Muscles in Action
When you lift a heavy book, this muscle at the front of your arm contracts and gets shorter.
bicep
Muscles can only move bones by exerting this direction of force on them, they can only __________.
pull
Animals that have a backbone inside their body are called _____________.
vertebrates
Substances taken into the body to cure illness, relieve pain, or prevent disease are called __________.
Medicines
Scientists use this decision-tree tool with simple questions to sort and identify living things.
identification key
To lower your arm back down after bending it, this muscle at the back of your upper arm contracts.
tricep
In a working model of an arm, these objects are used to represent muscles pulling on card "bones".
rubber bands
Crabs, beetles, and locusts are protected by a hard, shell on the outside of their bodies called __________.
exoskeleton
Before taking any medicine, children should always __________________.
ask an adult (or check with an adult)
Questions at every step in a standard identification key must be answered with _________ and _______.
"Yes" and "No"
Because one muscle contracts while the other relaxes to produce movement, muscles are described as working in ________.
pairs
Regular movement and exercise help keep us healthy by making our ___________ and __________ work better.
heart and lungs
Lizards, snakes, and tortoises are land-dwelling vertebrates covered with dry scales and are called _________________.
reptiles
People with asthma or breathing difficulties deliver medicine directly into their lungs using _________.
inhaler
In a vertebrate key, answering "Yes" to "Does it have feathers?" leads directly to this group.
birds
When a muscle contracts to pull on a bone, it gets shorter and gets ___________.
Thicker (bigger)
To make your muscles grow bigger and stronger over time, you must _______________ regularly.
exercise
Spiders belong to an invertebrate group that has an exoskeleton and this total number of legs.
8
Illnesses caused by germs that can spread from one living thing to another are called ___________ disease.
infectious
An invertebrate key that asks "Does it have 6 legs?" and "Does it have wings?" would identify a bee as an __________.
insect
Unlike skeletal muscles, this organ is a special muscle that is not joined to any bones.
heart
Doing this for long periods without moving is not good for your physical health.
sitting still
Birds are vertebrates covered with feathers whose front limbs are called _____________.
Wings
In addition to human beings, animals and __________ can also get infectious diseases.
plants
If an identification key for soft-bodied land animals asks "Does it have a shell?", answering "Yes" leads to this creature.
snail