the parent cell.
- Diploid - all 46 chromosomes are present
- Mitosis is used for the growth, repair, and maintenance of human body cells.

Meiosis - 4 cells produced, all are identical.
- Haploid - 23 chromosomes present, half the amount of a normal cell.
- Used for sexual reproduction, and created in ova/testes.

 

[salih08]

Mitosis - identical cells are reproduced, there are 2 cells produced. They are both exactly the same as the parent cell.
- Diploid - all 46 chromosomes are present
- Mitosis is used for the growth, repair, and maintenance of human body cells.

Meiosis - 4 cells produced, all are identical.
- Haploid - 23 chromosomes present, half the amount of a normal cell.
- Used for sexual reproduction, and created in ova/testes.

good answer except ova is plural for ovum which is the egg. it is created in the ovary

 

[Mudkip94]

My Question: Explain an orbit, why dosen't a satellite just fall to the ground 'n' stuff?

 

[Xc3llerator]

My Question: Explain an orbit, why dosen't a satellite just fall to the ground 'n' stuff?

Because the satellite is always falling and because earth is round it keeps going in a circle. The satellite has to go fast enough to achieve this, if not it would fall back down to earth