Biology Topic 1

2. - Loops of DNA found in the cytoplasm of prokaryotic cells.
3. - Pathogenic protoctists that cause malaria.
5. - Long filaments of a fungus that contain many nuclei.
6. - Microorganisms that cause infectious disease.
7. - The basic building block of all living organisms.
11. - A type of cell found in plants and animals that contains a nucleus.
13. (TV) - A widespread plant pathogen affecting many species of plants which produces a mosaic pattern on the leaves. It infects chloroplasts and limits plant growth.
14. - A single-celled fungus.
15. - A spherical, pathogenic bacterium that causes pneumonia.
16. - An outer, structural layer that surrounds some cells. In plant cells, it is made of cellulose. In fungi, it is made of chitin.
17. - A multicellular fungus that has a hyphal structure.
18. - A partially permeable barrier that surrounds the cell.
19. - A double-stranded polymer wound to form a double helix. It carries the genetic code.
21. - An infection virus that causes influenza (the flu).
22. - An organelle which is the site of photosynthesis.
23. - Microscopic single-celled organisms.

1. - The mode of extracellular nutrition in which digestive enzymes are secreted onto the food outside the cell and the products of digestion are absorbed.
2. - An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.
4. - A collection of thread-like hyphae in a fungus.
8. - A non-living organism that can only reproduce inside host cells. Viruses have no cells, but possess a protein coat containing nucleic acids (DNA or RNA).
9. - A rod-shaped species of bacterium used to produce yoghurt from milk.
10. - A type of cell found in bacteria that does not contain a nucleus.
12. (HIV) - An infectious virus that weakens the immune system and can lead to AIDS (acquired immunodeficiency syndrome).
16. - A protoctist that has features similar to plant cells e.g. chloroplasts.
20. - Protoctists that live in pond water and resemble animal cells.