The nucleus stores the cell's genetic material and regulates its activities, making it the control center. Other organelles have specialized functions such as energy production or protein synthesis.

The cell membrane regulates the passage of materials in and out of the cell through its semi-permeable structure. It does not generate energy, synthesize proteins, or store genetic material.

Plant cells have a cell wall that provides extra support and protection, which is absent in animal cells. Animal cells rely solely on the cell membrane for their outer boundary.

Photosynthesis occurs in the chloroplasts where chlorophyll absorbs light energy. Other organelles like the mitochondria and nucleus are responsible for different cellular functions.

A gene is a segment of DNA containing the instructions needed to build proteins, which in turn determine an organism's traits. The other options describe roles performed by proteins, organelles, or other molecules.

Oxygen functions as the final electron acceptor in the electron transport chain by combining with electrons and protons to form water. This step is essential for maintaining the flow of electrons and efficient ATP production.

Prokaryotic cells do not possess a nucleus or other membrane-bound organelles, which are key features of eukaryotic cells. This difference is fundamental to understanding the complexity and functionality of each cell type.

Mendel's experiments with pea plants showed that traits are inherited as discrete units, which we now refer to as genes. His findings laid the groundwork for modern genetics by introducing the concepts of dominant and recessive traits.

DNA polymerase is the enzyme that synthesizes a new strand of DNA by adding nucleotides complementary to the template strand. The other enzymes play roles in unwinding the DNA or joining fragments together.

A mutation is a permanent change in the DNA sequence, which can affect protein function and lead to variation in traits. These changes may be beneficial, harmful, or neutral depending on the context.

Enzyme activity typically increases with temperature until reaching an optimum level. Beyond this point, excessive heat can lead to enzyme denaturation, resulting in a loss of function.

The smooth endoplasmic reticulum functions in lipid synthesis and detoxification processes. In contrast, the rough endoplasmic reticulum is primarily involved in protein synthesis due to the presence of ribosomes on its surface.

Producers, such as plants, generate food through photosynthesis, whereas consumers depend on other organisms for energy. This fundamental difference is key to understanding energy flow in an ecosystem.

The vascular system, composed of xylem and phloem, is responsible for transporting water, minerals, and the products of photosynthesis throughout the plant. This system is crucial for maintaining plant structure and function.

Metaphase is the stage of mitosis where chromosomes line up along the cell's equatorial plane, ensuring that each daughter cell receives an equal set of chromosomes. This alignment is critical for accurate chromosome segregation.

Telomerase adds nucleotide sequences to the ends of chromosomes to prevent telomere shortening during cell division. While this maintains chromosomal integrity and delays aging, its overactivity can result in unchecked cell division, a characteristic of cancer.

Crossing over in prophase I of meiosis allows homologous chromosomes to exchange genetic material, thereby creating new combinations of alleles. This process is crucial for increasing genetic diversity, which is fundamental for evolution and adaptation.

Genetic drift causes random fluctuations in allele frequencies, especially in small populations, without regard to the advantage of traits. In contrast, natural selection systematically favors alleles that confer survival and reproductive benefits.

The tertiary structure defines the overall three-dimensional shape of a protein, which directly impacts its functionality by determining the configuration of its active sites. Proper folding is essential for biological activity, and misfolding can lead to loss of function or disease.

A keystone species plays a critical role in maintaining the structure and balance of its ecosystem despite not necessarily being the most abundant. Its influence helps regulate populations and maintain biodiversity, so its removal can lead to significant ecological shifts.