are functional units of the spleen.

are functional units of the pancreas.

Free BSGS Natural Sciences Question and Answer — Questions and Answers

Question 1: During the mitotic prophase,

tetrads of chromatids appear.
the centriole reappears.
chromosomes are doubled and the duplicate chromotids may be observed. (Correct answer)
During the mitotic prophase,

Correct answer: chromosomes are doubled and the duplicate chromotids may be observed.

During the mitotic prophase, the cell's chromatin condenses into visible chromosomes. Each chromosome has already replicated during the S phase, so it consists of two identical sister chromatids joined at the centromere. Therefore, "chromosomes are doubled and the duplicate chromatids may be observed" accurately describes a key event of this stage.

Question 2: Nephrons

are functional units of the spleen.
regulate body temperature
excrete only water.
filter the blood and reabsorb useful substances. (Correct answer)
are functional units of the pancreas.

Correct answer: filter the blood and reabsorb useful substances.

Nephrons are the microscopic functional units of the kidney, responsible for filtering blood and forming urine. They play a crucial role in maintaining fluid and electrolyte balance, removing waste products, and reabsorbing essential substances like glucose, amino acids, and water back into the bloodstream. This process ensures the body retains useful substances while excreting waste.

Question 3: Lake eutrophication is a risk.

when there is insufficient phosphorus
when essential nutrients are insufficient.
when there is excess phosphorus. (Correct answer)
during prolonged high temperatures.
as a result of too many fish.

Correct answer: when there is excess phosphorus.

Lake eutrophication is primarily caused by an excessive input of nutrients, particularly phosphorus and nitrogen, into aquatic ecosystems. When there is "excess phosphorus," it acts as a limiting nutrient, stimulating rapid growth of algae and aquatic plants. This overgrowth eventually leads to oxygen depletion when the plants die and decompose, harming other aquatic life.

Question 4: The cause of etiolation in plants is:

insufficient light. (Correct answer)
synergism.
photoperiodism.
parthenocarpy.
taxis.

Correct answer: insufficient light.

Etiolation is a plant growth response that occurs in the absence of light. Plants undergoing etiolation exhibit characteristics such as elongated, weak stems, pale yellow leaves (due to lack of chlorophyll), and reduced leaf development. This adaptation allows the plant to quickly grow towards a light source, making "insufficient light" the direct cause.

Question 5: When one population is dependent on the advantages provided by another population in order to live, the connection is known as:

mutualism (Correct answer)
aggregation
communalism
coordination
neutralism

Correct answer: mutualism

Mutualism is a type of symbiotic relationship where two different species interact in a way that is beneficial to both. In this scenario, if one population is dependent on the advantages provided by another population to live, and presumably the other population also benefits (or at least isn't harmed), it describes a mutualistic interaction where both parties gain from the association.

Question 6: How does niacin help to maintain?

normal nerve functioning (Correct answer)
normal blood clotting
normal bone formation
normal cellular oxidations
night vision

Correct answer: normal nerve functioning

Niacin, also known as Vitamin B3, is a crucial B vitamin that plays a vital role in numerous metabolic processes, including energy production. It is also essential for maintaining the health of the nervous system, digestive system, and skin. Therefore, "normal nerve functioning" is a key benefit of adequate niacin intake.

Question 7: In an ecosystem, sulfur is significant because it is:

important for salt balance in vertebrate blood.
important in nerve impulse transmission
essential in photosynthesis.
essential for many proteins in certain enzymes. (Correct answer)

Correct answer: essential for many proteins in certain enzymes.

Sulfur is an essential macronutrient for all living organisms. It is a critical component of two amino acids, methionine and cysteine, which are fundamental building blocks of proteins. Consequently, sulfur is vital for the structure and function of many proteins and enzymes, making it indispensable for various biological processes in an ecosystem.

Question 8: Although they have the same elements as carbohydrates—carbon, hydrogen, and oxygen—fats are different from them in that they:

little stored energy
proportionally less oxygen (Correct answer)
twice as much hydrogen as oxygen
proportionally more oxygen
an excess of carbon

Correct answer: proportionally less oxygen

While both fats and carbohydrates are composed of carbon, hydrogen, and oxygen, their proportions differ significantly. Fats (lipids) have a much lower proportion of oxygen atoms compared to hydrogen and carbon atoms than carbohydrates do. This difference in elemental composition is why fats are more energy-dense and less oxidized than carbohydrates.

Question 9: Folic acid deficiency could lead to:

a type of anemia (Correct answer)
beriberi
hemorrhage following surgery
sterility
gray hair

Correct answer: a type of anemia

Folic acid (Vitamin B9) is essential for the production of red blood cells and DNA synthesis. A deficiency impairs the bone marrow's ability to produce healthy red blood cells, leading to megaloblastic anemia. This condition is characterized by abnormally large, immature red blood cells, reducing the blood's oxygen-carrying capacity.

Question 10: An organism that can create its own nourishment is referred to as:

parasitic
holozoic
saprophytic
autotrophic (Correct answer)
heterotrophic

Correct answer: autotrophic

Autotrophic organisms are capable of producing their own food from inorganic substances, typically through photosynthesis or chemosynthesis. This ability to create their own nourishment, often using light or chemical energy, places them at the base of most food chains as producers. Examples include plants, algae, and some bacteria.

Question 11: An egg and sperm joining together is known as:

germination.
meiosis.
fertilization. (Correct answer)
homospory.
reduction.

Correct answer: fertilization.

Fertilization is the biological process where a male gamete (sperm) fuses with a female gamete (egg) to form a zygote. This union combines genetic material from both parents, initiating the development of a new organism. It is a fundamental step in sexual reproduction across many species.

Question 12: Water is lost by transpiration as a result of

adhesive forces
cohesive forces
capillarity
mass movement
diffusion (Correct answer)

Correct answer: diffusion

Transpiration is the process of water movement through a plant and its evaporation from aerial parts, primarily leaves. Water vapor diffuses from the moist air spaces inside the leaf to the drier air outside through stomata. This movement is driven by the water potential gradient, which is a form of diffusion.

Question 13: Where in the chloroplast do the "dark" processes of photosynthesis occur?

carotene.
stroma. (Correct answer)
chlorophyll.
grana.
stomata.

Correct answer: stroma.

The "dark" processes of photosynthesis, also known as the Calvin cycle, occur in the stroma of the chloroplast. During this cycle, ATP and NADPH produced during the light-dependent reactions are used to fix carbon dioxide from the atmosphere. This process ultimately synthesizes glucose and other organic molecules.

Question 14: Fibrinogen is:

a reservior of antibodies
involved with blood clotting
a precursor of certain hormones.
a source of globulin.
converted to fibrin during clotting. (Correct answer)

Correct answer: converted to fibrin during clotting.

Fibrinogen is a soluble plasma protein that plays a crucial role in blood clotting. When an injury occurs, an enzyme called thrombin converts fibrinogen into insoluble fibrin monomers. These fibrin monomers then polymerize to form a mesh-like network, which traps blood cells and forms a stable clot to stop bleeding.

Question 15: You might anticipate seeing moose and spruce in the:

alpine tundra.
deciduous forest.
tropical rain forest.
grasslands.
coniferous forest. (Correct answer)

Correct answer: coniferous forest.

Coniferous forests, also known as taiga or boreal forests, are characterized by cold, long winters and short, mild summers. These conditions are ideal for coniferous trees like spruce, fir, and pine. Animals such as moose, deer, and bears are well-adapted to this biome, feeding on the vegetation and thriving in its climate.

Question 16: The likelihood of developing gametes with dominant genes ("AB") in a person with genotype AaBb is

1/8
1/16
1/2
1/4 (Correct answer)
None of the above.

Correct answer: 1/4

A person with genotype AaBb is heterozygous for two genes. During meiosis, alleles for each gene segregate independently. The probability of a gamete receiving 'A' is 1/2, and the probability of receiving 'B' is 1/2. Therefore, the likelihood of developing a gamete with both dominant genes ('AB') is the product of these independent probabilities: (1/2) * (1/2) = 1/4.

Free BSGS Natural Sciences Question and Answer

During the mitotic prophase,