Question

1.2 list several features of planaria that suggest adaptation to a free - living lifestyle.
1.3 why do you suppose the pharynx is centrally located on the body, as opposed to being located at the anterior end of the animal?
1.4 why is the gastrovascular cavity so extensively branched?
1.5 flatworms were the first organisms to evolve specialized cells for excretion (flame cells). what specific purpose does an excretory system serve?

Explanation:

1.2 Planaria have eyespots for light - detection, cilia for locomotion on surfaces, and a simple brain for basic sensory - motor coordination, all of which are adaptations for free - living.
1.3 A centrally located pharynx allows for feeding from multiple directions without the need to re - orient the entire body, which is efficient for a free - moving organism.
1.4 The extensive branching of the gastrovascular cavity increases the surface area for digestion and nutrient absorption, which is beneficial for a free - living organism with variable food sources.
1.5 The excretory system with flame cells in flatworms serves to remove metabolic waste products, maintain osmotic balance, and keep the internal environment stable for the organism's survival.

Answer:

1.2 Eyespots for light detection, cilia for locomotion, simple brain for coordination.
1.3 Allows feeding from multiple directions efficiently.
1.4 Increases surface area for digestion and absorption.
1.5 Removes waste, maintains osmotic balance, stabilizes internal environment.