Movement Of Substances Flashcards
Define diffusion
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient.
Diffusion plays a crucial role in nutrient uptake and gas exchange in both plants and humans.
What is the role of diffusion in nutrient uptake and gas exchange?
Diffusion facilitates the movement of nutrients and gases across membranes, ensuring that cells receive necessary substances and eliminate waste.
In plants, this process occurs in roots and leaves, while in humans, it occurs in the lungs and cells.
How does an increase in surface area-to-volume ratio affect diffusion?
An increase in surface area-to-volume ratio results in an increase in the rate of diffusion or absorption of substances.
This is particularly important in cells, where a higher ratio allows for more efficient exchange of materials.
What is concentration in the context of diffusion?
Concentration is the amount of substance in a fixed volume.
It is a key factor in determining the rate and direction of diffusion.
What is a concentration gradient?
A concentration gradient is the difference in concentration between two regions.
Particles naturally move down their concentration gradient.
What do all particles have a natural tendency to do?
All particles have a natural tendency to move down their concentration gradient and become evenly spaced out over time.
This tendency drives the process of diffusion.
What is a permeable membrane?
A permeable membrane allows particles of all sizes to pass through freely.
This property is essential for the diffusion of substances across cell membranes.
True or False: Both red and blue ink particles can pass through a permeable membrane.
True
This illustrates how diffusion occurs across a permeable membrane.
What is the process of diffusion in the human respiratory system?
Diffusion of oxygen from the alveoli to red blood cells and diffusion of carbon dioxide from the blood to the alveoli
What is the process of diffusion in plants?
Entry of oxygen from spaces in the soil into root hair cells and removal of carbon dioxide from root hair cells
What is the role of diffusion in the digestive system?
Absorption of digested food from the small intestine to blood capillaries
What is the significance of the surface area-to-volume ratio in cells?
As volume increases, surface area does not increase proportionately, decreasing the ratio and the rate of diffusion
How does the surface area-to-volume ratio affect metabolic activities in cells?
Larger cells cannot diffuse substances in and out quickly enough to support metabolic activities
Calculate the surface area-to-volume ratio for a cube with a side length of 1 cm.
6:1
Calculate the surface area-to-volume ratio for a cube with a side length of 3 cm.
2:1
What factor affects the rate of diffusion based on concentration?
The steeper the concentration gradient, the faster the rate of diffusion
How does the surface area-to-volume ratio influence diffusion?
The larger the surface area-to-volume ratio, the greater the area for substances to pass through, increasing the rate of diffusion
What is the relationship between diffusion distance and the rate of diffusion?
The shorter the diffusion distance, the faster the rate of diffusion
What adaptations do transport cells have to increase their efficiency?
Modified shapes with a high surface area-to-volume ratio
Name a type of cell that has a long protrusion to increase surface area.
Microvilli
What shape modification is seen in red blood cells to enhance their function?
Flattened and biconcave shape
True or False: A high surface area-to-volume ratio increases the efficiency of diffusion.
True
What is 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.
Osmosis specifically refers to the movement of water molecules in the liquid state.
What is the effect of osmosis on plant and animal tissues?
Osmosis affects the turgor pressure in plant cells and can lead to cell shrinkage or swelling in animal cells depending on the surrounding solution.
Turgor pressure is crucial for maintaining the structural integrity of plant cells.
Define water potential.
The tendency for water molecules to move from one region to another.
Water potential is influenced by solute concentration and pressure.
What is the relationship between dilute and concentrated solutions in terms of water potential?
A dilute solution has a higher water potential than a concentrated solution because it has a greater number of water molecules.
Conversely, a concentrated solution has a lower water potential due to fewer water molecules.
What is a water potential gradient?
The difference in water potential between two bodies of liquids.
This gradient drives the movement of water during osmosis.
Which solution has the highest water potential?
Distilled water, as it is made up of 100% water molecules.
Distilled water is the reference point for measuring water potential.
What is a partially permeable membrane?
A membrane that allows smaller particles to pass through but prevents larger particles from passing through.
This property is essential for osmosis to occur.
True or False: Osmosis can describe the movement of water vapour.
False.
Osmosis specifically refers to the movement of water molecules in the liquid state only.
In diffusion, what is the overall direction of particle movement?
Particles move constantly and randomly in all directions with an overall net direction down the concentration gradient.
This is different from the specific directional movement observed in osmosis.
Fill in the blank: A _______ has a greater number of water molecules than a concentrated solution.
dilute solution
Fill in the blank: Water molecules move from a dilute solution to a _______.
concentrated solution
What combination of solutions X and Y will cause the Visking tubing to show the greatest gain in mass after 1 hour?
Solution X: 15% starch solution, Solution Y: Distilled water
This combination creates the highest water potential gradient for osmosis.
Why do starch molecules not move through the Visking tubing?
Starch molecules are too big to move through the partially permeable Visking tubing.
This property is essential for the osmosis experiment.
What is required for the greatest increase in mass in Visking tubing?
The greatest movement of water via osmosis into the Visking tubing.
This is achieved by having the maximum water potential gradient.
What has the highest water potential?
Distilled water.
It is crucial for creating the maximum gradient for osmosis.
What does the movement of water molecules into human cells from tissue fluid exemplify?
Osmosis.
This is a biological example of osmosis in humans.
What does the reabsorption of water in the kidneys demonstrate?
Osmosis.
It is another biological system where osmosis plays a crucial role.
In plants, what is the role of osmosis in relation to photosynthesis?
Transport of water from cell to cell and up to the leaves.
This is essential for maintaining cellular functions during photosynthesis.
How do plant and animal cells behave differently in solutions of varying water potential?
Due to the presence or absence of a cell wall, respectively.
This difference affects their osmotic responses.
Fill in the blank: In a solution with ______, water molecules move into the center of a plant cell.
high water potential.
This causes the cell to become turgid.
In a plant cell, when water molecules move in, what is this process called?
Turgidity.
It results from the accumulation of water in the vacuole.
True or False: Animal cells have a cell wall.
False.
Animal cells lack a cell wall, which affects their osmotic behavior.
What happens to animal cells in a solution where water molecules move in?
They may undergo lysis.
Without a cell wall, animal cells can burst if too much water enters.
What happens to a cell in a solution with a higher water potential than the cytoplasm?
Water molecules move into the cell via osmosis, causing it to swell
This process leads to turgidity in plant cells due to the expansion of the vacuole.
What is turgor pressure?
The pressure exerted by the water in the vacuole against the cell wall in a plant cell
Turgor pressure helps maintain cell structure and prevents bursting.
What happens to plant cells when they become turgid?
The vacuole expands and pushes the cytoplasm against the cell wall, preventing bursting
The presence of the cell wall is crucial for this process.
What occurs in an animal cell when it is placed in a solution with a higher water potential?
The cell membrane bursts due to the build-up of water pressure
Animal cells lack a cell wall, making them more susceptible to osmotic pressure.
What happens to a cell in a solution with a lower water potential than the cytoplasm?
Water molecules move out of the cell via osmosis, causing it to shrink
This process can lead to plasmolysis in plant cells.
What is plasmolysis?
The process where the vacuole shrinks and the cell membrane pulls away from the cell wall in plant cells
A plasmolysed plant cell becomes limp (flaccid).
What occurs to plant cells during plasmolysis?
The cell membrane pulls away from the cell wall, and the cell becomes flaccid
This is a response to water loss via osmosis.
What is crenation?
The process in which spikes appear on the cell membrane of an animal cell when water leaves
Crenation leads to cell death if prolonged.
How does the water potential gradient affect the rate of osmosis?
The steeper the water potential gradient, the faster the rate of osmosis
A greater difference in water potential drives faster movement of water.
What effect does surface area-to-volume ratio have on osmosis?
A larger surface area-to-volume ratio allows for greater area for water molecules to pass through, speeding up osmosis
This principle is particularly important in biological systems.
How does the distance water molecules need to move affect the rate of osmosis?
The shorter the distance, the faster the rate of osmosis
Less time is needed for water molecules to travel shorter distances.
What is turgor pressure and why is it important in plant cells?
Turgor pressure allows the stems and leaves of non-woody plants to stay firm and erect. When plant cells lose turgor, the plant wilts.
What causes the opening and closing of stomata in plants?
Changes in the turgor of the guard cells.
True or False: Osmosis is dependent on the size of solute particles in a solution.
False
What affects osmosis in a solution?
The water potential of the solution.
Fill in the blank: The movement of water molecules is not affected by other _______ in the solution.
particles
What happens to potato strips soaked in a concentrated salt solution?
They become shorter and thinner.
Which statement is true regarding the effect of the concentrated salt solution on potato strips?
C. Changes in the dimensions of the potato strips are due to their decreased water potential.
What cannot diffuse through the cell membrane of potato strips when soaked in salt solution?
Na+ and Cl- ions due to their charges.
What process involves the movement of water molecules out of potato strips into the concentrated salt solution?
Osmosis
How does the movement of water out of the potato strips affect their water potential?
It decreases the water potential of the potato cells.
What is active transport?
Active transport is the process in which energy is used to move particles across a membrane from a region of lower concentration to a region of higher concentration against a concentration gradient.
Active transport is essential for maintaining cellular functions by allowing cells to accumulate necessary substances.
Why is active transport considered an energy-consuming process?
Because it moves substances against a concentration gradient, requiring energy input, typically from ATP.
This energy is crucial for processes like nutrient uptake and waste removal.
What cellular feature is abundant in cells that perform active transport?
Mitochondria
Mitochondria provide the ATP necessary for energy-dependent processes.
Fill in the blank: Active transport moves substances from a region of _______ concentration to a region of higher concentration.
lower
What is an example of active transport in the human excretory system?
Reabsorption of glucose and amino acids in the kidneys.
This process is vital for conserving energy and nutrients.
What is an example of active transport in the human digestive system?
Uptake of glucose by microvilli in the small intestine.
This enables efficient nutrient absorption.
What is an example of active transport in plants?
Uptake of mineral salts by the root hair cells from the soil.
This is crucial for plant nutrition and growth.
What is another example of active transport in plants?
Transport of sucrose from photosynthetic leaves to other parts of the plant through the phloem.
This process helps distribute energy throughout the plant.
True or False: Active transport can occur without the use of energy.
False
Active transport specifically requires energy to function.
What are the two types of movement of molecules mentioned?
Osmosis and Diffusion
These processes differ from active transport as they do not require energy and occur down concentration gradients.
Fill in the blank: The movement of other solutes against a gradient is an example of _______.
active transport
What is described at point A regarding the movement of glucose molecules?
Glucose molecules move from the blood into the tissue fluid.
What is described at point B regarding the movement of glucose molecules?
Glucose molecules move from the tissue fluid into the cells.
What is the effect of a high level of blood albumins on the tissue fluid?
A high level of blood albumins increases osmotic pressure, leading to less tissue fluid being formed.
Fill in the blank: The movement of substances between a blood capillary and body tissue has appeared in examination questions, such as in GCE ‘O’ Level Biology _______.
Oct/Nov 2012 Paper 2 Q5.
What are the chemical elements that make up proteins?
Carbon, hydrogen, oxygen, and nitrogen. Sulfur may be present in some proteins.
What is the main role of proteins in living organisms?
Growth and repair in cells.
What are proteins and polypeptides formed from?
Amino acids.
What are the components of an amino acid?
An amino group (-NH2), a carboxylic acid group (-COOH), and a carbon side chain (R).
How many naturally occurring amino acids are there?
20.
What type of bond is formed when amino acids combine?
Peptide bonds.
What is formed when many amino acids are combined?
A polypeptide.
What is the structure of a complex protein molecule?
One or more polypeptide chains fold together to form a three-dimensional structure.
Fill in the blank: Proteins are made up of _______.
Amino acid monomers.
True or False: The carbon side chain (R) in amino acids can contain sulfur.
True.
