Ecology & the Human Body

Ecosystems, food webs and biodiversity, plus the organs and systems that keep the human body running.

An ecosystem includes all living organisms and their physical environment.
Producers like plants make their own food through photosynthesis.
Consumers obtain energy by eating other organisms.
Decomposers break down dead matter and recycle nutrients.
A food chain shows how energy passes between organisms.
Biodiversity refers to the variety of life within an ecosystem.
The human heart pumps blood throughout the circulatory system.
The lungs exchange oxygen and carbon dioxide during breathing.
The brain is the control center of the human nervous system.
The skeleton provides structure and protects internal organs.
The stomach uses acid and enzymes to digest food.
Red blood cells carry oxygen from the lungs to the body's tissues.
The liver filters toxins and helps process nutrients.
The immune system defends the body against infections.
Photosynthesis by plants supplies much of Earth's oxygen.
The kidneys filter waste from the blood to form urine.
Ecology is the scientific study of interactions between organisms and their environment.
The term ecology was coined by German biologist Ernst Haeckel in 1866.
A population is a group of one species living in a particular area.
A community includes all the populations of different species in an area.
The biosphere is the global sum of all ecosystems on Earth.
A habitat is the natural environment where an organism lives.
A niche describes an organism's role and position within its ecosystem.
Herbivores are consumers that eat only plants for their energy.
Carnivores are consumers that obtain energy by eating other animals.
Omnivores eat both plants and animals for energy.
A trophic level represents a step in the flow of energy through an ecosystem.
Primary producers occupy the first trophic level in a food chain.
Only about ten percent of energy passes from one trophic level to the next.
A food web shows many interconnected food chains in an ecosystem.
An apex predator sits at the top of its food chain with no natural predators.
Bacteria and fungi are the main decomposers in most ecosystems.
The carbon cycle moves carbon between the atmosphere, organisms, and the earth.
The nitrogen cycle converts nitrogen into forms usable by living organisms.
Nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia in soil.
The water cycle includes evaporation, condensation, and precipitation.
Photosynthesis converts carbon dioxide and water into glucose using sunlight.
Cellular respiration releases energy from glucose using oxygen.
Chlorophyll is the green pigment plants use to capture light energy.
Symbiosis describes a close, long-term interaction between two different species.
Mutualism is a relationship where both species benefit from each other.
Commensalism benefits one species while the other is unaffected.
Parasitism benefits one organism at the expense of its host.
Predation is an interaction where one organism hunts and eats another.
Competition occurs when organisms vie for the same limited resources.
A keystone species has a large effect on its ecosystem relative to its abundance.
Carrying capacity is the maximum population an environment can sustainably support.
A biome is a large region defined by its climate, plants, and animals.
Tropical rainforests contain the highest biodiversity of any land biome.
Deserts are biomes characterized by very low annual rainfall.
Tundra is a cold biome with frozen subsoil called permafrost.
Succession is the gradual change in species composition of a community over time.
Primary succession begins on bare rock with no existing soil.
Secondary succession occurs in areas where soil already exists after disturbance.
An invasive species spreads rapidly and harms native ecosystems.
Biomass is the total mass of living organisms in a given area.
An ecological pyramid shows energy, biomass, or numbers across trophic levels.
Abiotic factors are nonliving parts of an ecosystem like sunlight and water.
Biotic factors are the living parts of an ecosystem.
Eutrophication is excess nutrient enrichment that depletes oxygen in water.
A food chain typically begins with a producer and ends with a top predator.
Detritivores like earthworms feed on dead organic material.
The ozone layer absorbs much of the sun's harmful ultraviolet radiation.
Deforestation reduces biodiversity and increases atmospheric carbon dioxide.
Conservation biology aims to protect species and ecosystems from extinction.
Endemic species are found naturally in only one geographic region.
Migration is the seasonal movement of animals between regions.
Pollination transfers pollen and enables many plants to reproduce.
The human body is organized into cells, tissues, organs, and organ systems.
The cell is the basic structural and functional unit of life.
The nucleus contains a cell's genetic material in the form of DNA.
Mitochondria are the organelles that produce energy within cells.
The cell membrane controls what enters and leaves the cell.
DNA carries the genetic instructions for building and maintaining an organism.
Genes are segments of DNA that code for specific proteins.
The human body contains roughly 37 trillion cells.
The skeletal system of an adult human contains 206 bones.
Bone marrow inside bones produces red and white blood cells.
Cartilage is flexible connective tissue found at the ends of bones.
Joints are the points where two or more bones meet.
Ligaments are tough tissues that connect bone to bone at joints.
Tendons are strong tissues that connect muscle to bone.
The human body has more than 600 skeletal muscles.
Skeletal muscles work in pairs to move parts of the body.
Smooth muscle lines internal organs and works involuntarily.
Cardiac muscle forms the wall of the heart.
The diaphragm is a muscle that contracts to help the lungs draw in air.
The trachea, or windpipe, carries air to and from the lungs.
Alveoli are tiny air sacs in the lungs where gas exchange occurs.
The bronchi are tubes that branch from the trachea into the lungs.
Oxygen diffuses from the alveoli into the blood in the lungs.
Carbon dioxide is a waste product removed from the body by exhaling.
The heart has four chambers: two atria and two ventricles.
The right side of the heart pumps blood to the lungs.
The left side of the heart pumps blood to the rest of the body.
Arteries are blood vessels that carry blood away from the heart.
Veins are blood vessels that carry blood back toward the heart.
Capillaries are tiny vessels where exchange of gases and nutrients occurs.
Blood is composed of plasma, red cells, white cells, and platelets.
Plasma is the liquid part of blood that carries cells and nutrients.
White blood cells help defend the body against infection.
Platelets help the blood to clot and stop bleeding.
Hemoglobin is the iron-rich protein in red blood cells that binds oxygen.
The average adult human has about five liters of blood.
The heart beats roughly 100,000 times per day.
Blood pressure is the force of blood against the walls of arteries.
Digestion begins in the mouth where saliva starts breaking down food.
The esophagus carries food from the throat to the stomach.
The small intestine absorbs most nutrients from digested food.
The large intestine absorbs water and forms solid waste.
The pancreas produces enzymes and the hormone insulin.
The gallbladder stores bile until it is needed for digestion.
Bile produced by the liver helps digest fats.
Villi are tiny projections that increase the surface area of the small intestine.
Enzymes are proteins that speed up chemical reactions in the body.
Insulin regulates the level of glucose in the blood.
The nervous system is made up of the brain, spinal cord, and nerves.
Neurons are specialized cells that transmit nerve signals.
The spinal cord connects the brain to the rest of the body.
The cerebrum is the largest part of the brain and controls thought.
The cerebellum coordinates voluntary movement, posture, and balance in the body.
The brainstem controls vital functions like breathing and heartbeat.
A reflex is an automatic response that does not require conscious thought.
The central nervous system includes the brain and spinal cord.
The peripheral nervous system includes nerves outside the brain and spinal cord.
Sensory neurons carry signals from the body to the brain.
Motor neurons carry signals from the brain to muscles and glands.
A synapse is the gap across which nerve signals are transmitted.
Neurotransmitters are chemicals that carry signals between neurons.
The endocrine system uses hormones to regulate body functions.
Hormones are chemical messengers released into the bloodstream.
The pituitary gland is often called the master gland of the body.
The thyroid gland releases hormones that regulate the body's metabolism.
Adrenaline is a hormone that prepares the body for fight-or-flight responses.
The adrenal glands sit on top of the kidneys.
The urinary system removes liquid waste from the body.
Nephrons are the microscopic filtering units within the kidneys.
Urine travels from the kidneys to the bladder through the ureters.
The bladder stores urine until it is released from the body.
The skin is the largest organ of the human body.
The skin protects the body and helps regulate temperature.
Sweat glands in the skin help cool the body through evaporation.
Melanin is the pigment that gives skin and hair their color.
The epidermis is the outer layer of the skin.
The dermis lies beneath the epidermis and contains blood vessels.
The eye detects light and sends visual signals to the brain.
The retina contains cells that respond to light at the back of the eye.
The pupil controls how much light enters the eye.
The lens of the eye focuses light onto the retina.
The ear detects sound and helps maintain balance.
The cochlea in the inner ear converts sound into nerve signals.
The eardrum vibrates in response to sound waves.
The tongue contains taste buds that detect different flavors.
The nose detects smell through receptors in the nasal cavity.
The immune system includes white blood cells and lymph nodes.
Antibodies are proteins that identify and neutralize harmful invaders.
Antigens are molecules that trigger an immune response.
Vaccines train the immune system to recognize specific pathogens.
Lymph is a fluid that carries immune cells throughout the body.
The spleen filters blood and helps fight infection.
The thymus is where certain immune cells called T cells mature.
Pathogens are microorganisms such as bacteria and viruses that cause disease.
Bacteria are single-celled organisms, some of which cause disease.
Viruses are tiny infectious agents that replicate inside living cells.
Fever is a rise in body temperature that helps fight infection.
Inflammation is the body's response to injury or infection.
The reproductive system enables organisms to produce offspring.
Homeostasis is the maintenance of stable internal body conditions.
The normal human body temperature is about 37 degrees Celsius.
Proteins are essential nutrients made of building blocks called amino acids.
Carbohydrates are the body's main source of quick energy.
Fats store energy and help absorb certain vitamins.
Vitamins are nutrients the body needs in small amounts to function.
Minerals like calcium and iron are essential for body processes.
Calcium is needed for strong bones and teeth.
Iron is needed to make hemoglobin in red blood cells.
Water makes up roughly 60 percent of the adult human body.
Glucose is a simple sugar used by cells for energy.
Metabolism is the sum of all chemical reactions in the body.
ATP is the molecule that stores and transfers energy in cells.
Cells divide through a process called mitosis to grow and repair tissue.
Chromosomes are structures that carry genetic information in cells.
Humans typically have 46 chromosomes in most body cells.
The liver stores glucose in the form of glycogen.
Teeth mechanically break food into smaller pieces for digestion.
The appendix is a small pouch attached to the large intestine.
Hair and nails are made mostly of a protein called keratin.
Blood type is determined by molecules on the surface of red blood cells.
The four main human blood types are A, B, AB, and O.
Antibiotics are medicines that kill or stop the growth of bacteria.
Genetic information passes from parents to offspring through DNA.
An ecosystem can be as small as a pond or as large as a forest.
Energy in most ecosystems originally comes from the sun.
Scavengers feed on the remains of dead animals.
Adaptations are traits that help organisms survive in their environment.
Camouflage helps organisms blend into their surroundings to avoid predators.
Extinction is the permanent disappearance of a species from Earth.
Wetlands filter water and provide habitat for many species.
Plankton form the base of many aquatic food chains.
Soil contains organisms that recycle nutrients for plant growth.

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Ecology & the Human Body

Ecosystems, food webs and biodiversity, plus the organs and systems that keep the human body running.

An ecosystem includes all living organisms and their physical environment.
Producers like plants make their own food through photosynthesis.
Consumers obtain energy by eating other organisms.
Decomposers break down dead matter and recycle nutrients.
A food chain shows how energy passes between organisms.
Biodiversity refers to the variety of life within an ecosystem.
The human heart pumps blood throughout the circulatory system.
The lungs exchange oxygen and carbon dioxide during breathing.
The brain is the control center of the human nervous system.
The skeleton provides structure and protects internal organs.
The stomach uses acid and enzymes to digest food.
Red blood cells carry oxygen from the lungs to the body's tissues.
The liver filters toxins and helps process nutrients.
The immune system defends the body against infections.
Photosynthesis by plants supplies much of Earth's oxygen.
The kidneys filter waste from the blood to form urine.
Ecology is the scientific study of interactions between organisms and their environment.
The term ecology was coined by German biologist Ernst Haeckel in 1866.
A population is a group of one species living in a particular area.
A community includes all the populations of different species in an area.
The biosphere is the global sum of all ecosystems on Earth.
A habitat is the natural environment where an organism lives.
A niche describes an organism's role and position within its ecosystem.
Herbivores are consumers that eat only plants for their energy.
Carnivores are consumers that obtain energy by eating other animals.
Omnivores eat both plants and animals for energy.
A trophic level represents a step in the flow of energy through an ecosystem.
Primary producers occupy the first trophic level in a food chain.
Only about ten percent of energy passes from one trophic level to the next.
A food web shows many interconnected food chains in an ecosystem.
An apex predator sits at the top of its food chain with no natural predators.
Bacteria and fungi are the main decomposers in most ecosystems.
The carbon cycle moves carbon between the atmosphere, organisms, and the earth.
The nitrogen cycle converts nitrogen into forms usable by living organisms.
Nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia in soil.
The water cycle includes evaporation, condensation, and precipitation.
Photosynthesis converts carbon dioxide and water into glucose using sunlight.
Cellular respiration releases energy from glucose using oxygen.
Chlorophyll is the green pigment plants use to capture light energy.
Symbiosis describes a close, long-term interaction between two different species.
Mutualism is a relationship where both species benefit from each other.
Commensalism benefits one species while the other is unaffected.
Parasitism benefits one organism at the expense of its host.
Predation is an interaction where one organism hunts and eats another.
Competition occurs when organisms vie for the same limited resources.
A keystone species has a large effect on its ecosystem relative to its abundance.
Carrying capacity is the maximum population an environment can sustainably support.
A biome is a large region defined by its climate, plants, and animals.
Tropical rainforests contain the highest biodiversity of any land biome.
Deserts are biomes characterized by very low annual rainfall.
Tundra is a cold biome with frozen subsoil called permafrost.
Succession is the gradual change in species composition of a community over time.
Primary succession begins on bare rock with no existing soil.
Secondary succession occurs in areas where soil already exists after disturbance.
An invasive species spreads rapidly and harms native ecosystems.
Biomass is the total mass of living organisms in a given area.
An ecological pyramid shows energy, biomass, or numbers across trophic levels.
Abiotic factors are nonliving parts of an ecosystem like sunlight and water.
Biotic factors are the living parts of an ecosystem.
Eutrophication is excess nutrient enrichment that depletes oxygen in water.
A food chain typically begins with a producer and ends with a top predator.
Detritivores like earthworms feed on dead organic material.
The ozone layer absorbs much of the sun's harmful ultraviolet radiation.
Deforestation reduces biodiversity and increases atmospheric carbon dioxide.
Conservation biology aims to protect species and ecosystems from extinction.
Endemic species are found naturally in only one geographic region.
Migration is the seasonal movement of animals between regions.
Pollination transfers pollen and enables many plants to reproduce.
The human body is organized into cells, tissues, organs, and organ systems.
The cell is the basic structural and functional unit of life.
The nucleus contains a cell's genetic material in the form of DNA.
Mitochondria are the organelles that produce energy within cells.
The cell membrane controls what enters and leaves the cell.
DNA carries the genetic instructions for building and maintaining an organism.
Genes are segments of DNA that code for specific proteins.
The human body contains roughly 37 trillion cells.
The skeletal system of an adult human contains 206 bones.
Bone marrow inside bones produces red and white blood cells.
Cartilage is flexible connective tissue found at the ends of bones.
Joints are the points where two or more bones meet.
Ligaments are tough tissues that connect bone to bone at joints.
Tendons are strong tissues that connect muscle to bone.
The human body has more than 600 skeletal muscles.
Skeletal muscles work in pairs to move parts of the body.
Smooth muscle lines internal organs and works involuntarily.
Cardiac muscle forms the wall of the heart.
The diaphragm is a muscle that contracts to help the lungs draw in air.
The trachea, or windpipe, carries air to and from the lungs.
Alveoli are tiny air sacs in the lungs where gas exchange occurs.
The bronchi are tubes that branch from the trachea into the lungs.
Oxygen diffuses from the alveoli into the blood in the lungs.
Carbon dioxide is a waste product removed from the body by exhaling.
The heart has four chambers: two atria and two ventricles.
The right side of the heart pumps blood to the lungs.
The left side of the heart pumps blood to the rest of the body.
Arteries are blood vessels that carry blood away from the heart.
Veins are blood vessels that carry blood back toward the heart.
Capillaries are tiny vessels where exchange of gases and nutrients occurs.
Blood is composed of plasma, red cells, white cells, and platelets.
Plasma is the liquid part of blood that carries cells and nutrients.
White blood cells help defend the body against infection.
Platelets help the blood to clot and stop bleeding.
Hemoglobin is the iron-rich protein in red blood cells that binds oxygen.
The average adult human has about five liters of blood.
The heart beats roughly 100,000 times per day.
Blood pressure is the force of blood against the walls of arteries.
Digestion begins in the mouth where saliva starts breaking down food.
The esophagus carries food from the throat to the stomach.
The small intestine absorbs most nutrients from digested food.
The large intestine absorbs water and forms solid waste.
The pancreas produces enzymes and the hormone insulin.
The gallbladder stores bile until it is needed for digestion.
Bile produced by the liver helps digest fats.
Villi are tiny projections that increase the surface area of the small intestine.
Enzymes are proteins that speed up chemical reactions in the body.
Insulin regulates the level of glucose in the blood.
The nervous system is made up of the brain, spinal cord, and nerves.
Neurons are specialized cells that transmit nerve signals.
The spinal cord connects the brain to the rest of the body.
The cerebrum is the largest part of the brain and controls thought.
The cerebellum coordinates voluntary movement, posture, and balance in the body.
The brainstem controls vital functions like breathing and heartbeat.
A reflex is an automatic response that does not require conscious thought.
The central nervous system includes the brain and spinal cord.
The peripheral nervous system includes nerves outside the brain and spinal cord.
Sensory neurons carry signals from the body to the brain.
Motor neurons carry signals from the brain to muscles and glands.
A synapse is the gap across which nerve signals are transmitted.
Neurotransmitters are chemicals that carry signals between neurons.
The endocrine system uses hormones to regulate body functions.
Hormones are chemical messengers released into the bloodstream.
The pituitary gland is often called the master gland of the body.
The thyroid gland releases hormones that regulate the body's metabolism.
Adrenaline is a hormone that prepares the body for fight-or-flight responses.
The adrenal glands sit on top of the kidneys.
The urinary system removes liquid waste from the body.
Nephrons are the microscopic filtering units within the kidneys.
Urine travels from the kidneys to the bladder through the ureters.
The bladder stores urine until it is released from the body.
The skin is the largest organ of the human body.
The skin protects the body and helps regulate temperature.
Sweat glands in the skin help cool the body through evaporation.
Melanin is the pigment that gives skin and hair their color.
The epidermis is the outer layer of the skin.
The dermis lies beneath the epidermis and contains blood vessels.
The eye detects light and sends visual signals to the brain.
The retina contains cells that respond to light at the back of the eye.
The pupil controls how much light enters the eye.
The lens of the eye focuses light onto the retina.
The ear detects sound and helps maintain balance.
The cochlea in the inner ear converts sound into nerve signals.
The eardrum vibrates in response to sound waves.
The tongue contains taste buds that detect different flavors.
The nose detects smell through receptors in the nasal cavity.
The immune system includes white blood cells and lymph nodes.
Antibodies are proteins that identify and neutralize harmful invaders.
Antigens are molecules that trigger an immune response.
Vaccines train the immune system to recognize specific pathogens.
Lymph is a fluid that carries immune cells throughout the body.
The spleen filters blood and helps fight infection.
The thymus is where certain immune cells called T cells mature.
Pathogens are microorganisms such as bacteria and viruses that cause disease.
Bacteria are single-celled organisms, some of which cause disease.
Viruses are tiny infectious agents that replicate inside living cells.
Fever is a rise in body temperature that helps fight infection.
Inflammation is the body's response to injury or infection.
The reproductive system enables organisms to produce offspring.
Homeostasis is the maintenance of stable internal body conditions.
The normal human body temperature is about 37 degrees Celsius.
Proteins are essential nutrients made of building blocks called amino acids.
Carbohydrates are the body's main source of quick energy.
Fats store energy and help absorb certain vitamins.
Vitamins are nutrients the body needs in small amounts to function.
Minerals like calcium and iron are essential for body processes.
Calcium is needed for strong bones and teeth.
Iron is needed to make hemoglobin in red blood cells.
Water makes up roughly 60 percent of the adult human body.
Glucose is a simple sugar used by cells for energy.
Metabolism is the sum of all chemical reactions in the body.
ATP is the molecule that stores and transfers energy in cells.
Cells divide through a process called mitosis to grow and repair tissue.
Chromosomes are structures that carry genetic information in cells.
Humans typically have 46 chromosomes in most body cells.
The liver stores glucose in the form of glycogen.
Teeth mechanically break food into smaller pieces for digestion.
The appendix is a small pouch attached to the large intestine.
Hair and nails are made mostly of a protein called keratin.
Blood type is determined by molecules on the surface of red blood cells.
The four main human blood types are A, B, AB, and O.
Antibiotics are medicines that kill or stop the growth of bacteria.
Genetic information passes from parents to offspring through DNA.
An ecosystem can be as small as a pond or as large as a forest.
Energy in most ecosystems originally comes from the sun.
Scavengers feed on the remains of dead animals.
Adaptations are traits that help organisms survive in their environment.
Camouflage helps organisms blend into their surroundings to avoid predators.
Extinction is the permanent disappearance of a species from Earth.
Wetlands filter water and provide habitat for many species.
Plankton form the base of many aquatic food chains.
Soil contains organisms that recycle nutrients for plant growth.

Learn this lesson, not just read it

Load these facts straight into the free Class Coupon Speed Learning app — they become fast, playful study activities with audio and translation in 100+ languages.

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