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
The Correct Answer is 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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
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. In a physical change, the atoms and molecules of the substance are rearranged, but no new substances are formed.
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.
Correct Answer is B
Explanation
The epididymis is a coiled tube located at the back of each testicle where the sperm mature and are stored until ejaculation. Sperm are produced in the testes and then transported to the epididymis where they undergo maturation and become motile. The epididymis provides a protective environment for the sperm, allowing them to mature and become more resilient to external stressors. During ejaculation, the sperm is transported from the epididymis to the vas deferens and then to the urethra for ejaculation.
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