Define and Relate
Isolecithal/Holoblastic
Isolecithal: eggs with evenly distributed, small yolk.
Holoblastic: complete cleavage of the entire egg.
Relation: Isolecithal eggs undergo holoblastic cleavage because the yolk does not impede division.
You see tightly packed cells with almost no ECM. What tissue type is it?
Epithelial tissue.
What ion binds to troponin to start muscle contraction?
Calcium (Ca²⁺)
How does gastric bypass reduce food intake?
It creates a very small stomach pouch.
Why do gills require water flow to function effectively?
Water must move across gill surfaces to deliver oxygen and remove CO₂.
Blastocoel/Coelom
Blastocoel: fluid-filled cavity inside the blastula.
Coelom: body cavity lined with mesoderm.
Relation: Both are cavities, but the blastocoel forms early, while the coelom forms later in development.
You see scattered cells in a matrix with visible fibers. What type of tissue is it?
Connective tissue.
What protein moves aside to expose myosin‑binding sites on actin?
Tropomyosin
Which two regions are bypassed in gastric bypass, reducing nutrient absorption?
The stomach and duodenum.
What structural features increase the surface area of gills?
Gill filaments and lamellae greatly increase surface area.
Mesoderm/Coelom
Mesoderm: middle germ layer forming muscle, bone, connective tissue.
Coelom: mesoderm-lined body cavity.
Relation: The coelom is formed from mesoderm.
Skeletal tissue?
What is the name of the step where the myosin head pivots and pulls actin toward the center of the sarcomere?
The power stroke
Why does dumping syndrome discourage overeating?
Food enters the small intestine too quickly, causing discomfort.
How do lungs increase gas‑exchange efficiency compared to simple sacs?
Lungs have internal branching and alveoli that increase surface area.
Entercoely/Schizocoely
Enterocoely: coelom forms by gut outpocketing (deuterostomes).
Schizocoely: coelom forms by splitting mesoderm (protostomes).
Relation: Both describe coelom formation, but via different mechanisms.
Nervous tissue.
What molecule must bind to myosin to release it from actin?
ATP.
Why can’t animals digest cellulose on their own?
They do not produce cellulase.
Why is countercurrent exchange beneficial in aquatic respiration?
It maintains a gradient that maximizes oxygen uptake along the entire gill surface.
Triploblastic/Coelom
Triploblastic: animals with three germ layers.
Coelom: mesoderm-lined body cavity.
Relation: Only triploblastic animals can form a coelom because mesoderm is required.
You see branching striated fibers with intercalated discs. what tissue type is it?
Cardiac tissue.
During contraction, how do the filaments cause the sarcomere to shorten?
They slide past each other (thin filaments pulled toward the M‑line)
Where do ruminants house microorganisms that digest cellulose?
The rumen and reticulum.
How do tracheal tubes deliver oxygen directly to tissues without blood involvement?
Air travels through branching tubes that reach every cell, bypassing circulation.