Keystone Biology Exam 2025. Actual Exam Questions and Correct Answers. Genuine Summer/Fall Update.

Keystone Biology Exam 2025. Actual Exam Questions and Correct Answers. Genuine 2025- 2026 Summer/Fall Update. Which statement best describes a difference between prokaryotic cells and eukaryotic cells? - CORRECT ANS The presence of membrane-bound organelles in eukaryotic cells indicates that they are more complex than prokaryotic cells. Which characteristic is shared by all prokaryotes and eukaryotes? - CORRECT ANS ability to store hereditary information 1.2.1Living organisms can be classified as prokaryotes or eukaryotes. Which two structures are common to both prokaryotic and eukaryotic cells? - CORRECT ANS plasma membrane and cytoplasm Which statement best describes an effect of the low density of frozen water in a lake? - CORRECT ANS When water in a lake freezes, it floats, providing insulation for organisms below. Which statement correctly describes how carbon's ability to form four bonds makes it uniquely suited to form macromolecules? - CORRECT ANS It forms large, complex, diverse molecules. Carbohydrates and proteins are two types of macromolecules. Which functional characteristic of proteins distinguishes them from carbohydrates? - CORRECT ANS ability to catalyze biochemical reactions Substance A is converted to substance B in a metabolic reaction. Which statement best describes the role of an enzyme during this reaction? - CORRECT ANS It speeds up the reaction without being consumed. A scientist observes that, when the pH of the environment surrounding an enzyme is changed, the rate the enzyme catalyzes a reaction greatly decreases. Which statement best describes how a change in pH can affect an enzyme? - CORRECT ANS A pH change can cause the enzyme to change its shape. Using a microscope, a student observes a small, green organelle in a plant cell. Which energy transformation most likely occurs first within the observed organelle? - CORRECT ANS light to chemical Photosynthesis and cellular respiration are two major processes of carbon cycling in living organisms. Which statement correctly describes one similarity between photosynthesis and cellular respiration? - CORRECT ANS Both include reactions that transform energy. A protein in a cell membrane changed its shape to move sodium and potassium ions against their concentration gradients. Which molecule was most likely used by the protein as an energy source? - CORRECT ANS ATP A sodium-potassium pump within a cell membrane requires energy to move sodium and potassium ions into or out of a cell. The movement of glucose into or out of a cell does not require energy. Which statement best describes the movement of these materials across a cell membrane? - CORRECT ANS Sodium and potassium ions move by active transport, and glucose moves by facilitated diffusion. The rough endoplasmic reticulum and Golgi apparatus work together in eukaryotic cells. What is one way that the rough endoplasmic reticulum assists the Golgi apparatus? - CORRECT ANS It packages new protein molecules into vesicles. Which example is an activity that a fish most likely uses to maintain homeostasis within its body? - CORRECT ANS exchanging gases through its gills to regulate oxygen levels Mitosis and meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis? - CORRECT ANS Mitosis produces genetically identical daughter cells Which process helps to preserve the genetic information stored in DNA during DNA replication? - CORRECT ANS nucleotides lining up along the template strand according to base pairing rules In a flowering plant species, red flower color is dominant over white flower color. What is the genotype of any red-flowering plant resulting from this species? - CORRECT ANS a red allele present on at least one of two homologous chromosomes Genotype ii is bloodtype O, IAIA, IAi is A, IBIB, IBi is B, and IAIB is AB. Blood type is inherited through multiple alleles, including IA, IB, and i. A child has type A blood. If the father has type AB blood, what are all the possible phenotypes of the mother? - CORRECT ANS phenotypes O, A, B, AB Which statement describes a cell process that is common to both eukaryotic and prokaryotic cells? - CORRECT ANS Both cell types use ribosomes to carry out translation. The endoplasmic reticulum is a network of membranes within the cell, and it is often classified as rough or smooth, depending on whether there are ribosomes on its surface. Which statement best describes the role of rough endoplasmic reticulum in the cell? - CORRECT ANS It aids in the production of membrane and secretory proteins. A genetic mutation resulted in a change in the sequence of amino acids of a protein, but the function of the protein was not changed. Which statement best describes the genetic mutation? - CORRECT ANS It was a silent mutation that caused a change in the DNA of the organism.