HSC Biology Marathon 2015 (2 Viewers)

[Khan.Paki]

Here's another question if anyone wants to have a go.

Define 'mutagen' and discuss the evidence for the mutagen nature of radiation (3 marks).

A mutagen is an environmental factor that increases the rate of mutation - a change in DNA base sequence. Marie Curie forms a basis of evidence. Carrying uranium in her pockets, she was unaware of its disastrous effects and consequently died of leukemia. Furthermore people who reside in areas with high levels of radiation such as Chernobyl and Hiroshima show high incidents of cancer.

 

[Mr_Kap]

Describe the energy transformations of sound through the ear. 4 MARKS

 

[Flop21]

What do we need to know about malaria? Do we need to know the life cycle of the protozoa in detail?

And what about the history of the discovery of its cause? Is knowing about Ronald Ross enough?

 

[Mr_Kap]

What do we need to know about malaria? Do we need to know the life cycle of the protozoa in detail?

And what about the history of the discovery of its cause? Is knowing about Ronald Ross enough?

Well im doing malaria as my infectious disease that I have to know so i know it in a bit of depth, so depending on the marks i can write enough. The history i would know maybe 3 people just in case...you never know. I can't remember the other two apart from Ronald Ross off the top of my head right now though.

 

[Flop21]

Well im doing malaria as my infectious disease that I have to know so i know it in a bit of depth, so depending on the marks i can write enough. The history i would know maybe 3 people just in case...you never know. I can't remember the other two apart from Ronald Ross off the top of my head right now though.

Same here, but how much depth. Obviously what the dot point says, but for 'transmission' are you going to know the whole life cycle of the thing? Like sporozoites in blood circulation, then form merozoites etc. etc.

Edit: also for the scientists I'll probably remember Charles Laveran > Giovanni Grassi > Ronald Ross

 

[Mr_Kap]

Same here, but how much depth. Obviously what the dot point says, but for 'transmission' are you going to know the whole life cycle of the thing? Like sporozoites in blood circulation, then form merozoites etc. etc.

I learnt all of that from Ahmad Shah revised edited perfected notes, yeh.

For transmission
 The Anopheles mosquitoes are the hosts that transmit the disease to humans during the blood-sucking process. When an Anopheles mosquito bites an infected person, a small amount of blood infected with microscopic malaria parasites is taken as it sucks the gametocytes (the sexual forms of the parasite), along with blood. The parasite grows and matures in the mosquito's gut for a week or more. The gametocytes continue the sexual phase of the cycle, which produced and the immature form of plasmodium known as sporozoites. These then travels to the mosquito's salivary glands. When the mosquito next takes a blood meal, these parasites mix with the saliva, are injected with the bite, when this female mosquito bites the man for a blood meal, which it needs to nourish its eggs, it inoculates the parasites into human blood stream, thus spreading the infection and malaria transmission is complete.
 Once in the blood, the parasites travel to the liver and enter liver cells, to grow and multiply. After as few as seven days or as long as several years, the parasites leave the liver cells and enter red blood cells, which normally carry oxygen in the blood to tissues that need it.
 Once in the red blood cells, the malaria parasites continue to grow and multiply. After they mature, the infected red blood cells rupture, freeing the parasites to attack and enter other red blood cells. Toxins released when the red cells burst are what cause the typical symptoms of malaria

The red i would only mention if it was like a 6 marker or something

obviously i would cut down my response in the exam as well.

 

[Mr_Kap]

– 1880: Charles Laveran observed micro-organisms in fresh blood from malarial patients and that malaria was caused by the plasmodium micro-organisms.
– 1894: Patrick Manson proposed that malaria is transmitted by mosquitoes.
– 1897: Ronald Ross established that the protozoan Plasmodium was the cause of malaria, he showed it can be trasmitted and thus established the cycle of transmission through experiments with mosquitos and birds.

 

[Khan.Paki]

I don't think Laveran showed it was plasmodium microorganism. He simply observed micororganisms in the blood of malarial patients. It was actually Ross who discovered it the Plasmodium protozoan.

 

[Mr_Kap]

You performed a first-hand investigation to estimate the size of blood cells.
(a) How did you estimate the size of the cells?

 

[Loudvicuna]

You performed a first-hand investigation to estimate the size of blood cells.
(a) How did you estimate the size of the cells?

1. Place a mm grid on microscope stand
2. Place blood slide on top
3. count the amount of blood cells that fit in a line and divide by the number of cells to find single cell size
4. Divide by 1000 to get individual cell size into micrometer

Red blood cell:6-8 um
White blood cell: 12-15um

 

[BlueGas]

Explain how an understanding of the source of variation in organisms has provided support for Darwin’s theory of evolution by natural selection. (3 marks)

 

[Mr_Kap]

Explain how an understanding of the source of variation in organisms has provided support for Darwin’s theory of evolution by natural selection. (3 marks)

When Darwin came up with this theory of evolution, it was lacking significant evidence of HOW organisms can mutate, hence was not a complete theory. There are many sources of variation which could occur in organisms. These include a mutation in DNA, and the processes of crossing over, random segregation and indpendant assortment during meiosis. By udnerstanding mechanisms of variation such as these, we can see how natural seection has become possible, as Darwin was not sure how the organisms came to be variated from eachother, meaning his theory was weaker. Hence an understanding of the sources of variation in organisms has sterngthened the evidence for Darwins theory of evolutin via natural selection

 

[Flop21]

Variation in organisms is a large component in Darwin's theory of evolution by natural selection. Variation allows organisms to have favourable traits that allow them to survive (survival of the fittest), especially in a changing environment. Understanding the source of variation in organisms allows us to understand how this variation comes about. The crossing over of genetic material in meiosis and random segregation of chromosomes create variation in the genotype of an organism. Mutation additionally provides variation, and is how organisms receive the traits to possibly allow them to better survive under their environmental selective pressures.

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lol that was bad sorry.



Evaluate the effectiveness of vaccination programs during the last century using an example in your answer. (4 marks)

 

[Mr_Kap]

Variation in organisms is a large component in Darwin's theory of evolution by natural selection. Variation allows organisms to have favourable traits that allow them to survive (survival of the fittest), especially in a changing environment. Understanding the source of variation in organisms allows us to understand how this variation comes about. The crossing over of genetic material in meiosis and random segregation of chromosomes create variation in the genotype of an organism. Mutation additionally provides variation, and is how organisms receive the traits to possibly allow them to better survive under their environmental selective pressures.

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lol that was bad sorry.

[/B]

If i combine a few bits of my answer with yours then it would have been better. Mine was worse than yours but i talked more about providing support for Darwin's theory

 

[Mr_Kap]

Evaluate the effectiveness of vaccination programs during the last century using an example in your answer. (4 marks)

Over the last century, vaccination programs have no doubt had enormous impact on our society for the better. Vaccination programs involve mass vaccinations of the people in order to PREVENT them from contracting the disease, rather than waiting for people to contract the disease and attempt to make a cure. Sometimes, vaccination can even lead to the eradication of specific diseases. This can be seen with smallpox vaccination programs. Smallpox is a disease that has been around since around 10000BC and in the 19th century was responsible for 1/10 deaths in Europe, and was spreading around the world rapidly. In 1967 WHO performed smallpox vacinnations on a global scale, and by 1980 smallpox had been sucesfully eradicated. Hence it can be seen especially through this example, that vaccination programs have the potential to be very effective in preventing diseases, sometimes even eradicating the disease all together.

 

[Mr_Kap]

Someone help me!
Can someone give me their prac notes on:

• Preform a first-hand investigation or process information from secondary sources to develop a simple model for polypeptide synthesis.

Please anyone ?

 

[Flop21]

Someone help me!
Can someone give me their prac notes on:

• Preform a first-hand investigation or process information from secondary sources to develop a simple model for polypeptide synthesis.

Please anyone ?

You just have to make up a 'model' using real life objects. E.g. use coloured pegs to represent the nucleotides, peg complementary ones together. Thread a piece of string through the pegs to represent mRNA etc.

Could even just have jelly beans and marshmallows etc.

 

[Flop21]

Compare homoeostasis and enantiostasis.

 

[tfw english]

Compare homoeostasis and enantiostasis.

Homeostasis is the maintenance of a constant internal environment, however, enantiostasis is where an organism can maintain maintain its normal functioning despite the outside environment changing. It can do this whilst not maintaining homeostasis - e.g. the salt levels in an organism can increase as the tide comes into an estuary but it has mechanism so that its normal metabolic and physiological functioning can be maintained at a normal level.

Homeostasis is that it's detected as an internal change that is corrected through negative feedback whereas enantiostasis is to the external environment and doesn't counteract it in the same way as homeostasis.

 

[Khan.Paki]

Over the last century, vaccination programs have no doubt had enormous impact on our society for the better. Vaccination programs involve mass vaccinations of the people in order to PREVENT them from contracting the disease, rather than waiting for people to contract the disease and attempt to make a cure. Sometimes, vaccination can even lead to the eradication of specific diseases. This can be seen with smallpox vaccination programs. Smallpox is a disease that has been around since around 10000BC and in the 19th century was responsible for 1/10 deaths in Europe, and was spreading around the world rapidly. In 1967 WHO performed smallpox vacinnations on a global scale, and by 1980 smallpox had been sucesfully eradicated. Hence it can be seen especially through this example, that vaccination programs have the potential to be very effective in preventing diseases, sometimes even eradicating the disease all together.

I think you should have mentioned Edward Jenner he developed the vaccine.