7th Grade Life Science Quiz

Exocytosis is the correct answer because it is a process by which large particles are actively transported out of a cell. During exocytosis, vesicles containing the particles fuse with the cell membrane, releasing the contents outside the cell. This process is important for the secretion of molecules such as hormones, neurotransmitters, and digestive enzymes. In contrast, endocytosis is the process by which particles are taken into the cell, so it is not the correct answer in this context.

In order for a cell to transport particles by active transport, it requires energy. Active transport is a process that moves particles against their concentration gradient, from an area of lower concentration to an area of higher concentration. This process requires the cell to expend energy to pump the particles across the cell membrane. Without energy, the cell would not be able to carry out active transport and transport particles against their concentration gradient.

Passive transport refers to the movement of molecules across a cell membrane without the use of energy. Diffusion is a passive transport process where molecules move from an area of higher concentration to an area of lower concentration. Osmosis is another example of passive transport, specifically the diffusion of water molecules through a selectively permeable membrane, from an area of lower solute concentration to an area of higher solute concentration. Both diffusion and osmosis occur naturally and do not require the cell to expend energy.

Osmosis is the correct answer because it refers to the diffusion of water through a semipermeable membrane. In osmosis, 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 process is important for maintaining the balance of water and solutes in living organisms.

Water is made up of particles called molecules. Molecules are the smallest unit of a substance that retains its chemical properties. In the case of water, each water molecule is made up of two hydrogen atoms bonded to one oxygen atom. These molecules are constantly moving and interacting with each other, giving water its unique properties such as its ability to dissolve many substances and its high heat capacity. Therefore, the correct answer is molecules.

During the process of exocytosis, an ell (presumably meant to be "cell") forms vesicles that are sacs made from pieces of the cell membrane. These vesicles carry particles to the cell membrane. Subsequently, the vesicle fuses with the cell membrane, allowing the particles to be released outside of the cell.

The movement of materials across the cell membrane is crucial for an organism's survival because it controls what substances enter and exit the cell. This regulation ensures that essential nutrients and molecules necessary for cellular processes can enter the cell, while waste products and harmful substances can be expelled. Without this control, the cell would not be able to maintain homeostasis and carry out its functions effectively.

Osmosis is the process by which water molecules move from an area of lower solute concentration to an area of higher solute concentration through a selectively permeable membrane. In this case, water travels into cells because their cells are mostly water. This movement of water helps to maintain the balance of solutes inside and outside the cells. It is important for various cellular processes and ensures that cells do not shrivel up or become dehydrated.

When red blood cells are placed in a salty solution, the concentration of solutes outside the cells becomes higher than inside the cells. This creates a hypertonic environment, causing water to move out of the cells through osmosis. As a result, the red blood cells lose water and shrink in size, a process known as cell shrinkage or cell shrinkage. Therefore, the correct answer is that the red blood cells shrivel up.

Endocytosis is the correct answer because it is a process by which large particles can enter a cell. During endocytosis, the cell membrane surrounds the particle and forms a vesicle, which then brings the particle into the cell. This process requires energy and is considered a form of active transport. Exocytosis, on the other hand, is the process by which particles are released from the cell, not brought into it. Therefore, endocytosis is the correct active transport process for the entry of large particles into a cell.

Diffusion is the movement of particles from areas of high concentration to areas of low concentration. This process occurs due to the random motion of particles, where they spread out to achieve a state of equilibrium. It is a fundamental process in nature that allows substances to move and mix, such as the spreading of a scent in a room or the movement of oxygen into our cells during respiration. Diffusion does not require a membrane or any specific medium, unlike osmosis which specifically refers to the movement of water molecules across a semi-permeable membrane.

When a wilted plant is watered, the water travels into the plant's cells. This helps to replenish the lost water and nutrients, causing the plant to rehydrate. As a result, the plant's cells become turgid and regain their normal shape, causing the plant to "fern up" and regain its original healthy appearance.

Channels are passageways in a cell membrane that allow the transport of specific molecules or ions across the membrane. Unlike active transport, which requires energy, channels facilitate passive transport, specifically diffusion and osmosis. Channels provide a selective pathway for the movement of substances, allowing them to cross the cell membrane more easily. Therefore, channels are the correct answer in this context.

The fluids that surround and fill a cell are mostly made of water. Water is essential for cellular processes and provides a medium for molecules to move and interact within the cell. It helps to maintain the cell's shape, transport nutrients and waste products, and regulate temperature. Without water, cells would not be able to function properly and maintain homeostasis.

The nucleus is the correct answer because it controls all cell activity and is found in both animal and plant cells. It contains the cell's DNA and is responsible for regulating gene expression and directing cell division. The nucleus acts as the control center of the cell, coordinating all cellular processes and maintaining the cell's overall function and structure.

Passive transport refers to the movement of particles across a cell membrane without requiring energy. This process occurs through channels that allow the particles to passively diffuse from an area of higher concentration to an area of lower concentration. Unlike active transport, which requires energy, passive transport relies on the natural concentration gradient of the particles. Diffusion and osmosis are specific types of passive transport where particles move from an area of higher concentration to an area of lower concentration and the movement of water across a membrane, respectively.

Mitochondria are the main power source in a cell and are found in both plant and animal cells. They are responsible for producing energy in the form of ATP through cellular respiration. Mitochondria have their own DNA and are believed to have originated from ancient bacteria that formed a symbiotic relationship with early eukaryotic cells. They have a double membrane structure and contain enzymes that are essential for the production of ATP. Therefore, mitochondria are the correct answer as they play a crucial role in energy production within cells.

The channels in a cell membrane are made up of proteins. Proteins are large molecules that play a crucial role in many biological processes. In the context of cell membranes, proteins form channels or pores that allow the passage of specific molecules or ions in and out of the cell. These channels are important for various cellular functions such as nutrient uptake, waste removal, and cell signaling. Therefore, the answer is proteins.

The cell membrane is a protective barrier that encloses a cell and is found in both plant and animal cells. It regulates the movement of substances in and out of the cell, allowing nutrients to enter and waste products to exit. It also provides structural support and helps maintain the shape of the cell. The cell membrane is composed of a phospholipid bilayer with embedded proteins that control the transport of molecules and ions. Therefore, the cell membrane is the correct answer for this question.

Ribosomes are responsible for protein synthesis in both plant and animal cells. They can be found in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the genetic information from the nucleus and use it to assemble amino acids into proteins. Therefore, ribosomes play a crucial role in the production of proteins, which are essential for various cellular functions and processes.

Osmosis is important to cell functions because cells are mostly composed of water. Osmosis is the process by which water molecules move from an area of lower concentration to an area of higher concentration, across a semi-permeable membrane. This movement of water is essential for maintaining the proper balance of water and solutes inside and outside of cells. It allows cells to regulate their internal environment, maintain their shape and size, and transport nutrients and waste products. Without osmosis, cells would not be able to function properly and may shrivel up or become damaged.

During the process of endocytosis, vesicles form sacs from pieces of the cell membrane. This means that the cell membrane invaginates or folds inward, forming a vesicle that encloses the extracellular material or particles. This allows the cell to engulf and internalize substances from the external environment. The vesicle then carries these particles to the cell membrane, fuses with it, and releases the particles outside of the cell. This process is important for nutrient uptake, removal of waste, and regulation of cell signaling.

Active transport is the correct answer because it involves the movement of particles from an area of low concentration to an area of high concentration across a cell membrane. This process requires the use of energy to transport molecules or ions against their concentration gradient. Active transport is carried out by specific proteins called pumps, which use ATP hydrolysis to move molecules across the membrane. This process is crucial for maintaining proper ion concentrations and for the uptake of nutrients in cells.

Photosynthesis, the process by which plants convert sunlight into energy, primarily occurs in the chloroplasts of leaves. While other parts of the plant have important functions, the leaves are the primary site for photosynthesis.