Cells and Organelles
A living organism consists of just one cell. What term describes it
Unicellular
Which structure controls what enters and leaves a cell
The cell membrane
What is the movement of water across a selectively permeable membrane called
Osmosis
Give the two reasons a multicellular organism needs to produce new body cells
Growth and Repair
Students change the amount of water given to seedlings and measure their height. Identify the independent and dependent variables.
Independent variable—amount of water; dependent variable—seedling height
A cell contains DNA and ribosomes but lacks a nucleus. Is it prokaryotic or eukaryotic
Prokaryotic
A small nonpolar molecule passes directly through the lipid bilayer from high to low concentration. What process occurs
Simple diffusion
An animal cell contains 8% solute, while the surrounding solution contains 3%. Only water can cross. Identify the outside solution and predict water movement
Hypotonic. Water moves into the cell, causing it to swell and possibly burst
A body cell has 24 chromosomes. After normal mitosis and cytokinesis, how many chromosomes will each daughter cell contain
24
Students test two cleaning solutions against a water-only treatment. Identify the control group
Control group—water-only treatment
Name the organelles responsible for building proteins and producing much of a cell’s ATP
Ribosomes build proteins; mitochondria produce much of the ATP
A sugar moves through a carrier protein from higher to lower concentration without using ATP. What process occurs
Facilitated diffusion
An animal cell contains 5% solute, while the surrounding solution contains 16%. Only water can cross. Identify the outside solution and predict the cell’s response
Hypertonic. Water leaves the cell, causing it to shrink
In which phase is DNA copied
S Phase
Write an “If…then…because…” hypothesis about how daily spelling practice might affect the number of words spelled correctly
If daily spelling practice increases, then the number of words spelled correctly will increase
Identify each structure: stores water and nutrients; digests worn-out cell parts; modifies and packages proteins
Vacuole; lysosome; Golgi apparatus
A cell surrounds a food particle and brings it inside in a vesicle. Another vesicle releases material outside. Name both processes
Endocytosis brings material inside; exocytosis releases material outside
A cell and its surroundings both contain 11% solute. What is the solution called, and does water stop moving
Isotonic. Water continues moving in both directions at equal rates, with no net movement
List the four stages of mitosis in order and identify what happens during each
Prophase—chromosomes condense and the spindle forms; metaphase—chromosomes line up in the middle; anaphase—sister chromatids separate; telophase—new nuclei form
A student tests whether music affects puzzle-solving time. One group works with music, and another works in silence. Identify the independent variable, dependent variable, and control group
Independent variable—whether there is music or not; dependent variable—time to complete the puzzle; control group—the group working in silence
A photosynthetic leaf cell has three structures that a typical animal cell lacks. Name them and explain each function
Cell wall—support and protection; chloroplasts—photosynthesis; large central vacuole—water storage and support
A cell uses energy to move ions from an area of lower concentration to an area of higher concentration. Name the mechanism and explain why energy is required
A molecular pump, a form of active transport. Energy is required to move ions against their concentration gradient
A cold person shivers to produce heat. Ripening fruit releases a chemical that causes more fruit to ripen. Identify the feedback type in each example and explain the difference
Shivering is negative feedback because it counteracts a change. Fruit ripening is positive feedback because it amplifies a change
Define programmed cell death, a malignant/benign tumor, and metastasis
Apoptosis is programmed cell death.
A malignant tumor is cancerous and can invade surrounding tissues -> more tumors. A benign tumor are cancerous cells that cluster together/stay in the same place
Metastasis is the spread of cancer from one organ to others
A phospholipid has a hydrophilic head and hydrophobic tails. What do these terms mean
Hydrophilic means attracted to water; hydrophobic means avoiding water