1. The Characteristics of Living Things
The seven characteristics shared by all living organisms are summarized
by the acronym MRS. GREN:
M - Movement: All living things move, whether it's an animal
walking, a plant's roots growing, or a single-celled organism
shifting its shape.
R - Respiration: This is a chemical process where organisms
convert glucose (food) into energy for their activities. This is
not the same as breathing, which is the physical act of
inhaling and exhaling.
S - Sensitivity: Organisms detect and respond to changes in
their environment, known as stimuli. For example, a plant
grows towards sunlight, and a human pulls their hand away
from a hot surface.
G - Growth: Living things increase in size or complexity. This
can be seen in a seedling growing into a tree or a child
growing into an adult.
R - Reproduction: This is the process of creating new
individuals to ensure the survival of the species. This can
happen through seeds, spores, or by making identical copies
of themselves (plantlets).
E - Excretion: The removal of waste products from the body.
This includes waste from metabolic processes, such as the
carbon dioxide we exhale and the urea in our urine.
N - Nutrition: The intake of food to provide energy and the
raw materials needed for growth and repair.
2. Organ Systems: Plants and Humans
Both plants and humans are complex organisms with specialized parts, or
organs, that work together in systems.
Roots: The root system anchors the plant and absorbs water and
minerals from the soil. Some roots, like carrots, also store food.
There are two main types: taproots, with one large central root,
and fibrous roots, which have a dense network of smaller roots.
Stem: The stem provides support for leaves and flowers and acts
as a transport system for water and nutrients.
Leaves: The primary site of photosynthesis, where the plant
makes its own food using sunlight.
Leaves also regulate gas exchange (carbon dioxide and oxygen)
and water loss.
, Photosynthesis: Carbon dioxide + Water + Light energy → Glucose +
Oxygen.
Flowers: These contain the reproductive organs and are often
brightly colored to attract pollinators like bees or butterflies.
3.Human System
Humans have several interconnected systems that perform specific
functions.
Skeletal System: Provides protection for soft organs (like the
skull for the brain), support for the body, and allows for
movement with the help of muscles. It's made of bones, connected
by joints that can be fused (like in the skull) or movable (like the
hip's ball-and-socket joint). Ligaments hold bones together, and
cartilage and synovial fluid reduce friction at joints.
Muscular System: Composed of muscles that contract and
expand to cause movement. Antagonistic muscle pairs (like the
biceps and triceps) work in opposition. Smooth muscle is found in
organs like the stomach, and cardiac muscle makes up the heart.
Circulatory System: The heart pumps blood through arteries
(carrying blood away from the heart) and veins (carrying blood
back to the heart). The system transports oxygen, nutrients, and
hormones throughout the body. Your pulse is a measure of your
heart rate.
Respiratory System: Facilitates the exchange of gases. Air enters
through the nose/mouth, travels down the trachea and bronchi,
and reaches the lungs. Here, oxygen enters the bloodstream, and
The seven characteristics shared by all living organisms are summarized
by the acronym MRS. GREN:
M - Movement: All living things move, whether it's an animal
walking, a plant's roots growing, or a single-celled organism
shifting its shape.
R - Respiration: This is a chemical process where organisms
convert glucose (food) into energy for their activities. This is
not the same as breathing, which is the physical act of
inhaling and exhaling.
S - Sensitivity: Organisms detect and respond to changes in
their environment, known as stimuli. For example, a plant
grows towards sunlight, and a human pulls their hand away
from a hot surface.
G - Growth: Living things increase in size or complexity. This
can be seen in a seedling growing into a tree or a child
growing into an adult.
R - Reproduction: This is the process of creating new
individuals to ensure the survival of the species. This can
happen through seeds, spores, or by making identical copies
of themselves (plantlets).
E - Excretion: The removal of waste products from the body.
This includes waste from metabolic processes, such as the
carbon dioxide we exhale and the urea in our urine.
N - Nutrition: The intake of food to provide energy and the
raw materials needed for growth and repair.
2. Organ Systems: Plants and Humans
Both plants and humans are complex organisms with specialized parts, or
organs, that work together in systems.
Roots: The root system anchors the plant and absorbs water and
minerals from the soil. Some roots, like carrots, also store food.
There are two main types: taproots, with one large central root,
and fibrous roots, which have a dense network of smaller roots.
Stem: The stem provides support for leaves and flowers and acts
as a transport system for water and nutrients.
Leaves: The primary site of photosynthesis, where the plant
makes its own food using sunlight.
Leaves also regulate gas exchange (carbon dioxide and oxygen)
and water loss.
, Photosynthesis: Carbon dioxide + Water + Light energy → Glucose +
Oxygen.
Flowers: These contain the reproductive organs and are often
brightly colored to attract pollinators like bees or butterflies.
3.Human System
Humans have several interconnected systems that perform specific
functions.
Skeletal System: Provides protection for soft organs (like the
skull for the brain), support for the body, and allows for
movement with the help of muscles. It's made of bones, connected
by joints that can be fused (like in the skull) or movable (like the
hip's ball-and-socket joint). Ligaments hold bones together, and
cartilage and synovial fluid reduce friction at joints.
Muscular System: Composed of muscles that contract and
expand to cause movement. Antagonistic muscle pairs (like the
biceps and triceps) work in opposition. Smooth muscle is found in
organs like the stomach, and cardiac muscle makes up the heart.
Circulatory System: The heart pumps blood through arteries
(carrying blood away from the heart) and veins (carrying blood
back to the heart). The system transports oxygen, nutrients, and
hormones throughout the body. Your pulse is a measure of your
heart rate.
Respiratory System: Facilitates the exchange of gases. Air enters
through the nose/mouth, travels down the trachea and bronchi,
and reaches the lungs. Here, oxygen enters the bloodstream, and
