The Cell Quiz #3

The nucleus is the correct answer because it is the organelle that contains DNA. DNA is the genetic material that carries the instructions for the functioning and development of living organisms. The nucleus houses the DNA in the form of chromosomes, which are tightly coiled structures. The DNA within the nucleus controls the activities of the cell and is responsible for transmitting genetic information from one generation to the next. Other organelles, such as mitochondria, also contain DNA, but the majority of the cell's DNA is found in the nucleus.

Ribosomes are responsible for synthesizing proteins in a cell. They are small, spherical organelles found either freely floating in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the genetic information encoded in the mRNA and use it to assemble amino acids into a polypeptide chain, which eventually folds into a functional protein. Therefore, ribosomes play a crucial role in protein synthesis, making them the correct answer to the question.

Mitochondria are the cell organelles responsible for producing ATP, which is the main energy currency of the cell. Through a process called cellular respiration, mitochondria convert nutrients into ATP molecules, releasing energy that can be used for various cellular activities. The inner membrane of mitochondria contains enzymes and electron transport chains that are crucial for ATP synthesis. Therefore, mitochondria are commonly referred to as the "powerhouses" of the cell due to their role in energy production.

Photosynthesis occurs in the chloroplasts. Chloroplasts are the organelles found in plant cells that contain chlorophyll, which is responsible for capturing sunlight and converting it into energy through photosynthesis. This process is essential for plants to produce glucose and oxygen, which are crucial for their growth and survival. Therefore, the correct answer is chloroplasts.

The cell membrane is a selectively permeable barrier that controls the movement of substances in and out of the cell. It is composed of a phospholipid bilayer with embedded proteins that regulate the transport of molecules. This organelle plays a crucial role in maintaining homeostasis by allowing necessary nutrients and molecules to enter the cell while keeping harmful substances out. Additionally, it helps in communication between cells and provides structural support to the cell.

Lysosomes are cell organelles that contain enzymes responsible for breaking down waste materials in the cell. These enzymes, known as hydrolytic enzymes, help in the digestion of macromolecules such as proteins, lipids, carbohydrates, and nucleic acids. Lysosomes play a crucial role in maintaining cellular homeostasis by recycling cellular components and eliminating waste products. They also aid in the destruction of foreign substances, such as bacteria and viruses, that enter the cell.

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If the ribosomes of a cell were destroyed, the most likely effect on the cell would be that it would be unable to synthesize proteins. Ribosomes are responsible for protein synthesis in a cell, so their destruction would disrupt this process. Proteins are essential for various cellular functions, including structural support, enzymatic activity, and cell signaling. Without the ability to synthesize proteins, the cell would not be able to carry out these functions properly, leading to a variety of cellular dysfunction and potentially cell death.

The correct answer is (3) ribosome—synthesis of proteins. Ribosomes are responsible for protein synthesis, which is the process of creating proteins from amino acids. 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 genetic information in mRNA and use it to assemble amino acids into a polypeptide chain, which then folds into a functional protein.

Mitochondria are the organelles responsible for providing energy to cells through the process of cellular respiration. They generate ATP, which is the main energy currency of the cell. Since sperm cells are constantly moving and require a high amount of energy for their activity, it makes sense that mitochondria, which produce energy, would be the organelles most directly responsible for providing this energy.

Structure A is responsible for creating ATP. ATP, or adenosine triphosphate, is the main source of energy for cellular processes. Therefore, the function of structure A is to generate ATP, which is essential for the cell's energy needs.

The biologist would most likely infer that fat tissue requires less energy than thyroid tissue because the statement mentions that fat cells have fewer mitochondria than thyroid cells. Mitochondria are responsible for producing energy in cells, so fewer mitochondria in fat cells suggest that they require less energy compared to thyroid cells.

Homeostasis in unicellular organisms depends on the proper functioning of organelles. Organelles are specialized structures within a cell that perform specific functions necessary for maintaining the internal environment of the cell. They help regulate processes such as nutrient uptake, waste removal, and energy production, which are essential for the survival and stability of the cell. Without the proper functioning of organelles, the cell would not be able to maintain a stable internal environment, leading to disruptions in homeostasis. Insulin, antibodies, and guard cells do not play a direct role in homeostasis in unicellular organisms.

Chloroplasts are only found in plant cells and are responsible for photosynthesis, converting sunlight into energy. The cell wall is a rigid structure that provides support and protection to plant cells. The central vacuole is a large fluid-filled organelle that stores water, nutrients, and waste products in plant cells. The nucleus, cell membrane, and mitochondria are found in both plant and animal cells.