The Ultimate Biology Exam For Students! Quiz

Hemophilia is a sex-linked genetic disorder because it is caused by a mutation on the X chromosome. Since males only have one X chromosome, if they inherit the mutated gene, they will develop hemophilia. Females, on the other hand, have two X chromosomes, so even if they inherit the mutated gene on one chromosome, they have a second healthy X chromosome that can compensate for the mutation. Therefore, hemophilia primarily affects males and is inherited from carrier females.

Kary Mullis is the correct answer because he is the scientist who developed the PCR technique. PCR, or polymerase chain reaction, is a method used in molecular biology to amplify a specific segment of DNA. Mullis's invention of PCR in 1983 revolutionized the field of genetics and has since become a fundamental tool in various areas of biological research and diagnostics.

High titres of antinuclear antibodies are indicative of autoimmune diseases. Antinuclear antibodies are produced by the immune system when it mistakenly targets the body's own cells and tissues. These antibodies specifically target the nucleus of cells, hence the name. In autoimmune diseases, the immune system mistakenly identifies normal cells as foreign and attacks them, leading to inflammation and tissue damage. The presence of high levels of antinuclear antibodies suggests an overactive immune response and is commonly seen in autoimmune conditions such as lupus, rheumatoid arthritis, and Sjögren's syndrome.

PCR (Polymerase Chain Reaction) is a technique used to amplify and make multiple copies of a specific DNA sequence. It is a powerful tool in molecular biology and has several characteristics. Firstly, PCR can synthesize billions of copies of desired DNA from microgram quantities of DNA. This allows researchers to work with small amounts of DNA samples. Secondly, automated PCR machines, known as thermal cyclers, are used to carry out the PCR process efficiently and accurately. Lastly, a thermostable DNA polymerase, such as Taq polymerase, is required for PCR as it can withstand the high temperatures needed for DNA denaturation and synthesis. Therefore, all of the given statements are true regarding PCR.

Sickle cell disease is so called because pH changes in the blood cells cause them to collapse into a sickle shape. This abnormal shape of the red blood cells leads to various health complications, such as reduced oxygen flow and blockage of blood vessels, causing pain and organ damage. The name "sickle cell" refers to the characteristic sickle or crescent shape of the red blood cells in individuals with this disease.

The cones of the retina are responsible for color vision. Unlike rods, which are more numerous and are responsible for low-light and black-and-white vision, cones are specialized for detecting different colors. They contain red, blue, and green light-sensitive pigments that differ due to variations in the retinal prosthetic group. Cones play a crucial role in our ability to perceive and distinguish different colors in our visual environment.

Deletion is the chromosomal alteration that would have the most drastic consequences. Deletion refers to the loss of a segment of DNA from a chromosome. This can result in the loss of important genetic information, leading to a range of potential effects such as the disruption of gene function, loss of genetic diversity, and potential developmental abnormalities. In contrast, inversion, duplication, and translocation involve rearrangements of genetic material but do not result in the loss of genetic information to the same extent as deletion.

Cystic fibrosis is the most common lethal genetic disease in the United States. It is a hereditary disorder that affects the lungs, digestive system, and other organs. It is caused by a mutation in the CFTR gene, which leads to the production of thick, sticky mucus that clogs the airways and obstructs the pancreas. This can result in respiratory infections, difficulty breathing, poor growth, and digestive problems. While sickle-cell anemia, Huntington's disease, and hemophilia are also genetic diseases, cystic fibrosis is the most prevalent and deadly in the United States.

The correct answer is "all of the above". ATP concentration is maintained relatively constant during muscle contraction by increasing the metabolic activity, which produces more ATP. Additionally, creatine phosphokinase helps regenerate ATP from ADP and creatine phosphate, while adenylate kinase helps transfer a phosphate group from one ADP molecule to another, forming ATP. Therefore, all three mechanisms work together to maintain ATP levels during muscle contraction.

The correct answer is Taq polymerase. Taq polymerase is derived from the thermophilic bacterium Thermus aquaticus, commonly known as musaquaticus. It is a heat-stable enzyme that is widely used in polymerase chain reaction (PCR) to amplify DNA. Taq polymerase is able to withstand high temperatures, making it ideal for PCR, which involves repeated cycles of heating and cooling. It is an essential tool in molecular biology research and has revolutionized the field of genetics.

The probability of their next child being born with alkaptonuria is 1/4. This is because alkaptonuria is an inherited disorder, which means it is caused by a specific gene mutation that is passed down from parents to their children. If both Ram and Nidhi are carriers of the gene mutation (meaning they have one normal copy of the gene and one mutated copy), there is a 25% chance that their next child will inherit two copies of the mutated gene and therefore be born with alkaptonuria.

The correct answer is sarcomere. The sarcomere is the functional unit of the contractile system in striated muscle. It is the basic structural and functional unit of muscle contraction. It is composed of overlapping thick and thin filaments, which slide past each other during muscle contraction, causing the muscle to shorten. The sarcomere is bordered by Z bands and contains the myofibrils, which are responsible for muscle contraction. Cross bridges are the connections formed between the thick and thin filaments within the sarcomere during muscle contraction.

A recombination frequency of 5 percent is equal to 5 centimorgans. Recombination frequency is a measure of the likelihood of two genes being separated during the process of genetic recombination. One map unit is equal to 1 percent recombination frequency, so 5 percent recombination frequency would be equivalent to 5 map units or 5 centimorgans.

CD40 ligand is seen only on Helper T cells. This means that Helper T cells express CD40 ligand on their surface. CD40 ligand is a protein that plays a crucial role in the immune response by interacting with CD40 receptors on other immune cells, such as B cells and dendritic cells. This interaction is important for the activation and differentiation of these cells, leading to a coordinated immune response. Macrophages, cytotoxic T cells, and dendritic cells do not express CD40 ligand on their surface.

A heritable feature refers to a specific characteristic that can be passed down from one generation to another through genes. This characteristic can have two or more different variations, which are known as traits.

An exon is the correct answer because it is a section of DNA that contains the coding sequence for a protein. Exons are transcribed into mRNA and then translated into a protein. In contrast, introns are non-coding sequences that are spliced out during mRNA processing, regulatory sequences control gene expression, and "non-of these" is not a valid option.

Helper T cells are a type of white blood cell that play a crucial role in the immune response. They function in both cell-mediated and hormonal responses, meaning they help coordinate the actions of other immune cells and also release chemical messengers to regulate immune activity. Helper T cells bear surface CD4 molecules, which are important for their interaction with other immune cells. However, they are not activated by polysaccharide fragments. Instead, they are primarily activated by the presentation of antigens by antigen-presenting cells.

PCR (Polymerase Chain Reaction) is a technique used in molecular biology to amplify a specific segment of DNA. It can be used for various purposes, including DNA degradation, amplification, and sequencing. Therefore, the correct answer is "all of these" as PCR can be used for all of these techniques.

Chromium is the mineral element that facilitates insulin binding to cell receptor sites. Insulin is a hormone that helps regulate blood sugar levels, and chromium plays a crucial role in enhancing insulin sensitivity and promoting its action. It helps insulin attach to the receptors on cell membranes, allowing glucose to enter the cells and be used for energy. Chromium deficiency can lead to insulin resistance and impaired glucose metabolism, which may contribute to the development of conditions like diabetes. Therefore, chromium is essential for proper insulin function and glucose regulation in the body.

Taq polymerase is not thermostable, unlike the other three polymerases mentioned. This means that Taq polymerase is not able to withstand high temperatures, which is a crucial characteristic for polymerases used in techniques such as PCR that require high-temperature cycling. In contrast, Vent polymerase, DNA polymerase III, and pfu polymerase are all known for their ability to function at high temperatures without denaturing, making them suitable for applications that involve high-temperature reactions.