What is the name of the genetic disorder caused by the presence of an extra chromosome 21?
Turner syndrome
Klinefelter syndrome
Down syndrome
Huntington's disease
Correct Answer : C
Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is also known as trisomy 21, because affected individuals have three copies of chromosome 21 instead of the normal two.
The extra chromosome 21 in Down syndrome occurs due to a random error in cell division, which leads to the production of an abnormal gamete (egg or sperm) with an extra copy of the chromosome. When this gamete fuses with a normal gamete during fertilization, the resulting zygote has 47 chromosomes instead of the usual 46, and develops into a fetus with Down syndrome.
Down syndrome is characterized by a range of physical and intellectual symptoms, including developmental delays, intellectual disability, distinctive facial features, heart defects, and increased risk of certain medical conditions such as leukemia and Alzheimer's disease. However, the severity and expression of these symptoms can vary widely among affected individuals.
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Correct Answer is C
Explanation
Innate immunity is a fundamental aspect of the body's defense mechanism that operates from birth. It offers immediate protection against a wide range of pathogens, such as bacteria, viruses, and fungi, without requiring prior exposure to these invaders.
This defense system is non-specific, meaning it doesn't target a particular pathogen but rather provides a generalized response to various threats. Innate immunity includes physical barriers like the skin and mucous membranes, as well as cellular components such as phagocytes and natural killer cells. These elements work together to detect and neutralize potential threats swiftly, preventing infections from taking hold in the body.
Correct Answer is A
Explanation
The nurse can logically conclude that:
✅ Treatment A results in the shortest recovery time.
- The data shows that Treatment A has a mean recovery time of 3 days, which is the shortest compared to Treatment B (5 days) and Treatment C (7 days).
The other statements are not supported by the given data:
❌ "Treatment C enhances patient satisfaction more than the others."
- There is no information about patient satisfaction, only recovery times.
❌ "Treatment B is as effective as Treatment A."
- Treatment B has a longer recovery time (5 days) compared to Treatment A (3 days), so it is not equally effective in terms of recovery speed.
❌ "Treatments A and B provide the same rate of recovery."
- Treatment A has a faster recovery time than Treatment B, so they do not have the same recovery rate.
Correct Answer is B
Explanation
The mitral valve is located between the left atrium and left ventricle of the heart and helps to regulate the flow of blood between these chambers. It consists of two leaflets or flaps that open and close in response to changes in pressure as the heart beats.
During diastole, when the heart is relaxed and filling with blood, the mitral valve opens to allow blood to flow from the left atrium into the left ventricle. During systole, when the heart contracts to pump blood out of the left ventricle and into the systemic circulation, the mitral valve closes to prevent backflow of blood into the left atrium.
The mitral valve is one of four valves in the heart that help to ensure the unidirectional flow of blood through the heart and the rest of the circulatory system. Problems with the mitral valve, such as mitral valve prolapse or mitral stenosis, can lead to a range of symptoms and complications, including shortness of breath, fatigue, chest pain, and heart failure.
Correct Answer is A
Explanation
The three germ layers that form during embryonic development are the ectoderm, mesoderm, and endoderm. The ectoderm is the outermost layer, and it gives rise to the skin, hair, nails, and nervous system. The nervous system develops from a specialized region of the ectoderm called the neural plate, which invaginates to form the neural tube. The neural tube ulmately gives rise to the brain and spinal cord, which make up the central nervous system, as well as the peripheral nervous system. The endoderm gives rise to the lining of the digesve and respiratory tracts, while the mesoderm gives rise to the musculoskeletal system, circulatory system, and several other organs. The exoderm is not a germ layer and does not exist during embryonic development.
Correct Answer is C
Explanation
The three major pairs of salivary glands are the parod glands, sublingual glands, and submandibular glands. The parotid glands are located just in front of your ears. The sublingual glands are below either side of your tongue, under the floor of your mouth. The submandibular glands are located below your jaw ¹.
Correct Answer is B
Explanation
Transcription is the process by which DNA is copied into RNA. During transcription, the DNA molecule unwinds and RNA polymerase reads the DNA sequence and synthesizes a complementary RNA molecule using the DNA as a template.
Correct Answer is C
Explanation
- The number of protons in an atom is equal to its atomic number.
- The periodic table shows that phosphorus (P) has an atomic number of 15.
- This means every phosphorus atom has 15 protons in its nucleus.
Analysis of Other Options:
- A. 30 → This is close to the atomic mass (30.97), but the atomic mass is not the same as the number of protons. ❌
- B. 16 → This is incorrect; sulfur (S) has an atomic number of 16, not phosphorus. ❌
- D. 31 → This is rounded from the atomic mass (30.97), but atomic mass ≠ number of protons. ❌
Correct Answer is A
Explanation
The main difference between a solid and a liquid is their physical state and the way their particles are arranged. In a solid, the particles are tightly packed together and have a fixed position, which gives the solid a definite shape and volume. Solids are also characterized by their high density, low compressibility, and high thermal conductivity.
In contrast, the particles in a liquid are more loosely packed and can move around each other, which allows the liquid to take the shape of its container. Liquids have a definite volume but no fixed shape, which means they can be poured or spilled. Liquids also have a lower density than solids, are more compressible than solids, and have lower thermal conductivity than solids.
Option b) is incorrect because it describes the properties of a gas, not a liquid. Option c) is incorrect because solids and liquids have different physical properties. Option d) is incorrect because it describes the properties of a gas, not a liquid or a solid.
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Correct Answer is A
Explanation
The chemical formula for water is H2O. It consists of two hydrogen atoms and one oxygen atom.
Correct Answer is A
Explanation
A physical change is a change that affects the physical properties of a substance, but does not change its chemical identity. Physical changes include changes in state, such as melting or boiling, changes in shape or size, and changes in phase, such as the dissolution of a solid in a liquid.
A chemical change, on the other hand, is a change that results in the formation of new substances with different chemical properties. Chemical changes involve the breaking of chemical bonds between atoms and the formation of new bonds to create new compounds. Chemical changes are usually accompanied by a change in color, the formation of a gas or a solid, or the release or absorption of energy.
Overall, the main difference between a physical change and a chemical change is that a physical change only affects the physical properties of a substance while a chemical change results in the formation of new substances with different chemical properties.
Note:Choice B is partially cirrect since physical changes can involve changes in the state of matter (e.g., ice melting into water), but it's not the main characteristic. A chemical change typically involves the change of one substance into another with different chemical properties.
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