Cell Theory
What is the basic unit of life?
A cell
Which cell part controls what enters and leaves the cell?
Cell membrane
Which type of cell has chloroplasts?
Plant Cell
Are bacteria generally unicellular or multicellular?
Unicellular
What do we call a scientific question that can be investigated using observations or measurements?
A testable question
What do we call an organism made of only one cell?
Unicellular
Which organelle builds proteins?
Ribosomes
Name one structure found in both plant and animal cells.
Cell membrane, cytoplasm, nucleus, or mitochondria
What molecule carries genetic instructions in cells and many viruses?
DNA
A scientist changes the temperature of water to see how it affects yeast. What is the independent variable?
Temperature
According to Cell Theory, where do new cells come from?
Pre existing cells
Which organelle contains most of a cell's DNA and helps control cell activities?
Nucleus
What is the job of chloroplasts?
They use light energy to make food through photosynthesis.
What is one major difference between bacteria and viruses?
Bacteria are cells that can reproduce independently under suitable conditions; viruses need host cells to make more copies.
The scientist measures how much gas the yeast produces. What is the dependent variable?
The amount of gas produced
A scientist finds an organism made of many cells that work together. What type of organism is it, and what is one advantage of having many cells?
Multicellular; cells can specialize in different jobs.
A cell needs more usable energy to carry out its activities. Which organelle helps release energy from food?
Mitochondria
A student observes a cell with a nucleus, mitochondria, and a cell membrane. The student concludes that it must be an animal cell. Why is this conclusion incorrect?
Plant cells also have a nucleus, mitochondria, and a cell membrane. The student needs more evidence, such as checking for a cell wall or chloroplasts.
A scientist discovers a microscopic organism that can grow and reproduce on its own under the right conditions. Would this be stronger evidence for a bacterium or a virus? Explain.
A bacterium. Bacteria are cells that can reproduce independently under suitable conditions, while viruses require a host cell to make more copies.
Two identical plants receive different amounts of fertilizer, but one also receives more sunlight. Why is it difficult to determine whether fertilizer caused the difference in growth?
Sunlight is another variable that could affect growth, so the investigation is not a fair comparison.
A student claims that a single celled organism cannot survive because it does not have specialized cells for every job. Explain why the student is incorrect.
Its one cell performs all the functions needed for survival.
A cell has working mitochondria and a nucleus, but its ribosomes stop functioning. Explain two ways this could affect the cell.
It could no longer make proteins properly, affecting cell functions, growth, and repair.
A student observes two unknown cells. Cell A has chloroplasts and a cell wall. Cell B has neither. What can the student conclude, and why is the evidence stronger than looking at shape alone?
Cell A is most likely a plant cell. Chloroplasts and a cell wall are more useful identifying structures than shape alone, which can vary.
A scientist observes a microscopic organism that contains DNA and can reproduce on its own. Another microscopic particle contains genetic material but can only make copies of itself inside a host cell. Explain which one is more likely a bacterium and which one is more likely a virus, using evidence.
The first is more likely a bacterium because it can reproduce independently. The second is more likely a virus because it needs a host cell to make copies of itself.
A scientist tests three different temperatures on yeast. The results are 2 mL, 7 mL, and 4 mL of gas produced. Explain what the scientist can conclude and why the scientist should repeat the experiment.
The middle temperature tested produced the most gas in these trials. Repeating the experiment helps determine whether the pattern is consistent and reduces the effect of random error.