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August 02, 2021, 01:25:16 pm

Author Topic: Biology Misunderstandings  (Read 2684 times)  Share 

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Sine

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Biology Misunderstandings
« on: January 13, 2020, 11:15:26 pm »
+7
Biology Misunderstandings

The aim of this thread is to dispel any misunderstandings or mistruths within the subject of Biology. Hopefully, this will give everyone a better understanding of the subject, allow everyone to revise biological concepts and stop students from falling into some of the common traps of understanding.

E.g. A pair of posts in this thread would be in the following form
Post 1: -misunderstanding- (in italics or clearly labelled to reduce confusion)
Post 2: -explain what the truth actually is (at a year 11-12 level)

For example:
User 1: Antibiotics can be used effectively to treat bacterial and viral infections
User 2: Antibiotics are medicines that treat bacterial infections. Antibiotics canít kill or clear viruses because viruses donít have the physical or chemical structures that antibiotics target in bacteria.

Everyone is encouraged to participate in this thread whether you have just started studying biology this year or have a degree in it   

Iíll begin easy
Misconception: All cells have a cell wall.

Pearlmilktea

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Re: Biology Misunderstandings
« Reply #1 on: January 13, 2020, 11:29:23 pm »
+7
Omg I love this!

Biology Misunderstandings

Iíll begin easy
Misconception: All cells have a cell wall.

No, not all cells have a cell wall. In fact, most don't.

An example of a cell with a cell wall would be a plant cell. It provides stability and is made out of cellulose.
However, animal cells on the other hand only have a cell membrane. This protects the cell and is controlled to ensure only the correct substances enter and exit.

Ok misconception
Metabolism refers to how fast your body digests food:o

Such a common misconception
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Sine

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Re: Biology Misunderstandings
« Reply #2 on: January 13, 2020, 11:39:10 pm »
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Ok misconception
Metabolism refers to how fast your body digests food:o

Such a common misconception

Metabolism is the entire complement of biochemical reactions that occur within a living organism. This involves anabolism (the build up of products) and catabolism (the breaking down of substances).

Digestion on the other hand refers to the process organisms undertake to extract nutrients from the food the organism eats whilst any waste material is left to be eliminated from the organism. Digestion involves the mechanical breakdown of food such as from chewing and the chemical digestion from the action of stomach acid which breaks down certain proteins.

laura_

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Re: Biology Misunderstandings
« Reply #3 on: January 14, 2020, 06:40:32 am »
+4
//
Forgot a new misconception, Sine. ;D I'll add one on.

Misconception: Cytoplasm and cytosol are the same thing.
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Chocolatemilkshake

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Re: Biology Misunderstandings
« Reply #4 on: January 14, 2020, 07:38:08 am »
+5
Misconception: Cytoplasm and cytosol are the same thing.
Cytosol is just the fluid surrounding the organelles within the cell (does NOT include fluid within the organelles). On the other hand, cytoplasm includes both the fluid surrounding the organelles as well as the fluid within the organelles (excluding the fluid within the nucleus).

Misconception: Coenzymes (and cofactors) are made of protein or are a type of enzyme.
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Re: Biology Misunderstandings
« Reply #5 on: January 14, 2020, 10:41:47 am »
+6
Cytosol is just the fluid surrounding the organelles within the cell (does NOT include fluid within the organelles). On the other hand, cytoplasm includes both the fluid surrounding the organelles as well as the fluid within the organelles (excluding the fluid within the nucleus).

Misconception: Coenzymes (and cofactors) are made of protein or are a type of enzyme.
Cofactors are a broad catagory of small non-protein organic molecules (known as coenzymes) aswell as metal ions which bind to and interact with the active sites of enzymes to facilitate the catalytic action of the enzyme. They are by definition non-protein molecules and are not classified as an enzyme for that reason (as well as for the fact that they themselves don't really catalyse the reaction, they meerly play a role in supporting/enabling an actual enzyme to do so).
While not particulalrly relevant at a VCE level a very similar misconception related to this is that Coenzymes and cofactors are the same thingwhich is not the case and was breifly covered here  :)

MisconceptionSelection pressures acting on a population cause mutations to occur and thus change the allele frequency of that population
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Re: Biology Misunderstandings
« Reply #6 on: January 14, 2020, 11:21:02 am »
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Misconception Selection pressures acting on a population cause mutations to occur and thus change the allele frequency of that population
Selection pressures that act on a population do not cause mutations to occur. Mutations occur naturally and randomly. The selection pressures on a population influence which mutations are favourable. For example, temperature may be a selection pressure acting on a population group and thus the alleles that lead to animals having a thick coat to protect them from the cold are more favourable. This means that animals with these alleles (there may be multiple combinations that lead to the same phenotype) are more likely ro survive and reproduce. Over time, favourable alleles will be more likely to be passed on which means the frequency in which alleles are seen in a population changes. In our example, alleles that lead to a thin coat would be seen in fewer and fewer numbers and most of the population would have alleles coding for a thicker coat.

Misconception: Sunlight is a reactant in the process photosynthesis.
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Sine

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Re: Biology Misunderstandings
« Reply #7 on: January 16, 2020, 12:36:44 am »
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Misconception: Sunlight is a reactant in the process photosynthesis.
Interested to see what the misconception is here. Is it the wording sunlight? and the misconception it is that photons are a reactant in photosynthesis. Or are you looking for something like light is a catalyst? (which I don't think is actually the case).

I'll add another misconception for now - feel free to answer laura_'s as well :P
Misconception: B cells originate from bone marrow and T cells originate from the thymus
« Last Edit: January 16, 2020, 12:40:07 am by Sine »

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Re: Biology Misunderstandings
« Reply #8 on: January 16, 2020, 07:21:51 am »
+4
Misconception: B cells originate from bone marrow and T cells originate from the thymus
Nice one Sine! B cells and T cells are actually both produced in the bone marrow (thus, T cells do NOT originate from the thymus). While B cells also mature in the bone marrow, T cells, once produced, travel through the blood stream to the thymus and mature here.

MISCONCEPTION: Natural Selection operates on the genotype of a population.
« Last Edit: January 16, 2020, 07:23:32 am by Chocolatemilkshake »
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Sine

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Re: Biology Misunderstandings
« Reply #9 on: January 17, 2020, 10:11:42 pm »
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MISCONCEPTION: Natural Selection operates on the genotype of a population.
Natural Selection operates on the phenotype of an individual. The phenotype is the physical, biochemical, physiological traits or characteristics of an organism. This phenotype is the expression of an organism's genotype. Natural Selection favours traits (phenotypes) that have a high level of biological fitness - i.e. organisms with these traits are likely to survive to reproductive age and produce offspring.

Misconception: In evolution, the Founder effect and the Bottleneck effect are the same thing

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Re: Biology Misunderstandings
« Reply #10 on: January 20, 2020, 03:01:10 pm »
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Misconception: In evolution, the Founder effect and the Bottleneck effect are the same thing
Couldn't resist answering another one  ;) ;)

The founder effect and the bottleneck effect are both a type of genetic drift (when an allele may become more or less common in a population simply due to chance). However, the bottleneck effect occurs when the size of a population is drastically reduced by a major event, causing the gene pool of future generations to be limited to the alleles of the survivors.

On the other hand, the founder effect occurs when members of a population leave to colonise a new region/area. The gene pool of these founding members may be unrepresentative of the original population and could lead to the new population having drastically different allele frequencies than the population from which the members originated. Unlike in the bottleneck effect, the original gene pool may still survive in the first population, but is now isolated from the new population.

MISCONCEPTION: The coding strand is another name for the template strand of DNA.
« Last Edit: January 20, 2020, 03:03:17 pm by Chocolatemilkshake »
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Re: Biology Misunderstandings
« Reply #11 on: January 26, 2020, 11:28:52 pm »
+3
MISCONCEPTION: The coding strand is another name for the template strand of DNA.
The coding strand and the template strand of DNA are the two different strands of double-stranded DNA. The template strand is the strand of DNA used to transcribe RNA by the enzyme RNA polymerase. The coding strand is the other strand with complementary DNA base pairing to the template strand. It is called the coding strand as the RNA strand produced via transcription has the similar DNA sequence (only different is T is replaced by U).

Misconeption: X-linked recessive disorders/diseases do not ever occur in Females.

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Re: Biology Misunderstandings
« Reply #12 on: January 27, 2020, 12:43:29 pm »
+1
Misconeption: X-linked recessive disorders/diseases do not ever occur in Females.
X-linked recessive disorders are genetic conditions that are carried on the X chromosome. They are recessive, meaning that the dominant allele can mask the condition. In males, there is only one X chromosome, meaning that if the X chromosome they have has the allele for a specific recessive disorder, it will be expressed phenotypically.

Women have two X chromosomes meaning that they require both chromosomes to have the allele for a recessive trait in order for it to be expressed. X-linked recessive conditions can occur in females, but due to the fact that they have two X chromosomes, they are more likely to occur in males (who have a single X) as they cannot be masked by a dominant trait.

Misconception: Sexual reproduction only occurs in animals. Asexual reproduction only occurs in plants.
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Chocolatemilkshake

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Re: Biology Misunderstandings
« Reply #13 on: January 27, 2020, 03:27:36 pm »
+3
Back again for another round...
Misconception: Sexual reproduction only occurs in animals. Asexual reproduction only occurs in plants.

Sexual reproduction can occur in both plants and animals. For example, pollination is a common way in which sexual production occurs in plants. The male gametes from one plant are transferred to the female ovules of another plant via insects or animals. Many plants can both asexually and sexually reproduce.

Likewise, asexual reproduction can occur in both plants and animals. In fact, many animals can undergo both depending on the types of conditions they are living in. This ensures that if a period goes by where they are unable to have contact with other individuals, the species can still survive. For example, the star fish can asexually produce via fragmentation (one of its arms break off and another whole genetically identical star fish is grown from body part) but also produce sexually by the fusing of gametes from two different individuals.

MISCONCEPTION: Each gene can only produce one type of protein.
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Re: Biology Misunderstandings
« Reply #14 on: February 16, 2020, 09:14:35 pm »
+2
MISCONCEPTION: Each gene can only produce one type of protein.
Genes do not produce one specific protein, but rather a family of similar proteins called isoforms. Whilst these proteins are extremely similar, they can have differentiated or even entirely different functions. This is due to alternative splicing as when the DNA is transcribed, some extrons may be spliced out along with the introns, creating a different variety of the same protein.

MISCONCEPTION: Golgi bodies, endoplasmic reticulum, mitochondria and ribosomes are all never visible under a light microscope.
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