Biology Marathon 2006 (1 Viewer)

[angmor]

theres not been a biology marathon on this forum at all? wtf man.
ok here goes
1. i post question
2. you answer. in your answer also include a question for the next person.
3. next person answers.
4. etc etc
please remember to ask questions from the core topics only.

My question: Explain why the removal of carbon dioxide from cells is necessary for living cells.

 

[mica]

Here it goes..

Spoiler

Cells need to remove the carbon dioxide becuase it can dissolve in water and form harmful carbonic acid. The carbonic acid lowers the PH of the cellular fluid which in turn has a negative effect on enzyme activity (increases or decreases depending on level of CO2 away from normal level).
Since enzymes are required for all chemical reactions within cells, it is important to maintain normal functioning to maintain normal functioning of the body.

Next Question:
Explain the role of the kidney in Fish and Mammals

Thanks
Michael

 

[fishy89sg]

alrighty

Spoiler

it digests food and kills bacteria

Next:

name four living things that contain chlorophyll

 

[Tim035]

alrighty

Spoiler

it digests food and kills bacteria

Next:

name four living things that contain chlorophyll

Thats not even close to right:

Spoiler

The kidney plays a role in homeostatis, forming and excreting urine while regulating water and salt concentration in the blood. It maintains the precise balance between waste disposal and the animals needs for water and salt in salt water the kidney excretes small quantities of isotonic urine. In freshwater the kidney work continously excreting copious quantities of dilute urne

 

[fishy89sg]

ah man i need to revise my preliminary bio notes

im a bit stuck with this quesion while i revised my notes

Q. what is the difference between external and internal fertilisation

 

[Mohit7]

A: Internal fertilisation has to happen directly which means the male and female have to sexual contact while in External fertilisation the male releases his gamates into an aquatic environment and they hopefully reach the female.


Q:How come fish don't sink when they go to sleep like sharks?

 

[UzurOger]

A:

Spoiler

First of all Shark are constantly moving, this is because they need to move to allow water to flow through their gills which allow them to breathe. So if they stopped moving they would not only sink but also DIE.

Also sleep is a very general term since most fish don't even have eyelids. So I'm assuming your talking about really small fish in comparison to sharks. Well small fish use small rocks and and sand to control bouncy and since when they are "Sleeping" the amount of sand\rock doesn't change they don't sink.

I'm not entirely sure what the correct answer is but i hope i was close

Q: Define the Term Adaptive Radiation (Divergent evolution)

 

[Tim035]

A:

Spoiler

First of all Shark are constantly moving, this is because they need to move to allow water to flow through their gills which allow them to breathe. So if they stopped moving they would not only sink but also DIE.

Also sleep is a very general term since most fish don't even have eyelids. So I'm assuming your talking about really small fish in comparison to sharks. Well small fish use small rocks and and sand to control bouncy and since when they are "Sleeping" the amount of sand\rock doesn't change they don't sink.

I'm not entirely sure what the correct answer is but i hope i was close

Q: Define the Term Adaptive Radiation (Divergent evolution)

Ans: If a proportion of a species becomes separated and isolated by some external means they will most likely face different enviromental pressures. This will result in the selection of different characteristics in the species in order to most efficently exploit this enviroment, eventually the two groups will become so different they will not be able to interbreed to produce fertile offspring thus becomming a new species. This was seen in Darwin's observations of the different selected characteristics in finches living on the galapogas islands.

My questions: Describe how the origins of genetic variability support Darwin's theory of evolution

 

[aileenli]

^ genetic variation means that there is continual change in the gene pool of a population (so a cloned population would have no genetic variation). Darwin's theory of evolution states that those equipped with the characteristics that help them survive environmental pressures (such as food, mates, space, water) with the lest exertion of energy. so in a gene pool, there are some organisms whose characteristics will help them survive better than others (eg. moths that are darker will survive better on dark coloured tree than white moths) and they will pass these characteristics down to their offspring.

My question: why are there so many prelim students who ask stupid questions on this thread?

Alright, seriously my question II: Name four blood products and their uses. why is further research into artificial blood necessary?

 

[punk_tartan]

^

Alright, seriously my question II: Name four blood products and their uses. why is further research into artificial blood necessary?

blood products

factor 8- treatement for haemophilia
platelets to control hemorighhing , often in leukemia and other cancer patients
white cells - for people with low cell count, not producing their own or with serious bacterial infection
red cells- treatment of anemia or traumatic bleeding


reasons why reasearch into artifical blood is nesscesary- theres an estiates hortage of 100 million units worldwidem and the artifical blood removes the possiblity of blood bourne diseases as it can be chemically pastuerised. It also does not require cross matching and be be stored for longer than donated products

 

[aileenli]

hey! you forgot to post a question! anyway, i will post another one....

question: outline a model for natural selection

 

[Tim035]

By model do you mean as in the practical performed such as the different coloured tooth picks? or an example such as the growing number of bacteria resistant to anti biotics sa. Staphlococus Aureus?

 

[aileenli]

why don't you do them both?

 

[housemouse]

alrighty

Spoiler

it digests food and kills bacteria

lolllllllllllllllllll

 

[Petinga]

Natural selection can be modelled using coloured toothpicks(red and green). This involves 200 red and 200 green toothpicks being scattered by a few students over a defined greengrassland and a defined area of asphalt (control). A few student are then sent to collect as many toothpicks as possible in a time frame of 2 minutes. The results are then tabulated and compared.
This shows that green toothpicks are favoured by the environent and hence overtime will become the prevalent phenotype with red becomioing exintct.

An example of natural selection is the deveolpment of mosquito reisistance ot the insectide DDT. The firsty subsequnet sprayings killed a large majority of the population however very few naturally immune survived, reproduced and passed on their desired traits to the next generatiuon of offspringf. Thus overtime the number of naturally immune in the population increases hence shows natural selection cleary.

Question: Define Enantiostasis and the importance to estaurine organisms.

 

[meg_1_2_3_4_5]

Enantiostasis is the maintenance of normal metabolic and physiological functioning, in the absence of homeostasis, in an organism experiencing variations in its environment.

All organisms living in an estuary experience large changes in salt concentration in their environment over a relatively short time span, with the tidal movement and mixing of fresh and salt water (euryhaline, eg- mangroves)

One strategy to withstand such changes in salt concentrations is to allow the body's osmotic pressure to vary with that of the environment. Organisms that do this are called osmoconformers.
As the salt concentration of body fluids in an osmoconformer changes, various body functions are affected, such as the activity of enzymes. For normal functioning to be maintained another body function must be changed in a way that compensates for the change in enzyme activity.


My question:
Explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms

 

[Petinga]

The processes of diffusiion and osmosis are inadequate in removing dissolved nitrogenous wastes becuase they are both examples of passive transport which rely on the random movement of molecules. Diffusion is too slow for the normal functioning of the body and is non selective of useful solutes. osmosis only deals with the movment of water and thus water would be removed and nitrogenous wastses kept in the body of the organism.

This is resolved by having a kidney which dumps everything outside of the body and selectively reaborbs the useful solutes.


Question: Describe the experiments carried out by Gregor Mendel and list 3 aspects that lead to his success

 

[wrxsti]

Gegor Mendel showed his thoughts on DNA, he was successful cause he was a scientist

 

[Dr_Doom]

Question: Describe the experiments carried out by Gregor Mendel and list 3 aspects that lead to his success

Answer:

Spoiler

Gregor Mendel studied the different traits produced by pea plants such as pod shape/size, flower colour, seed shape/size, stem height. He crossed two pure bred species (eg one tall and one short) pea plant, then recorded that all offspring were tall. When he crossed the offspring (generation 1) he found that their offspring (generation 2) were tall and short in the ratio 3:1.

- He used species with easily identifiable characteristics
- Crossed large number of plants at a time
- Experimented with a range of traits / characteristics

Question: How do suppressor proteins affect gene expression? Give an example.

 

[Tim035]

Gene expression in when a gene is "switched on" resulting in the production of a functional protein. Gene expression is linked to the transfer of information via mRNA and tRNA to produce polypeptides. Proteins are needed for the structure of cells as well as growth, repair and enzyme production which controls all metabolic reactions. Malfunctions in gene expression cause or predispose humans to a number of diseases because they cause cells to produce inappropriate types or amounts or proteins. Such an example is cystic fibrosis, one of the most common single gene disoders.
Gene expression is also important in the regulation and control of cell division. Proto-oncogenes produce proteins that stimulate cell growth and division. Tumour supressor genes produce proteins that slow down or stop cell growth and division. Mutated oncognes cause uncontrolled cell replication, mutations in tumor supressor genes result in the loss of the ability to successfully control cell division. This uncontrolled cell division results in growths such as cancer.

Hmm my question: Account for how the various structures which make up the xylem and phloem assist in the transportation of different materials through plants.