Characteristics of Living Organisms
Cell Structure
Movement in and out of cells
Biomolecules
100
Sensitivity is also known as...
Irritability.
100
What type of cell is this?
Human Cheek Cell
100
Is Osmosis is the net movement of water molecules from a region of lower water potential to a region of higher water potential?
No. Its High water potential to low water potential.
100
Fats are also called as....
Lipids
200
What is the acronym that helps you remember the seven characteristics of living organisms?
MRS.GREN
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.
200
What are some examples of unicellular organisms?
Bacteria, Yeast, Bubble Algae
200
Does Diffusion depend on the energy of the particles?
No. Diffusion is a passive process.
200
What biomolecules did we learn about in B3?
Carbohydrates, Fats, and Proteins.
300
What is the difference between Excretion and Egestion?
Excretion is the removal of toxic and unwanted substances in the body.
Egestion is the is the removal of undigested food that has passed unused through the digestive system.
300
An image of a cell in a microscope is 4 mm, and the magnification of the cell is 80x. What is the actual size of the image? Remember to show (or tell the class) your working and use the right units.
Magnification = Image size/Actual Size.
Actual Size = 4/80
= 0.05 mm or 50 µm
300
Define Diffusion.
the net movement of particles from a region where their concentration is higher to a region where their concentration is lower.
300
What are the functions of Carbohydrates, Proteins, and Fats in the human body?
Carbohydrates act as short-term energy supply, while fats act as long-term energy supply. Fats also act as an insulator, protecting us from cold.
Proteins are used for growth and repair. Enzymes are also made up of proteins.
400
One bacterium needs 20 minutes to divide into two bacteria. If one bacterium weighs 6.25 × 10^−10 g, how much will the bacteria weigh after 24 hours if all the bacteria divide and survive?
24 hours = 1440 minutes
number of divisions = 1440/20 = 72 divisions
number of cells after 72 divisions is 2^72 = 4.72 × 10^21 bacteria.
If one bacterium weighs 6.25 × 10^−10 g, then the bacteria after 24 hours will weigh 2.95 × 10^12 g.
400
Name some differences between plant cells and animal cells, and explain why are they different.
Plant cells have a cell wall and chloroplasts, while animal cells don't. This is because Plant cells have to make their own source of energy (thus the chloroplasts), and a plant has to stay upright (thus the cell wall). Animal cells do not need a wall, and they get energy from other sources, so these organelles are absent.
400
Define Osmosis and name the 4 factor it depends on.
Osmosis is the net movement of water molecules from a region of higher water potential (a dilute solution) to a region of lower water potential (a concentrated solution), through a partially permeable membrane.
The 4 factors are surface area, concentration gradient, temperature, and distance.
400
Describe the Structure of Carbohydrates, Proteins, and Fats.
This are carbohydrate. They are usually in the structure of rings.
This is a molecule of fats. It is glycerol molecule attached to 3 fatty acids.
This is a protein molecule. It is a amino group, a carboxylic group, and a side chain joined by a peptide bond.
500
What are the seven characteristics of living organisms? Define each characteristic, providing at least one example for each.
Movement: an action by an organism causing a change of position or place.
Respiration: The chemical reactions in cells that break down nutrient molecules and release energy.
Sensitivity: The ability to detect and respond to changes in the environment.
Growth: A permanent increase in size and is seen in all living things.
Reproduction: The process that makes more of the same kind of organism.
Excretion: The removal of toxic and unwanted substances from the body.
Nutrition: Taking in materials for energy, growth and development.
Providing at least 1 example for each.
500
Explain how root-hair cells, red-blood cells, palisade cells, and ciliated cells are specialised for their jobs.
Root-Hair Cell: The finger-like extension increases the surface area for absorption of water and minerals.
Palisade Cell: The cell contains many chloroplasts for photosynthesis.
Red-Blood Cell: Its biconcave shape increases the surface area for oxygen to move into or out of the cell. The cell has no nucleus, so there is more room in the cytoplasm for many haemoglobin molecules.
Ciliated Cell: The cell has cilia, which are hair-like extensions which are constantly moving. They sweep mucus upwards, away from the respiratory system.
500
Define and Differentiate between a Turgid, Flaccid, and Plasmolysed Cell.
A plant cell that is placed into pure water or a dilute solution will take in water. The cytoplasm and the vacuole will begin to swell. The strong cell wall prevents the plant cell from bursting as it swells and becomes turgid.
A plant cell that is placed in a concentrated solution will lose water by osmosis, because the water concentration inside the cell is greater than the water concentration outside the cell. The cytoplasm will shrink, so there will be less pressure against the cell wall. The cell will become flaccid (limp and floppy) .
If the solution is concentrated enough, the cytoplasm may shrink so much that the cell membrane is pulled away from the cell wall. This is known as plasmolysis and will probably cause the death of the plant cell.
500
Name all the food tests, the biomolecules that are tested for, the process, and the results.
Benedict's solution is used for testing glucose and simple sugars. The solution is added to the mystery mixture and placed in a water bath for a few minutes. Positive result is red, negative is blue.
Iodine is used for testing Starch. Add a few drops of Iodine in the mystery solution, and shake gently. Positive is dark-blue, negative is orange-brown.
Ethanol is used to test for fats or oils. Add ethanol to the food, grind it, filter it, and put the filtrate in a test tube. The solution will turn cloudy if there is fat or oil.
Biuret test is used to test for proteins. Add a few drops to the mystery mixture and shake it gently. Positive is Purple, Negative is blue.