12C Flashcards
- What does bilateral symmetry mean?
There are two equal sides to the animal. They are mirror images.
- What does free living mean?
The worm does not depend on another organism for survival
What type of symmetry does a planarian have?
Bilateral symmetry
- Hoe many possible planes are there to divide a bilateral planarian?
One
- Give an example of a flatworms?
Planarian
- Which phylum do flatworms belong to?
Platyhelminthes
- Some flatworms are free living. What does this mean?
They do not depend on other organisms for survival
- Are most flatworms parasitic?
Yes
What does parasitic mean?
They live in other organisms called hosts and get their nourishment from the hosts
- Name three parts of the planarians nervous system
2 longitudinal nerves that run down the sides of the body. There are ganglions at the top of each longitudinal nerve that control the planarians responses to stimuli. Transverse nerves connect the longitudinal nerves
- What is the name for an invertebrates response center?
Ganglion also know as a simple brain
What are four major stimuli that plantains respond to?
Light, chemicals, touch, water
What is a stimulus?
Something that causes a reaction to an organism
Explain the planarian responses of the nervous system…
Nerve cells receive the stimulus. They convert the stimulus to impulses which travel along the nerves to the ganglion. The ganglion receives the impulses and then sends other impulses to various structures of the planarian causing it to respond.
How many eyespots does the planarian have?
Two
Does light cause a positive or negative response to light?
Negative they move away from light for protection
What reaction helps planarians find food?
Their response to chemical stimuli
How do planarian reproduce?
Asexually by regeneration.
Sexually due to being hermaphroditic
What does hermaphroditic mean?
They have both male and female organs in one body
What does reproducing asexually by regeneration mean?
That’s the planarian is split into pieces each piece will regrow to form a new adult planarian
How do planarians get rid of liquid waste products?
Through a system of tiny tubes. At the end of each tube are structures called flame cells which have tiny cilia that move water and waste through the tubes to tiny holes called excretory pores where waste is excreted from the planarian.
How does a planarian breathe?
The planarians body is very thin which allows the animals cells to exchange oxygen and carbon dioxide directly with the environment.
Explain the digestion of the planarian
The planarian extends a long muscular tube, called the pharynx through the mouth and sucks food into the intestine which extends to every area. Of the planarians body. Enzymes secreted by cells in the intestine start digesting the food. The cells then absorb the pieces of food and then finish digesting them. Indigestible material is pushed out of the intestine through the mouth.
Give an example of a roundworm?
Ascaris
