BIOLOGY

Question 1

What is essential for diffusion?

Answer 1

A concentration gradient is necessary for diffusion. This is the process by which particles move from areas of higher concentration to areas of lower concentration. If there is less of a substance on one side of the membrane some of it will be able to diffuse through. Energy is not needed for diffusion to occur. In cells, some materials can pass directly through the phospholipid membrane, while others need a protein channel.

Question 2

Convert 6 mm to um.

Answer 2

6mm = 6000u

Question 3

Put in order from smallest to largest: cell membrane, E coli bacterium, HIV virus, human heart cell

Answer 3

Cell membrane, virus, bacteria, heart cell

Question 4

What structures would you find in both a plant and animal cell?

Answer 4

Both plant cells and animal cells have the following: a nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, ribosomes, vacuoles, and vesicles

Question 5

Calculate the magnification of a cell with a length of 15 um that is drawn 100 mm big

Answer 5

Magnification = image size/specimen size = 100000um/15um = about 6700x

Question 6

List as many monosaccharides as you can think of.

Answer 6

Ribose, glucose, galactose, fructose

Question 7

What is the process when monomers join and what is the process when polymers break?

Answer 7

The former is condensation, the latter is hydrolysis.

Question 8

Describe how a phagocyte digests a pathogen.

Answer 8

Phagocytes digest pathogens with a process called phagocytosis. A pathogen is absorbed into the phagocyte through endocytosis. In the body, it is digested in a lysosome. The remains are expelled through exocytosis.

Question 9

Describe the primary, secondary, tertiary, and quaternary of a protein.

Answer 9

The primary structure is the order of amino acids in a polypeptide. The secondary structure describes how the polypeptide folds in distinct patterns based on the hydrogen bonds; either alpha helices or beta pleated sheets are formed. The tertiary structure is the general three-dimensional shape based on the interactions between different R-groups of the amino acids. The two main types are globular and fibrous (elongated) or globular (rounded). The quaternary structure described how the polypeptide interacts with other polypeptides or other materials called prosthetic groups.

Question 10

What is the composition of the backbone of DNA?

Answer 10

The backbone of DNA consists of nucleotides. They consist of a pentose sugar, a phosphate group, and one of four nitrogenous bases.

Question 11

What type of bond joins hydrogen and oxygen within a water moc? Joins nitrogenous bases?

Answer 11

The atoms in a water molecule are joined with covalent bonds. Nitrogenous bases from different nucleotides are joined via hydrogen bonding.

Question 12

What is a nucleosome?

Answer 12

Nucleosomes are how DNA is stored. Each nucleosome consists of eight histone proteins with DNA wrapped around. Many nucleosomes together allow the DNA to be supercoiled.

Question 13

What are the functions of the enzymes in DNA replication?

Answer 13

Helicase - breaks the hydrogen bonds in DNA so the two strands separate
Girase - ensures the area outside the replication fork (where the DNA opens up) does not supercoil
RNA primase - adds RNA primers to the DNA strands so that the polymerase has a location to start
Polymerase III - adds new nucleotides to the DNA strands
Polymerase I - Replaces RNA primers with DNA and looks for mistakes in the replication
Ligase - connects Okazaki fragments on the lagging strand

Question 14

Where do transcription and translation occur?

Answer 14

Transcription occurs at the DNA, in the nucleus of the cell. Translation occurs at ribosomes, which exist in the cytoplasm and along the rough endoplasmic reticulum.

Question 15

What is removed to create mature mRNA?

Answer 15

In eukaryotic cells, before the mRNA leaves the nucleus, introns are removed to make mature mRNA.

Question 16

What is a codon and an anticodon?

Answer 16

A codon is a trio of nitrogenous bases that code for a specific amino acid when transcribed. Anticodons are the trio of nucleotides in tRNA that have the complimentary base pairs for a specific codon so that when they match during translation the amino acid bound to the tRNA will join the polypeptide chain.

Question 17

What can you tell from a karyogram?

Answer 17

A karyogram displays all of an organism’s chromosomes. This can show the gender of the subject and if they have any genetic conditions caused by too many or not enough chromosomes, such as Down Syndrome.

Question 18

What is the difference in cytokinesis of plant and animal cells?

Answer 18

In plants, a cell plate is formed between the two nuclei, which becomes new cell walls. In animal cells, the cell membrane pinches between the two nuclei, creating a cleavage furrow and eventually separating the two daughter cells.

Question 19

What constitutes a linkage group?

Answer 19

A linkage group is a group of genes that are all on the same chromosome. The genes on these chromosomes do not assort independently; that is, every organism has only two combinations of all of the alleles present on the chromosome which they can pass on to offspring. The only exception is if any crossing over occurs.

Question 20

What are homologous chromosomes?

Answer 20

Homologous chromosomes are chromosomes which have the same genes but not necessarily the same alleles for these genes.

Question 21

How are biotechnology and lactose free milk related?

Answer 21

Biotechnology companies can be immobilized; this allows them to exist and function outside a living organism and in specific conditions. The companies can immobilise lactase, the enzyme that digests lactose, in alginate beads. When milk is passed past the beads, the lactose is broken down into glucose and galactose, making the milk lactose-free and safe for people with lactose-intolerance.

Question 22

What does the genotype X^H X^h indicate?

Answer 22

X is a sex chromosome, and two X chromosomes signify that this person is female. The H represents the allele for having hemophilia; it is a sex-linked trait on the X chromosome. It is also a recessive trait, meaning that one would need two recessive (h) alleles to have the trait. This female has one dominant allele (H) and one recessive allele (h), so she does not have hemophilia.

Question 23

How can you determine genotypes from a pedigree chart?

Answer 23

On a pedigree chart, the symbols for people who have the recessive trait are coloured with one colour, those for people with the dominant trait when it is unknown if they are heterozygous or homozygous are coloured with another colour, and those for people who are definitely heterozygous are coloured with both colours. It is impossible to conclude with complete certainty that someone is homozygous dominant using a pedigree chart.

Question 24

Where would you find the largest pieces of DNA on a gel?

Answer 24

The largest pieces of DNA would be near the top of the gel. Their large size makes it harder to navigate through the gel so they do not travel as far.

Question 25

What does the digestion of starch by amylase produce?

Answer 25

Amylase breaks down amylose (or starch) into monomers and smaller polymers, either maltose or malotriose.

Question 26

Is this sequence of blood flow correct in the human heart? Right ventricle –> pulmonary veins –> aorta

Answer 26

This is not correct. The order is, starting from the lungs: pulmonary veins, left atrium, left ventricle, aorta.

Question 27

How do endocrine glands differ from exocrine glands?

Answer 27

Both kinds of glands secrete hormones; the difference is where the substances are secreted. Endocrine glands secrete material directly into the bloodstream; while hormones from exocrine glands are secreted through a specific duct.

Question 28

What is the central canal in a villus called and what is its function?

Answer 28

The central canal of a villus is called the lacteal. Lacteals absorb and transport lipids, which cannot be absorbed into the capillaries like vitamins, carbohydrates, and other materials.

Question 29

Which vessel directly supplies the heart muscle with blood?

Answer 29

The muscles in the heart are supplied blood with the coronary arteries.

Question 30

What is the name of the tube that branches into the trachea and esophagus?

Answer 30

This tube is called the pharynx.

Question 31

Which muscles contract for exhalation?

Answer 31

When exhaling, the internal intercostal muscles contract.

Question 32

What is binary fission?

Answer 32

Binary fission is the reproductive process of prokaryotic cells; it involves the replication of DNA and the division of cytoplasm.

Question 33

What is a centromere?

Answer 33

This is the point on a chromosome where the two sister chromatids are connected; the spindle fibres attach here as well.

Question 34

What is movement against a concentration gradient?

Answer 34

In order to move against the concentration gradient, substances need to move via active transport.

Question 35

What is a biological catalyst called?

Answer 35

A biological catalyst is called an enzyme.

Question 36

What is the difference between phenotype and genotype?

Answer 36

A phenotype is the actual trait or characteristic that an organism possesses, while the genotype is the specific alleles that the organism has that led to the trait.

Question 37

What are a group of ribosomes moving along the same mRNA molecule called?

Answer 37

This is called a polysome.

Question 38

What are the pneumocytes and what do they do?

Answer 38

Pneumocytes are cells that make up the alveoli. Type I pneumocytes are very thin cells that make up the epithelium of the alveoli; their thin width makes the transfer of gases between the alveoli and the capillaries fast and easy. Type II pneumocytes secrete a fluid in the inner surface of alveoli that serves as a pulmonary surfactant to reduce surface tension in the alveoli and prevents them from sticking together. It also allows the oxygen to dissolve and carbon dioxide to evaporate into exhaled air.

Question 39

What is the interior of an artery or a vein called? How are they different?

Answer 39

The inside of an artery or vein is called the lumen. The lumen of arteries is smaller but the walls are very thick to support the pressurized blood. In veins there is less pressure so the lumen can be larger; it also has valves so that the blood can flow against the force of gravity.

Question 40

What two circuits make up the human circulatory system?

Answer 40

There are two circuits of the circulatory system: the pulmonary circuit (in which deoxygenated blood travels from the heart to the lungs for gas exchange and then returns to the heart with oxygen) and the systemic circuit (in which oxygenated blood leaves the heart to provide oxygen to the rest of the body and returns to the heart deoxygenated).

Question 41

What is systole and diastole?

Answer 41

The systole is the phase of a heartbeat when the muscles are contracted and blood is sent into the arteries. The diastole is the other phase in which the heart muscles are relaxed and blood flows into the heart from the veins.

Question 42

What controls heartrate?

Answer 42

Heart rate is controlled by the sinoatrial node in the heart and two nerves from this node to the brain. The sinoatrial node sends out electric signals to the muscles of the heart to make certain muscles contract, and the two different nerves can send neurotransmitters to the node to instruct it to send the electric signal more or less often.

Question 43

Where is the sinoatrial node and what is it for?

Answer 43

The sinoatrial node is in the right atrium of the heart. Its function is to control heart rate by sending signals to the heart muscles to contract.

Question 44

What are the names of diseases we studied and what causes them?

Answer 44

Atherosclerosis (occlusion of coronary arteries) - development of fatty tissue in the walls of coronary arteries which reduces blood flow to the heart
Lung cancer - caused by the inhalation of chemicals, such as cigarette smoke, air pollution, and asbestos particles
Emphysema - a disease in which the thin walls of the alveoli are replaced with thicker sacs so gas exchange is more difficult because the surface area is reduced and distance of diffusion is greater; it is caused by an increase in the activity of an enzyme that can digest lung tissue, possible caused by smoking.

Question 45

How does a villus function to do its job?

Answer 45

Villi absorb monomers, vitamins, and mineral ions. They give the walls of the small intestine a very high surface area so a lot of materials can be absorbed at once. Lipids which are non-polar have to pass through a special tube called a lacteal, while other substances can enter the bloodstream through the capillaries in the villi. Depending on the material different methods are used to leave through the epithelial cells of the villi, such as simple diffusion, facilitated diffusion, active transport, and exocytosis.

Question 46

What are the parts of a Paramecium?

Answer 46

The major parts of a paramecium are as follows:
Pellicle - the exterior membrane of the paramecium
Contractile vacuoles - store and expel water through radiating canals
Macronucleus - location of genetic material and area that controls all metabolic processes
Micronucleus - another area with genetic material; contains genetic material required for sexual reproduction
Oral groove - where food enters the paramecium
Cytosome - the division between the oral groove and gullet
Gullet - path of the food before it is stored in a food vacuole
Food vacuole - stores food for the paramecium to use later
Cilia - small hairs all around the paramecium used for movement
Cytopyge - where waste is expelled
Trichocysts - the bases of the cilia
Cytoplasm - the fluid containing all other parts of the paramecium; consists of ectoplasm (thicker exterior) and endoplasm (thinner interior)

Question 47

Where does transcription start in DNA?

Answer 47

Transcription starts at a start codon. This is a codon that will code for methionine. The RNA polymerase identifies this region with the help of the promoter region.

Question 48

What conditions are sex linked (or X-linked in humans?)

Answer 48

ALD
Colourblindness
Hemophilia
Tortoiseshell colouring in cats

Question 49

What are the steps to showing your work in a genetics problem?

Answer 49

Step 1: Give the genotypes symbols - uppercase letter for dominant and lowercase for recessive
Step 2: Identify the genotypes of the parents
Step 3: Identify what gamete or combination of gametes they can provide to an offspring
Step 4: Make a Punnet grid to cross over all possible gametes from the two parents
Step 5: Use the results of the Punnet grid to find the genotype and phenotype ratios

Question 50

How do inhalation and exhalation work?

Answer 50

In the process of inhalation, the external intercostal muscles contract, and the diaphragm contracts, pushing downwards. This increases the volume of the chest cavity, which reduces the pressure. Gases move from areas of high pressure to areas of lower pressure, so gases in the air enter the lungs. Alternatively, when exhaling, the internal intercostal muscles contract, and the diaphragm relaxes so it moves back up. This reduces volume and increases the pressure in the lungs, so the air moves out.

Question 51

What are the steps in mitosis?

Answer 51

Prophase - DNA supercoils into chromosomes and the nuclear membrane dissolves
Metaphase - spindle fibres at either pole pull chromosomes to middle of cell
Anaphase - spindle fibres separate sister chromatids and pull them to either side of the cell
Telophase - chromosomes uncoil back into chromatin and two new nuclear membranes reform

Question 52

What are the steps in meiosis?

Answer 52

Prophase 1 - DNA supercoils into chromosomes and the nuclear membrane dissolves; homologous chromosomes stay together
Metaphase 1 - spindle fibres line up chromosomes in two rows in the middle of the cell; homologous pairs are parallel to each other but the order is random
Anaphase 1 - spindle fibres separate the homologous pairs and they are pulled to opposite sides of the cell
Telophase 1 - chromosomes uncoil back into chromatin and nuclear membranes reform
(Cytokinesis occurs in between as well; the cell completely divides into two separate cells)
The steps for prophase 2 - telophase 2 are the same as those for the steps of mitosis; see above

Question 53

What are the steps in DNA replication?

Answer 53

Helicase breaks the hydrogen bonds between DNA strands and unwinds it
DNA gyrase prevents the area outside the replication fork from supercoiling.
Single-stranded binding proteins prevent the hydrogen bonds from reforming between the strands
RNA primase adds short lengths of RNA to the strands so that the DNA polymerase III has a place to start
DNA polymerase III adds nucleotides in a 5’ to 3’ direction based on complimentary base pairing; therefore on one strand the replication is continuous but on the opposite it has to build backwards, creating segments between primers called Okazaki fragments
DNA polymerase I replaces the primers with DNA and looks for any mistakes in the replication to correct
DNA ligase connects the Okazaki fragments

Question 54

What are the steps in transcription?

Answer 54

RNA polymerase binds to the start codon on the antisense strand of DNA, based on signals from the promoter
The RNA polymerase binds RNA nucleotides based on complimentary base pairing until it reaches a stop codon
When the stop codon is reached, the mRNA strand detaches from the DNA strand and the DNA recoils
In eukaryotic cells introns (regions of mRNA not for coding) are removed from the strand and the remaining parts are spliced back together

Question 55

What are the steps in translation?

Answer 55

Initiation: The small and large subunits of the ribosome, the mRNA, and a tRNA molecule carrying the start codon amino acid methionine all bind together; the tRNA is in the P site
Elongation: This process occurs repeatedly: The ribosome moves along the mRNA strand, and new tRNA molecules bind to the A site, then to the P site where their amino acid is bonded to the existing chain, then to the E site where it leaves; the process is continuous so there is tRNA in the P and A sites at one time
Termination: When the ribosome reaches the stop codon, all the components unbind and the polypeptide forms

Question 56

What are the details of sickle cell anemia?

Answer 56

Sickle-cell anemia is caused by a single base substitution mutation. The sixth codon on the antisense strand in the region of DNA that codes for one of the hemoglobin polypeptides is changed from GAG to GTG. This results in the coding of valine instead of glutamic acid. This small change effects the final protein greatly; hemoglobin molecules can stick together, which distorts the shape of the red blood cells. The cells can get stuck in capillaries, and the change in shape can damage the plasma membranes so that they do not last as long. This gives people anemia as well as other health problems.

Question 57

What do you call the pressure when the heart (ventricles) contract? Relax?

Answer 57

The pressure when the heart contracts is called systolic pressure. The pressure when the heart is relaxed is called diastolic pressure.

Question 58

Describe the process of translation

Answer 58

translation is the synthesis of proteins/polypeptide chain/specific sequence of amino acids;
translation occurs in cytoplasm/ribosomes;
uses information on the mRNA
mRNA carries the genetic information of DNA;
mRNA binds to ribosome;
mRNA contains series of codons/base triplets;
tRNA binds with an amino acid and carries it to the ribosome;
tRNA has the anticodon that is complementary to the codon on the mRNA;
two tRNAs bind to a ribosome/mRNA at the same time;
(peptide) bond forms between to amino acids (carried by tRNA molecules to the ribosome);
the first tRNA detaches, ribosome moves along mRNA and another tRNA carrying an amino acid binds;
process repeats forming chain of amino acids/polypeptides

Question 59

Explain how the structure of the villus in the small intestine is related to its function

Answer 59

the villus has a large surface area to volume ratio;
microvilli increase surface area for absorption;
thin surface (epithelial) layer so products of digestion can pass easily through;
channel proteins located in plasma membrane used for facilitated diffusion;
network of capillaries inside each villus (so only short distance) for movement of absorbed products
capillaries transport absorbed nutrients/sugars and amino acids away from small intestine;
blood flow in capillaries maintains concentration gradient;
central lymph vessel/lacteal to transport absorbed fats/fatty acids away from small intestine;
large number of mitochondria provide ATP needed for active transport;
protein pumps in membrane (of microvilli) carry out active transport;
pinocytosis occurs at surface (epithelial) layer;

Question 60

Describe the structure of the ventilation system in humans, including the alveoli

Answer 60

ventilation occurs within the lungs;
trachea divides to form two bronchi;
bronchi divide to form bronchioles;
several divisions of bronchioles;
alveoli connected to bronchioles;
trachea/bronchi/bronchioles/airways lined with cilia/ciliated epithelium;
diaphragm and intercostal muscles;
trachea/bronchi have rings/c-shaped pieces of cartilage;
alveolus is an (air) sac;
very small / diameter is about 100 um;
there are many alveoli so there is a large total surface area;
wall of alveolus is a single layer of cells;
cells in alveolus wall are very thin;
surrounded by a network of capillaries;
some larger cells in the wall sercrete fluid/natural detergent

Question 61

Discuss sickle cell anemia

Answer 61

one codon in the DNA is altered,
mRNA with one altered base/codon
GAG –> GUG in mRNA / CTC –> CAC in DNA / GAG –> GTG in DNA;
different tRNA binds to this codon;
different amino acid inserted into the polypeptide;
glutamic acid –> valine;
structure of the polypeptide / protein is altered;
active site of an enzyme may not function;
altered hemoglobin may cause red cells to become sickle shaped;
single proteins can have vital roles within the body;
details of symptoms of sickle cell anemia

Question 62

Discuss surface area as it relates to the human body

Answer 62

As a cell grows, its volume increases faster than its surface area, so it must divide or it will not be able to absorb enough nutrients and oxygen to service the entire volume of the cell;
villi and microvilli in the small intestine increases surface are for nutrient absorption;
small intestine is long (6 m) increasing surface area for nutrient absorption;
millions of alveoli in each lung increase surface area in the lung for absorption of oxygen and getting rid of carbon dioxide;
bile from the gall bladder emulsifys fat in the duodenum creating more surface area for digestion by lipase;