The Eye
What part of the eye controls how much light enters by changing the size of the pupil?
Iris
What is the basic cell type that carries electrical signals in the nervous system?
Neuron
What are chemical messengers released by glands into the bloodstream called?
Hormones
What nutrient group gives the body the most concentrated energy (calories per gram)?
Fats (lipids) provide about 9 calories per gram vs. 44 calories per gram for carbohydrates and proteins
Name the transparent structure that focuses light onto the retina.
Lens
Name the two main divisions of the nervous system and give one component of each.
Central Nervous System (brain and spinal cord); Peripheral Nervous System (nerves branching to body)
Which gland is often called the "master gland" because it controls many other endocrine glands?
Pituitary gland
Why are fruits and vegetables important in a healthy diet? Give two reasons.
Provide vitamins and minerals, supply fiber for digestion, and help prevent disease (supports immune health, reduces constipation
What is the light-sensitive layer at the back of the eye that contains photoreceptor cells called?
Retina
What is this pathway called?
Sensory receptor → sensory neuron → spinal cord interneuron → motor neuron → effector
Reflex arc
What response does adrenaline cause?
"Fight-or-flight" response.
Define "protein" in terms of function in the body.
It's the substance that provides the nutrients needed to build up our own body structures and to replace worn and damaged tissues.
Identify the two types of photoreceptor cells and give one key difference between them.
Rods (more light-sensitive, for low-light and peripheral vision) and Cones (color vision, detail in bright light)
Describe how a nerve impulse travels across a synapse (mention neurotransmitter role).
Neurotransmitters released from the axon terminal cross the synaptic gap and bind to receptors on the next cell, triggering a new impulse
Give one hormone produced by the pancreas and describe its role in blood sugar regulation.
Insulin (lowers blood glucose by helping cells take in glucose); glucagon (raises blood glucose)
Explain the difference between sugars and starches and provide one food example of each.
Sugars are simple carbohydrates such as fruits and starches are complex carbohydrates like cereals and potatoes.
Explain how the eye adjusts to focus on near objects (give the name of the process and what the lens does).
Accommodation: the ciliary muscles contract, causing the lens to become thicker/more rounded to focus on near objects
Explain the difference between voluntary and involuntary actions and give one example of each.
Voluntary actions are controlled consciously (e.g., raising your hand); involuntary actions are automatic (e.g., heartbeat, digestion)
Compare the speed and duration of responses from the nervous system versus the endocrine system.
Nervous system: fast, short-lived responses (milliseconds to seconds). Endocrine system: slower, longer-lasting responses (minutes to hours or longer)
Describe three dietary changes someone could make to reduce the risk of heart disease (short, evidence-based suggestions appropriate for 8th grade).
Examples: reduce intake of saturated and trans fats; increase fruits, vegetables, and whole grains; choose lean protein and limit added sugars and salt