Match these items. 1. organisms in which a parasite lives virion 2. microorganisms commonly found living in or on a human host 3. area of prokaryotic cell that is dense with genetic material phycology 4. structure of an alga viroid 5. pathogenic abnormal protein structure normal flora 6. without free oxygen pathogen 7. rupturing of a cell salinity 8. concentration of salt in water virologist 9. organism which causes disease prion 10. obtain food from dead organic material lysis 11. pathogenic rna molecule saprophyte 12. mutually positive relationship anaerobic 13. organism which lives in or on another organism nucleoid 14. the study of algae symbiosis 15. scientist who studies viruses thallus 16. single virus unit parasite

1. Organisms in which a parasite lives; Host. Hosts are organisms that harbors a parasitic, a mutual, or a commensal, symbiont, providing nourishment and shelter. Examples, animals playing host to parasitic worms, cells harboring parasitic viruses, legumes hosting mutualistic nitrogen fixing bacteria.

2. Microorganisms commonly found living in or on a human; parasite. Parasite is an organism that lives on or in another organism (hosts) and gets food or nourishment from or at the expense of the host. They are known to cause diseases in humans, with some infections being easily treated and others are not. 

3. Area of prokaryotic cell that is dense with genetic material; Nucleoid.  Nucleoid is an irregular shaped region within the cell of a prokaryote which contains all or most genetic materials called the genophore. Unlike the eukaryotic cells in prokaryotes the nucleoid is not surrounded by a nuclear membrane.

4. Structure of an alga; thallus. Thallus is a plant body in algae, fungi, and other lower organisms. it is composed of filaments or plates of cells and ranges in size from a unicellular structure to a complex tree like form. The body of an algae is always a thallus which is not differentiated in to root, stem and leaves.

5. Pathogenic abnormal protein structure; Prion. Prions are infectious agents that are composed of a protein material that can fold in multiple, structurally abstract ways. These folding may be transmissible to other prions proteins, leading to a disease in a manner similar to the spread of viral infection.

6. Without free oxygen; anaerobic. Anaerobic refers to the existence, living or occurring in absence of oxygen. For example anaerobic respiration is a type of respiration that takes place in absence of oxygen to produce alcohol and energy. It is a very important process in the brewing and baking industries.

7. Rupturing of a cell; lysis . Lysis is the breaking down of the cell membrane thus causing rupturing of the cell, this may be due to viral, enzymatic, or osmotic mechanisms that comprise its integrity. For example; Haemolysis (bursting of red blood cells in hypertonic solution.

8. Concentration of salt in water; salinity. Salinity is the measure of all salts dissolved in water. It is usually measured in parts per thousands. For example salinity of sea water may be determined by measuring the amount of dissolved salts mainly sodium and chloride. 

9. Organism which causes disease; pathogens. Pathogens or infectious agents are microscopic microorganisms that cause or have a potential to cause a disease or illness. They include; bacteria, viruses, protists (such as amoeba, plasmodium among others), fungi, parasitic worms and prions.   

10. Obtain food from dead organic material; saprophyte. Saprophytes are organisms that survives by consuming of feeding on nutrients from dead and decaying plants or animals materials, that is, organic matter. They include fungi, molds, most bacteria, actinomycetes, and some few plants and animals. 

11. Pathogenic RNA molecule; Viroid. Viroid is an infectious RNA molecule which is similar to a virus but not exactly similar. It is smaller than a virus and lacks caspid. It is a coiled naked RNA molecule that can affect a cell. The RNA is single stranded unlike DNA ,however in viroids and coils around itself to become double stranded for strength.

12. Mutually positive relationship: symbiosis. Symbiosis is a relationship in which two or more organisms live closely together which may benefit each of the organisms involved. Symbiosis may be Commensalism, mutualism, or even parasitism. Example is the relationship between cattle egrets and cattle, which is a type of commensalism. 

13. Organism which lives in or another organism; normal flora. Normal flora are bacteria which are found living in other living organisms (human or animals) or inanimate object without causing a disease. In human bodies they are found on a semi-permanent basis without causing diseases. 

14. The study of algae; phycology. Phycology is a branch of study dealing with taxonomy, cell biology, and ecology of algae. Algae are mainly autotrophic non-vascular organisms mainly classified into plants, protozoa and Chromista. They comprise several groups of plant like organisms, some of which are regarded as members of kingdom plantae. 

15. scientist who studies viruses;virologist. Virology is the study of viruses and virus like agents including their taxonomy, disease-producing property, cultivation and their genetics. Virologists study viruses that affect humans, animals , insects, bacteria, fungi, and plants in a community, agriculture, clinical and natural environments.

16. Single virus unit; virion. Virion is the entire virus particle, consisting of an outer protein shell called the caspid and an outer inner core of nucleic acid which is either a DNA or an RNA. The core confers infectivity by the virus while the caspid provides specificity to the virus.