Benchmark Assessment #2: Biochemistry & The Cell

Prophase (chromosomes condense & nuclear membrane disappears)
Metaphase (chromosomes line up in the MIDDLE)
Anaphase (chromosomes are pulled APART)
Telophase (2 nuclear membranes form & cytokinesis occurs

Urine has the greatest concentration of hydroxide ions (OH-) because it has a higher pH value of 6.0 compared to the other solutions. pH is a measure of the concentration of hydrogen ions (H+) in a solution, and a higher pH indicates a lower concentration of H+ ions. Since hydroxide ions (OH-) and hydrogen ions (H+) are inversely related, a higher pH means a higher concentration of hydroxide ions. Therefore, urine with a pH of 6.0 has the greatest concentration of hydroxide ions among the given solutions.

The Golgi apparatus is responsible for processing and packaging cellular materials before they are exported. It contains smooth-sided channels called cisternae, which are involved in modifying and sorting proteins and lipids. This organelle does not play a role in digestion, detoxification, or energy harvesting, making the processing and packaging of cellular materials the most appropriate activity for identifying it as the Golgi apparatus.

Enzymes speed up chemical reactions by reducing activation energy. Activation energy is the energy required to start a reaction, and enzymes lower this energy barrier, allowing the reaction to occur more easily and quickly. Enzymes achieve this by binding to reactant molecules and bringing them closer together, facilitating the formation of new bonds and increasing the likelihood of a successful reaction. By reducing the activation energy, enzymes increase the rate of the reaction without being consumed in the process.

The key factor that distinguishes organic compounds from inorganic compounds is the presence of carbon. Organic compounds are defined as compounds that contain carbon, while inorganic compounds do not necessarily contain carbon. Carbon is unique in its ability to form covalent bonds with other elements, allowing for the formation of complex and diverse organic molecules. This characteristic of carbon is what gives organic compounds their distinct properties and enables them to play crucial roles in biological processes.

The electron transport chain generates most of the ATP produced during cellular respiration. This process occurs in the inner mitochondrial membrane and involves the transfer of electrons from electron donors to electron acceptors, creating a proton gradient. This gradient is then used by ATP synthase to produce ATP through oxidative phosphorylation. The electron transport chain is the final stage of cellular respiration and is responsible for the majority of ATP production in aerobic organisms.

Amino acids contain an amino group (-NH2) in their structure, which is absent in monosaccharides, polysaccharides, fatty acids, and glycerol. The presence of the amino group is what distinguishes amino acids from other molecules mentioned.

Papain is an enzyme found in papaya that belongs to the protease family. Proteases are enzymes that help break down proteins into smaller peptides or amino acids. Therefore, papain helps in the digestion of proteins. It does not help digest carbohydrates, fatty acids, or nucleic acids.

Cyclohexamide is an antibiotic that specifically inhibits protein synthesis. It works by binding to the ribosomes, the cellular organelles responsible for protein synthesis. By inhibiting the ribosomes, cyclohexamide prevents the completion of protein synthesis, resulting in the formation of short incomplete segments of proteins. Therefore, the correct answer is Ribosome.

The most likely explanation for the cell's gain in mass is that the solution is hypotonic to the cell. In a hypotonic solution, there is a lower concentration of solutes outside the cell compared to inside the cell. As a result, water moves into the cell through osmosis, causing it to swell and gain mass.

The molecules move into the cell through the channel protein. The channel protein acts as a passageway or a tunnel through the cell membrane, allowing specific molecules to pass from outside to inside the cell. This process is known as facilitated diffusion, where the molecules move down their concentration gradient, meaning from an area of higher concentration to an area of lower concentration. The phospholipid bilayer of the cell membrane also plays a role in maintaining the integrity and structure of the cell, but in this case, the molecules are specifically moving through the channel protein.

The presence of chloroplast indicates that cells are photosynthetic bacteria. Photosynthetic bacteria have the ability to convert sunlight into energy through the process of photosynthesis, which occurs in the chloroplasts. Therefore, if chloroplast is present, it suggests that the cells are photosynthetic bacteria.

Glucose is the correct answer because during muscle contraction, glucose is broken down through a process called glycolysis to produce ATP, which is the main source of energy for muscle contraction. This process releases energy that is used for the contraction and relaxation of muscle fibers. ATP is then used by the muscle cells to power the movement and contraction of muscles.

Yeast respiration involves the breakdown of glucose to produce energy in the form of ATP. This process, known as fermentation, also produces carbon dioxide as a byproduct. Therefore, if ethanol is detected in the yeast culture, it suggests that the yeast culture also contains carbon dioxide and ATP. Lactic acid and oxygen are not directly involved in yeast respiration.

When the pH of the stomach increases due to the use of antacids, the active site of pepsin, which is responsible for binding to and breaking down proteins, undergoes a conformational change. This change in shape of the active site makes it less effective in binding to proteins and carrying out the digestion process. As a result, the efficiency of protein digestion is reduced.

During aerobic cellular respiration, ATP molecules form in the mitochondrial matrix and inner mitochondrial membrane. The process of aerobic respiration occurs in the mitochondria, where the breakdown of glucose takes place. The majority of ATP synthesis occurs in the inner mitochondrial membrane through the electron transport chain and chemiosmosis. The mitochondrial matrix also plays a role in ATP production through the Krebs cycle, where the breakdown products of glucose are further metabolized to generate energy. Therefore, the correct answer is that ATP molecules form in the mitochondrial matrix and inner mitochondrial membrane only.

When the pH in a stomach increases from 2 to 4, it means that the stomach becomes less acidic. As pH is a measure of hydrogen ion concentration, a higher pH indicates a lower concentration of hydrogen ions. Since the pH increases by 2 units, the hydrogen ion concentration decreases by a factor of 100 (10^2).

In the absence of light, Chlorella cannot perform photosynthesis to convert CO2 into glucose and oxygen. Instead, it relies on cellular respiration to generate energy by breaking down glucose and releasing CO2 as a byproduct. This is why there is a negative uptake (release) of CO2 under dark conditions.

The aerobic and anaerobic pathways of cellular respiration require pyruvate and NADH. Pyruvate is the end product of glycolysis and serves as the starting point for both aerobic and anaerobic respiration. NADH is produced during glycolysis and is an important electron carrier that is used in later steps of cellular respiration to generate ATP. ATP is also required for cellular respiration, but it is not specifically mentioned as a product of glycolysis in this question. Therefore, the correct answer is pyruvate and NADH.