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 A
Explanation
Innate immunity and adaptive immunity are two arms of the immune system that work together to protect the body from pathogens. Innate immunity is the first line of defense and is present at birth. It includes physical and chemical barriers such as the skin, mucous membranes, and antimicrobial peptides, as well as cells such as macrophages and natural killer cells that can quickly recognize and atack pathogens. Innate immunity is nonspecific, meaning it responds to a wide variety of pathogens in a similar way.
Adaptive immunity, on the other hand, is acquired after exposure to pathogens. It involves the production of antibodies and activation of T cells, which are specific to particular pathogens. Adaptive immunity takes longer to develop than innate immunity, but it provides a more specific and targeted response to pathogens. Once the adaptive immune system has been activated against a particular pathogen, it can provide long-term protection against future infections with that pathogen.
Option b) is incorrect because innate immunity is nonspecific while adaptive immunity is specific. Option c) is incorrect because antibodies are a part of adaptive immunity while T cells can be a part of both innate and adaptive immunity. Option d) is incorrect because adaptive immunity can provide long-term protection, while innate immunity provides immediate but short-lived protection.
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Correct Answer is A
Explanation
Chlorophyll a is the primary pigment responsible for photosynthesis in plants. It is a green pigment that is essential for capturing light energy from the sun and converting it into chemical energy that can be used by the plant. Chlorophyll a absorbs light most efficiently in the blue and red parts of the spectrum, and reflects green light, giving plants their characteristic green color
Chlorophyll b is another type of chlorophyll that is also involved in photosynthesis, but it is not as abundant as chlorophyll a. Chlorophyll b absorbs light most efficiently in the blue and orange parts of the spectrum and reflects yellow-green light.
Carotenoids are pigments that are present in many plants and are involved in photosynthesis as well as protecting the plant from damage caused by excess light. Carotenoids are responsible for the orange, yellow, and red colors of many fruits and vegetables.
Anthocyanins are pigments that give plants their red, purple, and blue colors. While they are not directly involved in photosynthesis, they play a role in atracting pollinators and protecting the plant from damage caused by UV radiation.

Correct Answer is C
Explanation
A frameshift mutation is a type of genetic mutation that involves the insertion or deletion of one or more nucleotides in a DNA sequence. This can cause a shift in the reading frame of the genetic code, resulting in a change in the amino acid sequence of the resulting protein. Frameshift mutations can have significant effects on the function of the protein and can lead to genetic disorders or diseases.
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 A
Explanation
Transfer RNA (tRNA) is responsible for carrying amino acids to ribosomes during protein synthesis. Each tRNA molecule has a specific ancodon that matches a codon on the messenger RNA (mRNA) molecule. The tRNA molecule binds to the mRNA codon and brings the corresponding amino acid to the ribosome, where it is added to the growing polypepde chain.

Correct Answer is A
Explanation
The data collected by the researcher on the number of cars passing through a busy intersection at different times of the day for a month would be most useful to analyze traffic patterns during rush hour.
Correct Answer is B
Explanation
- Lithium (Li) is a metal from Group 1 (alkali metals) on the periodic table.
- Bromine (Br) is a nonmetal from Group 17 (halogens).
- When a metal reacts with a nonmetal, an ionic bond forms, resulting in an ionic compound.
- Lithium donates one electron to bromine, forming Li⁺ (cation) and Br⁻ (anion), which attract each other to form LiBr (Lithium Bromide).
Analysis of Other Options:
- A. Coordinate compound → Involves a metal ion bonded to a ligand via coordinate (dative) bonds, not relevant here. ❌
- C. Organic compound → Organic compounds contain carbon, but LiBr does not. ❌
- D. Covalent compound → Covalent bonds occur between two nonmetals, but lithium is a metal. ❌
Correct Answer is C
Explanation
Osmosis is the process by which water molecules move across a selectively permeable membrane from an area of high concentration to an area of low concentration, in order to equalize the concentration of solutes on both sides of the membrane. Selectively permeable membranes allow only certain molecules to pass through, while preventing the passage of others.
In osmosis, the movement of water molecules is driven by the concentration gradient of solutes, which cannot pass through the membrane. If one side of the membrane has a higher concentration of solutes
than the other, water molecules will move from the side with the lower concentration of solutes to the side with the higher concentration of solutes, in an atempt to dilute the solutes and equalize the concentration on both sides.
Osmosis is important in many biological processes, including the uptake of water by plant roots, the regulation of water balance in animal cells, and the preservation of food by adding salt or sugar to create a hypertonic environment that inhibits bacterial growth.
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Correct Answer is B
Explanation
Carbohydrates are one of the main types of biomolecules and are composed of monomers called monosaccharides. Monosaccharides are simple sugars that cannot be further broken down into simpler sugars. They are usually composed of 3 to 7 carbon atoms and have a general formula of (CH2O)n, where n is a number between 3 and 7. Examples of monosaccharides include glucose, fructose, and galactose.
When two monosaccharides are joined together by a glycosidic bond, they form a disaccharide. Disaccharides are composed of two simple sugars and can be broken down into their constituent monosaccharides by hydrolysis. Examples of disaccharides include sucrose, lactose, and maltose.
Option a) is incorrect because it describes the composition of a disaccharide, not a monosaccharide. Option
c) is incorrect because both monosaccharides and disaccharides can be found in both plants and animals.
Option d) is incorrect because both monosaccharides and disaccharides can be used for energy storage and
structural purposes, depending on their specific structure and function in the organism.
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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.
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