1. Diffusion
Flashcards
- Define diffusion.
- The net movement of particles from a region of higher concentration to a region of lower concentration due to random movement.
- Does diffusion require energy?
- No, it is a passive process.
- What is a concentration gradient?
- The difference in concentration between two regions.
- Name four factors that increase the efficiency of diffusion.
- Short distance, large concentration gradient, large surface area, and high temperature.
Multiple-choice questions
- What is the primary driver of diffusion?
- a) Active transport
- b) Random movement of particles
- c) Energy from mitochondria
- d) External pressure on the cell
Answer: b) Random movement of particles. Diffusion occurs as a direct result of the random movement of particles, which leads to a net movement from high to low concentration.
- Which of the following conditions makes diffusion most efficient?
- a) Longer distance
- b) Lower temperature
- c) Larger surface area
- d) Smaller concentration gradient
Answer: c) Larger surface area. Diffusion is more efficient when there is a larger surface area available, as it allows more particles to pass through simultaneously.
- How does temperature affect the rate of diffusion?
- a) Higher temperature increases kinetic energy
- b) Higher temperature decreases kinetic energy
- c) Temperature has no effect on diffusion
- d) Lower temperature increases particle movement
Answer: a) Higher temperature increases kinetic energy. At higher temperatures, molecules possess more kinetic energy, which causes them to move faster and increases the rate of diffusion.
2. Osmosis
Flashcards
- Define osmosis.
- The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
- What type of membrane is required for osmosis?
- A partially permeable membrane.
- What happens to animal cells in pure water?
- They burst because they lack a cell wall.
- Why don't plant cells burst in water?
- They have a tough, inelastic cell wall that provides structural support.
Multiple-choice questions
- What is the primary definition of osmosis?
- a) Movement of solutes from low to high concentration
- b) Movement of water from high to low water potential
- c) Movement of ions through a fully permeable membrane
- d) Energy-dependent movement of water molecules
Answer: b) Movement of water from high to low water potential. Osmosis is specifically defined as the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
- Why do plant cells not burst when placed in pure water?
- a) They have a mechanism to pump water out
- b) They have a tough, inelastic cell wall
- c) They do not take in water via osmosis
- d) They have a low internal water potential
Answer: b) They have a tough, inelastic cell wall. Plant cells are supported by the pressure of water inside the cell pushing against the tough cell wall, which prevents the cell from bursting even when it becomes swollen.
- In animals, what is the role of plasma in transport?
- a) It acts as a solid barrier for toxic waste
- b) It is a water-based liquid that dissolves substances
- c) It prevents water from entering the cells
- d) It provides energy for active transport
Answer: b) It is a water-based liquid that dissolves substances. Plasma is a water-based liquid that serves as a transport medium for dissolving and carrying substances like carbon dioxide, glucose, and hormones throughout the body.
3. Active Transport
Flashcards
- Define active transport.
- The movement of particles through a cell membrane against their concentration gradient using energy from respiration.
- What is the primary difference between diffusion and active transport?
- Diffusion is passive and moves down a gradient, while active transport requires energy and moves against a gradient.
- What process provides the energy for active transport?
- Respiration.
- Which organelle controls energy release?
- Mitochondria.
Multiple-choice questions
- What is the primary source of energy for active transport?
- a) Photosynthesis
- b) Respiration
- c) Diffusion
- d) Osmosis
Answer: b) Respiration. Active transport requires energy to move substances against a concentration gradient, and this energy is specifically supplied through the process of respiration.
- Which cell organelle is responsible for controlling energy release for active transport?
- a) Nucleus
- b) Ribosome
- c) Mitochondria
- d) Cell wall
Answer: c) Mitochondria. Mitochondria are the organelles in the cytoplasm that control energy release, which is necessary to fuel active transport processes.
- What type of molecules are responsible for moving particles across the membrane in active transport?
- a) Carrier proteins
- b) Lipid bilayers
- c) Water channels
- d) Sugar molecules
Answer: a) Carrier proteins. Carrier proteins located within the cell membrane play a crucial role by using energy to transport particles across the membrane against the concentration gradient.
And 18 more flashcards and 12 more questions in the document.
Document text
BIOLOGY MOVEMENT IN AND OUT OF CELLS CAMILA MENDOZA The net movement of particles from a region of their higher concentration to a region of lower concentration (i.e. down a concentration gradient), as a result of their random movement. Is a really important process for living organisms because it helps to provide essential gases and solutes (materials in solution), and also helps to remove some substances that are potentially toxic (poisonous). These move into or out of the cell through the cell membrane. Diffusion The factors that help diffusion to be efficient are: *distance (the shorter the better), for example the thin walls of alveoli and capillaries.
*concentration gradient (the bigger the better); this can be maintained by removing the substance as it passes across the diffusion surface (think about oxygenated blood being carried away from the surface of alveoli). *surface area for diffusion (the larger the better), for example there are millions of alveoli in a lung, giving a huge surface area for the diffusion of oxygen. *temperature (molecules have more kinetic energy at higher temperatures). Diffusion The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane. Is a special form of diffusion.
It always involves the movement of water across a partially permeable membrane. Plants rely on osmosis to obtain water through their roots. They use water as a transport medium to carry dissolved mineral ions, sucrose and aminoacids around the plant through the xylem and phloem vessels, and to maintain the firmness of cells. When young plants lose more water than they gain, cells become limp and the plants wilt. Osmosis Water is important to living things as a solvent – many substances (solutes) dissolve in it. Examples include glucose, mineral ions and aminoacids.
In animals, water is essential for the following processes: *Digestion – water helps to break down and dissolve food molecules in the process of digestion. *Transport – blood is made up of cells and a water-based liquid called plasma. The plasma is a way of transporting many dissolved substances, for example carbon dioxide, urea, glucose and hormones. *Excretion – water is important in the process of excretion in animals because some of the excretory materials, for example urea, are toxic. Water dilutes these to make them less poisonous. Urine is a solution containing dissolved mineral ions, urea, used hormones and drugs.
Osmosis Effects of osmosis on plant and animal tissues: When placed in water, plant and animal cells will take in the water through their cell membranes by diffusion. The diffusion of water in this way is called osmosis. Plant cells become swollen, but do not burst because of their tough cell wall. Plants are supported by the pressure of water inside the cells pressing outwards on the cell wall, which is inelastic and prevents further net entry of water. Animal cells will burst because they have no cell wall. The reverse happens when plant and animal cells are placed in concentrated sugar or salt solutions – plant and animal cells become limp.
Remember that sugars and mineral ions do not move by osmosis. Cell membranes can prevent some substances entering or leaving the cell. Osmosis The movement of particles through a cell membrane from a region of their lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration. Note the two big differences between diffusion and active transport: *The direction of movement (down a gradient, or up a gradient). *Whether or not energy is needed for the movement. Active transport Animals and plants rely on active transport to move some substances because the concentration gradient is not always the right way round for diffusion.
However, cells need to provide energy to achieve movement by active transport. This energy is supplied through respiration. Mitochondria (cell organelles in the cytoplasm) control energy release. Respiratory poisons block energy release, so they can prevent active transport. Protein molecules, called carriers, in the cell membrane play an important part in moving particles across the membrane. The protein uses energy to move the particles against their concentration gradient. Active transport