Question

1. Amoeba exhibit the characteristics of living things, that is, movement, irritability, nutrition, metabolism, growth, and reproduction. How many of these characteristics have you been able to observe? 2. Have you seen any evidence that the amoeba responds to a stimulus? 3. Is paramecium bilaterally symmetrical? Explain. 4. Why do you suppose paramecium has contractile vacuoles? 5. Did the cilia of paramecium beat in unison? Does this explain how the organism can move so uniformly through a fluid?

Answer 1

1. Movement- Amoebas appear under microscope like colorless or transparent jelly mvinf across the field very slowly as they change thier shape. When they change thier shape they can be seen as long protruding finger like projections. These are called pseudopods. They elongate and shorten as organism moves or engulfs the substrates given.

Nutrition- phagocytosis observed when amoeba engulfs the food by forming food vacuole. This can be observed and is called holozoic nutrition. The food is ingested, digested and egested.

growth and reproduction- binar fission a form of asexul reprudction is seen which produces daughter cells smaller than parents. The cell division can be seen. Two amoeba is formed from single parent and identity of parent is lost.

2. amoeba detects stimuli through changes in cell membrane. Light which is a threat to amoeba when shown they react by moving away from light. With the aid of pseudopodia they can move towards the stimuli,

3. Paramoecium is an asymmetrical animal due to the presence of oral groove which is an oblique depression running from apex of cell to middle of the body about the ventral surface. It has a well defined ventral and oral surface and has convex aboral and dorsal body surface. This stable asymmetrical pear shape gives them a stable upward orientation.

4. Paramoecium has complex contractile vacuoles which is surrounded by several canals which absorb water by osmosis from cytoplasm. It helps the cell to remove waste and excess water and is responsible for osmoregulation in these single celled organisms.

5. In order for this organism to move forward the cilia beat in an angle backwards in unison. And they moves by spiraling through water through an invisible axis in the pursuit of food. And they have chemical sensors which which enable them to locate food souces.