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March 28, 2024, 10:05:02 pm

Author Topic: Challenging biology questions  (Read 5957 times)  Share 

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Bri MT

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Re: Challenging biology questions
« Reply #15 on: January 27, 2020, 01:30:12 pm »
+4
Multiple Choice
Question 1
B: (as the ending indicates it is an enzyme which would work to speed up a reaction

Question 2
Honestly not sure with this one. I think that it couldn't be A because although the enzyme speeds up the reaction, cooking it would not increase the amount of the enzyme present. Could possibly be B, as temperature could act as a catalyst. It doesn't seem to be C because catalase would work best at its optimum pH of 7 and that it doesn't seem to be D because whether or not the potato was cooked was not part of the list of factors that the student kept the same/changed in the second experiment. Scratch that, it's C as that would affect the pH but would provide more substance to be converted into oxygen. That took me longer than it should have.

Question 3
D. It would be present in water as cellular respiration would have taken place meaning that the oxygen would be converted into CO2 and H2O, however the CO2 would be expelled as the animal breathed out.

Question 4
D. Self explanatory.

Question 5
B. Humans do not become less susceptible to antibiotics, nor do viruses. Antibiotics act on bacteria and due to their overuse, resistant bacteria have been allowed to survive and reproduce and cannot be effectively treated.

Short Answer
Question 1
a)I would draw my arrow straight down the page, directly through the membrane.
b) As there is a higher concentration of molecules outside of the cell diffusion would lead them to diffuse into the cell along their concentration gradient until equilibrium is established. The molecules are small and hydrophobic, meaning that they are attracted to fats and so could cross quite easily across the membrane directly through the fatty acid tails of the phospholipids without needing to travel through a protein channel.




feedback
There are a couple of questions where you have the right answer but your reasoning is flawed. I also encourage you to revisit question 4

Erutepa

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Re: Challenging biology questions
« Reply #16 on: January 28, 2020, 09:30:11 am »
+4
Awesome work on attempting these challanging Bio questions Chocolatemilkshake and Laura!
The science games are only (just over) one week in, so there is still plenty of time to earn points by completing the challanaging questions for these week and last week!
Here is your new batch of questions - make sure you blow on them as they are fresh out of the oven
Multiple Choice
Question 1
In India, a group of scientists was studying fossils from a coal deposit formed during the Permian period (290–245 million years ago). They found three fossil species from the same genus in different levels (strata) of the coal. When radiocarbon dating on these fossils was performed, it showed exactly the same levels of carbon-14 in all three fossil species. The data is summarised in the table below.

Which one of the following is the correct conclusion to draw from these findings?
A) There is no evolutionary relationship between these three fossil species.
B) G. clarkeana is the common evolutionary ancestor of G. major and G. obliqua.
C) As carbon dating is a more reliable dating technique than analysis of strata in coal deposits, the fossils of G. major, G. obliqua and G. clarkeana are all of the same age.
D) An analysis of strata in coal deposits is a more reliable dating technique than carbon dating for Permian fossils; the fossil of G. major is younger than the fossil of G. obliqua.
Question 2
The following images show stages in meiosis in the order in which they occur.

Which one of the following statements is correct?
A) During the stage shown in image 9, chromatids separate.
B) Cells after the stage shown in image 10 are haploid.
C) During the stage shown in image 11, DNA will be replicated.
D) Homologous chromosomes pair up in the stage shown in image 12.
Question 3
In garden pea plants, Pisum sativum, the shape of the pods can be infl ated or constricted, while the colour of the pods can be yellow or green.

Experiment 1: Pea plants homozygous for infl ated pods were crossed with pea plants homozygous for constricted pods. The offspring were then crossed among themselves. Experiment 2: Pea plants homozygous for yellow pods were crossed with pea plants homozygous for green pods. The offspring were then crossed among themselves. The resulting phenotypic data for the F2 generations from each experiment are shown below.

Inflated pod plants from the F1 generation were crossed with their constricted pod parents to produce a total of 280 offspring. The expected numbers of offspring with each phenotype are
A) 280 inflated : 0 constricted
B) 210 inflated : 70 constricted
C) 70 inflated : 210 constricted
D) 140 inflated : 140 constricted
Question 4
Fossil remains of a number of individuals from the genus Australopithecus were found at various sites in the eastern half of Africa and have been dated to between 3–4 million years old.
These fossil remains
A) are descendants of Homo erectus.
B) represent the oldest evidence found of primates.
C) show early evidence that hominins were bipedal.
D) represent the earliest examples of the hominoid super-family.
Question 5
In some plants, a modified leaf forms an insect trap. ‘Motor cells’ are located along the midrib of the modified leaf. In their resting state, these cells are turgid and contain potassium ions at a concentration higher than the surrounding fluid. When the trap is triggered, potassium ions stream out of the motor cells through ion channels. The cells lose their turgidity. The pressure in the surrounding cells then causes the modified leaf to bend and so the trap closes.
Taking into consideration the opening and closing of the trap, which one of the following statements is true?
A) When the trap is opening, potassium ions accumulate in the motor cells by diffusion.
B) When the trap is opening, water accumulates in the motor cells by active transport.
C) When the trap is closing, potassium ions leave the motor cells because of the pressure in the surrounding cells.
D) When the trap is closing, water leaves the motor cells by osmosis.
Short Answer
Question 1
Many people in Australia have high blood cholesterol levels. High blood cholesterol levels are linked to coronary heart disease. Cholesterol is produced by a series of chemical reactions.
One of the reactions in the series is shown below

Lovastatin is used to treat high blood cholesterol. When administered, the lovastatin is converted to an active form that is a reversible competitive inhibitor of HMG-CoA reductase
a) What does this suggest about the structure of the active form of lovastatin? (1 mark)
b) To successfully treat high levels of cholesterol, lovastatin must be taken every day at regular time intervals.
Considering the mode of action of lovastatin, why is it important to prevent the blood concentration of lovastatin from becoming too low? (2marks)
Question 2
Australian marsupials, such as wallabies, kangaroos, wombats and koalas, give birth to very undeveloped young called joeys. When a joey enters the mother’s pouch, it is at a stage equivalent to a seven-week-old human fetus. It spends many weeks in the pouch feeding on milk produced by mammary glands. Although the pouch provides protection from predators, it is neither sealed nor sterile.
a) What is meant by the term ‘sterile’ in the context given? (1 mark)

The joey’s primary immune tissue (in the bone marrow and thymus) does not mature until 30 days after birth and its humoral immunity does not function effectively until 90 days after birth. Biologists have analysed milk samples from several marsupial species and found that they contain various antibodies. Some of the antibodies in the mother’s milk remain in the joey’s gut, while others cross the gut wall and enter the joey’s bloodstream.
b) Describe at a molecular level how antibodies perform their function (2marks)
Question 3
DNA hybridisation is a molecular technique used to determine the evolutionary relationships between species. DNA is extracted from each species and cut into fragments.
How does the technique of DNA hybridisation enable scientists to determine the evolutionary relationships between species? (2marks)
Question 4
In 2013, about 1500 fossil bones of a hominin species were found in a cave in South Africa. From these bones, scientists have managed to construct an almost complete skeleton. The fossil bones have some features in common with those of the genus Australopithecus; however, they have enough similarities to the genus Homo that scientists have classified the fossil skeleton as belonging to a new species, Homo naledi.
What are two features that the fossil skeleton would need to have in order to be classified in the genus Homo and not in the genus Australopithecus? (2marks)
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caffinatedloz

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Re: Challenging biology questions
« Reply #17 on: January 28, 2020, 11:46:38 am »
+3
Multiple Choice
Question 2
B. In the ninth image, the first round of division, homologous chromosomes are pulled away from their pairs. That means that the two cells forming in the tenth image each have one full set of chromosomes (23) that are each double stranged, making them haploid. This also means that A is wrong, as the chromatids will not separate until two cells become four. It also means that D is wrong because there are no homologous pairs of chromosomes in the twelfth image as the homologs have already been separated. C is wrong as DNA is replicated during the S phase of interphase, not during mitosis or meiosis.

Question 3
A. The data from the F2 generation suggests that inflated pods are dominant. That means that when homozygous II is crossed with ii (parental generation), all offspring will have the Ii genotype, meaning that they have inflated pods phenotypically. This makes sense as when Ii and Ii are crossed, approximately 75% would have inflated pods, and 25% would have constricted, which is what is evident in the F2 generation.


Erutepa

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Re: Challenging biology questions
« Reply #18 on: January 30, 2020, 10:42:12 pm »
+4
Question 3
A. The data from the F2 generation suggests that inflated pods are dominant. That means that when homozygous II is crossed with ii (parental generation), all offspring will have the Ii genotype, meaning that they have inflated pods phenotypically. This makes sense as when Ii and Ii are crossed, approximately 75% would have inflated pods, and 25% would have constricted, which is what is evident in the F2 generation.
You got question 2 spot on, however question 3 isn't quite there.
To put you on the right track without giving the answer away,
Spoiler
from the question stem, we know that the parental population (homozygous for constricted and homozygous for inflated) were crossed to produce the F1 generation. The F1 generation were then crossed amoungst themselves to give the F2 generation.
From the data given by the F2 generation (the far higher frequency of the inflated phenotype), we can assume that the inflated allele/gene varient is dominant and the constricted allele is reccesive.
By drawing out a punnet square for the crossing of the parental population, we can identify that all members of F1 are heterozygous (they will contain both the allele for constricted pods and inflated pods, however will present the inflated phenotype due to its dominance). The constricted pod parents we know to be homozygous for constricted pods, so cross that the question is asking about is between  heterozygous offspring and the homozygous for constricted pods parents.

Hopefully this helps in getting to the answer!
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Erutepa

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Re: Challenging biology questions
« Reply #19 on: February 03, 2020, 09:20:24 pm »
+1
As we are entering the second half of the epically epic science games, its as good a time as ever to jump into this thread and answering some tough questions.
Since last weeks questions didn't see to much activity, there won't be a fresh batch of questions this week as I don't want to bombard users with too many questions. So for now, the last couple weeks of questions will sit here patiently waiting to be answered.
If you haven't had a go yet at any questions or have only answered some of the questions, now would be a great time to have a crack at them and earn some points. And remember, don't worry about being wrong - if you make an error or get the wrong answer, we can give you some feedback and hopefully guide you to the correct answer!

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