1.
What is the basic unit of structure and function in living things?
Correct Answer
D. Cell
Explanation
The cell is the basic unit of structure and function in living things. It is the smallest unit of life that can carry out all of the necessary functions for an organism to survive and reproduce. Cells are responsible for carrying out various processes such as metabolism, growth, and reproduction. They also contain all of the necessary genetic material in the form of DNA. Therefore, the cell is considered the fundamental building block of all living organisms.
2.
The molecule that forms the core of the cell membrane is called the:
Correct Answer
B. pHospHobilayer
Explanation
The correct answer is phosphobilayer because the molecule that forms the core of the cell membrane is a phospholipid bilayer. The cell membrane is composed of two layers of phospholipids, with the hydrophilic (water-loving) heads facing outward and the hydrophobic (water-fearing) tails facing inward. This arrangement creates a barrier that regulates the movement of substances in and out of the cell, making the phospholipid bilayer essential for maintaining the integrity and functionality of the cell membrane.
3.
The process by which substances pass through the cell membrane without expending energy is called:
Correct Answer
B. Passive transport
Explanation
Passive transport is the correct answer because it refers to the movement of substances across the cell membrane without the use of energy. Unlike active transport, which requires the use of energy, passive transport relies on the concentration gradient to drive the movement of molecules. This can occur through processes such as diffusion, osmosis, and facilitated diffusion. Endocytosis and phagocytosis, on the other hand, involve the engulfment of substances by the cell membrane and require energy, making them forms of active transport.
4.
The process by which substances move from regions of high concentration to regions of low concentration is called:
Correct Answer
B. Diffusion
Explanation
Diffusion is the process by which substances move from regions of high concentration to regions of low concentration. This movement occurs due to the random motion of particles, which causes them to spread out and distribute evenly. Unlike active transport, diffusion does not require energy input from the cell. Phagocytosis and endocytosis involve the engulfment of particles or molecules by a cell, which is not the case in diffusion. Therefore, diffusion is the correct answer for the given question.
5.
The movement of water through a selectively peremeable membrane is known as:
Correct Answer
B. Osmosis
Explanation
Osmosis is the movement of water through a selectively permeable membrane. In this process, water molecules move from an area of lower solute concentration to an area of higher solute concentration, in order to equalize the concentration on both sides of the membrane. This movement occurs passively, without the need for energy input. Facilitated diffusion involves the movement of molecules through a membrane with the help of specific transport proteins. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. Active transport requires the use of energy to move molecules against their concentration gradient.
6.
Why is the nucleus important?
Correct Answer
D. All of these
Explanation
The nucleus is important because it contains nearly all of a cell's DNA, which carries the genetic instructions for the cell's functioning. Additionally, it is the control center of the cell, regulating all cellular activities and coordinating the cell's functions. Furthermore, the nucleus is present in eukaryotes, which are organisms with complex cells. Therefore, all of these reasons make the nucleus important.
7.
The site where ribosomes are assembled is the:
Correct Answer
D. Nucleolus
Explanation
The nucleolus is the correct answer because it is the site where ribosomes are assembled. Ribosomes are essential cellular structures involved in protein synthesis. The nucleolus is a distinct region within the nucleus of a cell, where ribosomal RNA (rRNA) is transcribed and combined with proteins to form ribosomes. This process of ribosome assembly occurs in the nucleolus before the ribosomes are exported to the cytoplasm, where they carry out their functions in protein synthesis.
8.
The elminiation of a particle by a single-celled organism is known as:
Correct Answer
C. Exocytosis
Explanation
Exocytosis is the process by which a cell releases particles or substances from its cytoplasm to the external environment. It involves the fusion of vesicles containing the particles with the cell membrane, causing the release of the contents outside the cell. In the context of the given question, the elimination of a particle by a single-celled organism would involve the particle being expelled or released from the organism's cell through exocytosis.
9.
Because bacteria do not contain nuclei, they are known as:
Correct Answer
A. Prokaryotes
Explanation
Bacteria are known as prokaryotes because they do not have a nucleus. Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and other membrane-bound organelles. Instead, their genetic material is located in the cytoplasm. This is in contrast to eukaryotes, which have a nucleus and other membrane-bound organelles. Phagocytes and endocytes are not related to the classification of bacteria based on the presence or absence of a nucleus.
10.
Which structure would a cell that is active in protein synthesis contain?
Correct Answer
D. Ribosomes
Explanation
A cell that is active in protein synthesis would contain ribosomes. Ribosomes are the cellular structures responsible for protein synthesis. They are found in both prokaryotic and eukaryotic cells and can be free-floating in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the messenger RNA (mRNA) and use it as a template to assemble amino acids into a protein chain. Therefore, the presence of ribosomes in a cell indicates its involvement in protein synthesis.
11.
Which cell structure would be involved in digesting worn-out ribosomes?
Correct Answer
D. Lysosomes
Explanation
Lysosomes are organelles that contain enzymes capable of breaking down cellular waste and debris. They are involved in the process of cellular digestion and the recycling of cellular components. In this case, lysosomes would be responsible for digesting and recycling worn-out ribosomes, which are cellular structures involved in protein synthesis.
12.
Which structures would be found in a maple tree cell but not a human cell?
Correct Answer
B. Chloroplasts and cell walls
Explanation
Chloroplasts are the organelles responsible for photosynthesis, which occurs in plant cells but not in human cells. Cell walls are also unique to plant cells and provide structural support and protection. Therefore, both chloroplasts and cell walls would be found in a maple tree cell but not in a human cell.
13.
Where does the final processing of proteins occur?
Correct Answer
A. Golgi bodies
Explanation
The final processing of proteins occurs in the Golgi bodies. The Golgi bodies receive proteins from the endoplasmic reticulum and modify them by adding sugars, lipids, or other molecules. They also sort and package the proteins into vesicles for transportation to their final destinations within or outside the cell. The Golgi bodies play a crucial role in ensuring that proteins are properly processed and ready for their specific functions.
14.
What substance does lysosomes contain?
Correct Answer
C. Enzymes
Explanation
Lysosomes are membrane-bound organelles found in the cytoplasm of cells. They contain various enzymes that are responsible for breaking down waste materials, cellular debris, and foreign substances. These enzymes are highly acidic and function optimally in an acidic environment. Therefore, the correct answer is enzymes.
15.
Which plant organelle stores water?
Correct Answer
D. Vacuole
Explanation
The vacuole is a plant organelle that stores water. It is a membrane-bound sac that can occupy a large portion of the cell's volume. The vacuole plays a crucial role in maintaining the cell's turgidity and regulating osmotic balance. It stores water, ions, nutrients, and waste products. Additionally, the vacuole can also store pigments and toxic compounds to protect the plant from predators. Therefore, the vacuole is responsible for storing water in plant cells.
16.
Which cell organelle can you find all other cell organelles?
Correct Answer
B. Cytoplasm
Explanation
The cytoplasm is the correct answer because it is the fluid-filled region of the cell where all other cell organelles are suspended. It contains various organelles such as the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and ribosomes. These organelles perform different functions within the cell and are all located within the cytoplasm. Therefore, the cytoplasm can be considered as the place where all other cell organelles are found.
17.
In which cell organelles can you find DNA?
Correct Answer
B. Nucleus and mitochondria
Explanation
The correct answer is nucleus and mitochondria. DNA, which carries genetic information, is primarily found in the nucleus of a cell. The nucleus is often referred to as the "control center" of the cell because it contains the DNA that regulates cell activities. Mitochondria, on the other hand, also contain DNA. Mitochondrial DNA is responsible for producing proteins essential for the mitochondria's function in energy production.
18.
Which cell organell is known as the "powerhouse" of the cell?
Correct Answer
B. Mitochondria
Explanation
Mitochondria are known as the "powerhouse" of the cell because they are responsible for generating energy in the form of ATP through cellular respiration. They have their own DNA and can self-replicate, suggesting that they were once independent organisms that formed a symbiotic relationship with eukaryotic cells. Mitochondria have a highly folded inner membrane that increases their surface area, allowing for more ATP production. They play a vital role in various cellular processes, such as metabolism, signaling, and cell death.
19.
Which cell organelle has the job of determining which substances can go into and out of the cell?
Correct Answer
A. Cell membrane
Explanation
The cell membrane is responsible for determining which substances can enter and exit the cell. It acts as a selectively permeable barrier, allowing certain molecules to pass through while blocking others. This process is essential for maintaining the cell's internal environment and regulating the movement of nutrients, waste products, and signaling molecules. The other organelles listed (ribosomes, endoplasmic reticulum, and lysosomes) have different functions and are not directly involved in controlling the movement of substances in and out of the cell.
20.
Which cell organelle acts as the "travel system" for the cell, allowing substances to move throughout the cell from one organelle to another?
Correct Answer
B. Endoplasmic reticulum
Explanation
The endoplasmic reticulum acts as the "travel system" for the cell, allowing substances to move throughout the cell from one organelle to another. It is a network of membranes that extends from the nuclear envelope throughout the cytoplasm. It is involved in the synthesis, modification, and transport of proteins and lipids within the cell. The rough endoplasmic reticulum, which is studded with ribosomes, is responsible for protein synthesis, while the smooth endoplasmic reticulum is involved in lipid metabolism and detoxification of drugs. Thus, the endoplasmic reticulum plays a crucial role in maintaining the internal organization and function of the cell.