Unit 7: Living Things and Cells
What separates a living thing from a rock, what's inside every one of your cells, and how a plant builds its own food from sunlight.
11 topics · 42 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Characteristics of Living Things
- How it worksHow do scientists use traits like growth, reproduction, and using energy to decide what counts as living?
- How it worksWalk me through checking a mushroom against the living-things checklist, one trait at a time.
- Common mistakeWhy isn't fire alive, even though it grows, moves, needs fuel, and produces waste?
- Going furtherWhat happens to the checklist for alive when you try to apply it to a virus?
Your turn1 of 2
A growing crystal gets bigger and bigger over time, similar to how a plant grows. Does this growth make the crystal count as alive?Cells: The Building Blocks of Life
- How it worksHow do trillions of tiny cells work together to build one single living body?
- Worked exampleFind how a single fertilized egg cell multiplies into over 30 trillion cells that make up an adult human body.
- Common mistakeWhy isn't a cell just an empty little bubble with nothing important inside it?
- Going furtherWhat happens to a cell's number as an organism grows from a baby into an adult?
- Ties togetherHow does one fertilized egg cell dividing over and over connect to how your whole body grew from a baby?
Your turn1 of 2
A single cell doubles through division. Find how many cells result after 7 rounds of doubling (2 to the power of 7).Plant Cells vs. Animal Cells
- How it worksHow do the cell wall and chloroplasts inside a plant cell give it powers an animal cell doesn't have?
- Worked exampleFind which parts are shared by both plant and animal cells and which parts only plant cells have: nucleus, cell wall, chloroplast, cell membrane.
- Common mistakeWhy doesn't every plant cell need to be green just because plants have chloroplasts?
Your turn1 of 2
Which of these is found in BOTH plant cells and animal cells: the cell wall, or the nucleus?Photosynthesis
- How it worksHow do a plant's leaves combine sunlight, water, and carbon dioxide into sugar and oxygen?
- How it worksWalk me through the path water and carbon dioxide take from the roots and air into a leaf's chloroplasts.
- Common mistakeWhy don't plants get most of their food, their actual mass, from the soil?
- Going furtherWhat happens to a plant's photosynthesis rate when it's moved into a dark closet?
Your turn1 of 2
Why don't plants need to go find and eat food the way animals do, even though they're clearly alive and growing?Parts of a Plant
- How it worksHow do roots, stems, leaves, and flowers each do a completely different job for the same plant?
- Common mistakeWhy aren't roots just there to hold the plant in the ground, with no other job to do?
- Going furtherWhat happens to a plant if its stem's water-carrying tubes get blocked?
Your turn1 of 2
Why does a plant need to be built with roots reaching down into the soil AND leaves reaching up toward the sun at the same time?Animal Classification
- How it worksHow do traits like backbones, warm or cold blood, and how babies are born sort animals into groups?
- Worked exampleFind which group each animal belongs to: a frog, a shark, an eagle, and a snake, sorted by amphibian, fish, bird, or reptile.
- Common mistakeWhy isn't a dolphin a fish, even though it swims and lives its whole life in the ocean?
- Going furtherWhat happens to an animal's classification when it has a backbone but doesn't fit neatly into any single familiar group, like a platypus?
Your turn1 of 2
A frog, a shark, an eagle, and a snake need to be sorted by group. Which one belongs in the group 'amphibian'?Life Cycles
- How it worksHow does an organism repeat the same stages, from birth to reproducing to death, generation after generation?
- Common mistakeWhy doesn't every animal's life cycle look like a human's, with one steady body shape the whole way through?
- Going furtherWhat happens to a life cycle's length when you compare a mayfly living one day to a tortoise living 100 years?
- Ties togetherHow does a life cycle's repeating stages connect to how metamorphosis fits in as one dramatic kind of life cycle?
Your turn1 of 2
Why does a tiny acorn already contain the complete blueprint for a giant oak tree?Metamorphosis
- How it worksHow does a tadpole's body rebuild itself, growing legs and losing its tail and gills, into a frog?
- How it worksWalk me through complete metamorphosis in an insect, from egg to larva to pupa to adult.
- Common mistakeWhy isn't a caterpillar just growing up the same slow way a puppy grows into a dog?
- Going furtherWhat happens to metamorphosis in insects that skip the pupa stage, like grasshoppers?
Your turn1 of 2
Why does a caterpillar have to completely break down its body inside a chrysalis before becoming a butterfly?Adaptations
- How it worksHow does a trait that helps an animal survive and reproduce spread through a population over generations?
- Common mistakeWhy doesn't an individual animal choose to grow an adaptation just because it needs one?
- Going furtherWhat happens to a polar bear's white-fur adaptation if its icy habitat disappears?
- Ties togetherHow does an adaptation like camouflage connect to natural selection acting across many generations?
Your turn1 of 2
Why does a polar bear's white fur and thick fat make so much more sense once you picture it hunting on Arctic ice?Inherited vs. Learned Traits
- How it worksHow do you tell an inherited trait passed down in genes from a learned behavior picked up through experience?
- Worked exampleFind which traits are inherited and which are learned: eye color, riding a bike, having five fingers, speaking English.
- Common mistakeWhy doesn't practicing a skill your whole life change the genes you pass on to your kids?
Your turn1 of 2
Which of these is an INHERITED trait, not a learned one: eye color, or riding a bike?Heredity: Traits from Parents
- How it worksHow do genes from two parents combine to decide a trait like eye color in their child?
- Common mistakeWhy doesn't a trait always show up in a child just because one parent has it?
- Going furtherWhat happens to the traits passed down when you follow them across three generations in a family tree?
- Ties togetherHow does heredity connect to how adaptations spread through a whole population over time?
Your turn1 of 2
Why do you share some traits with your mom, some with your dad, and some that look like neither one?