7th Grade Life Science – Winter Benchmark Practice Flashcard

Front

A student wants to test whether the amount of sunlight affects the growth rate of bean plants. What is the best hypothesis?

Back

If plants receive more sunlight, then they will grow taller because light is needed for photosynthesis.

Answer explanation

The best hypothesis is that more sunlight leads to taller plants due to its role in photosynthesis, directly linking sunlight to growth, unlike the other options which are more general or unrelated.

Front

What is the independent variable in an experiment to see how temperature affects mold growth on bread?

Back

The temperature of the environment

Answer explanation

The independent variable is the factor that is changed in an experiment. In this case, the temperature of the environment is manipulated to observe its effect on mold growth, making it the independent variable.

Front

Which action would make an investigation more reliable?

Back

Repeating the experiment many times

Answer explanation

Repeating the experiment many times increases reliability by ensuring that results are consistent and not due to random chance. This helps to confirm findings and reduces the impact of anomalies.

Front

A graph shows that the number of aquatic insects increases as water oxygen levels increase. What is the best conclusion?

Back

More aquatic insects are found where oxygen levels are higher.

Answer explanation

The graph indicates a positive correlation between aquatic insect numbers and oxygen levels, suggesting that higher oxygen levels support more aquatic insects. Thus, the best conclusion is that more aquatic insects are found where oxygen levels are higher.

Front

Which structure controls what enters and leaves a cell?

Back

Cell membrane

Answer explanation

The cell membrane controls what enters and leaves a cell by acting as a selective barrier, allowing certain substances to pass while blocking others. This is essential for maintaining the cell's internal environment.

Front

A cell contains chloroplasts, a cell wall, a large vacuole, and a nucleus. What type of cell is it?

Back

Plant cell

Answer explanation

The presence of chloroplasts, a cell wall, and a large vacuole indicates that the cell is a plant cell, as these structures are characteristic of plant cells and not found in bacterial, animal, or fungal cells.

Front

Which observation helped scientists form modern cell theory?

Back

Cells divide to form new cells.

Answer explanation

The observation that cells divide to form new cells is fundamental to modern cell theory, which states that all living organisms are composed of cells and that all cells arise from pre-existing cells.

Front

What are the levels of cell organization from the simplest to the most complex?

Back

Cell → Tissue → Organ → Organ system → Organism

Answer explanation

The correct sequence is Cell → Tissue → Organ → Organ system → Organism, as it progresses from the simplest unit (cell) to the most complex (organism), reflecting the hierarchical organization in biological systems.

Front

What is the basic unit of life?

Back

Cell

Front

A nerve cell is an example of—

Back

a cell that is part of a multicellular organism

Answer explanation

A nerve cell, or neuron, is a specialized cell that transmits signals in the nervous system. It is not a complete organism, tissue, or organ system, but rather a cell that is part of a multicellular organism.