Protists/Protozoans

Question 1

What is endosymbiosis and what is the evidence of it?

Answer 1

A process in which prokaryotic cells engulfed but did not digest another, the engulfed cell becoming an organelle inside the host cell. Cell mitochondria and chloroplasts possess their own DNA, RNA, and ribosomes.

Question 2

What are the different locomotry structures used by protozoans?

Answer 2

Cilia and flagella- Projections form the cell. Each contains 9 pairs of microtubules arranged in a circle around a central pair- a 9+2 arrangement that is conserved for all cilia and flagella throughout the animal kingdom.

Pseudopodia- Extensions of the cell cytoplasm (fake foot)

Question 3

How do protozoans excrete metabolic wastes?

Answer 3

This process occurs through diffusion throughout the entire body’s surface. In fresh water protists, some soluble wastes are expelled with the out-flowing water.

Question 4

What are the pros and cons of asexual and sexual reproduction?

Answer 4

Asexual advantages:

1. Requires less energy
2. No need for a mate
3. Very little environmental constraint
4. Rapidly reproduces in a suitable habitat

Asexual disadvantages:

1. Little to no genetic diversity
2. There is less variation produced with the offspring.
3. Asexual reproduction usually leads to struggle for existence as well as overcrowding.

Sexual advantages:
-Large chance of new organisms being created
Species would better be able to adapt

Sexual disadvantages:
only half the population
(females) is capable of gestation.
two parents have to be involved in the
process.
having to find a mate and producing gamete cells
Fertilization has to take place and there is no guarantee that the nucleus of the male sex cell would fuse with the female sex cell.

Question 5

What is encystment and why/when should a protozoan undergo it? Which kinds of protozoans are more likely to show encystment?

Answer 5

The process of creating dormant forms surrounded by a resistant outer covering. Protozoans will engage in this process in order to survive in harsh conditions. Parasites can also do it when transitioning between hosts.Examples: entamoeba, giardia

Question 6

Can you name the protozoans that cause different human diseases?

Answer 6

Giardia (giardiasis), Trichomonas (Trichomoniasis), Trypanosoma (African sleeping sickness), Entamoeba (dysentery), Plasmodium (malaria)

Question 7

Which produce huge red tides?

Answer 7

Gymnodinium

Question 8

Which produce huge lime deposits?

Answer 8

Foraminiferans, Radiolarians

Question 9

What are the two defining characteristics of protozoans?

Answer 9

1. Eukaryotic

2. Unicellular