Pertanyaan dan pembahasan biologi


Protista

1. Perbedaan mendasar apa yang membedakan protozoa berbeda dengan alga?

  • The basic difference between protozoans and algae is the fact that protozoans are heterotrophs while algae are photosynthetic autotrophs.

2. Karakteristik protozoa manakah yang menyebabkan mereka digolongkan ke dalam kelompok yang menyerupai hewan?

  • they are heterotrophs,
  • they have a rudimentary locomotion system (amoeboid movements, cilia, flagella),
  •  they do not have cell wall,
  • some species present structures that resemble structures of a primitive digestive system, with cytostome (mouth) and cytopyge (anus), specialized in digestion and excretion.

3. Sebutkan struktur dasar dari sel protozoa?

  • Protozoans are eukaryotic cells so they have organelles and structures common to this kind of cell:
  • endoplasmic reticula,
  • Golgi apparatus,
  • digestive vesicles,
  • ribosomes,
  • mitochondria,
  • nucleus with genetic material, karyotheca, etc. All these elements are found dispersed throughout the cytoplasm.
  • Protozoans do not have cell walls.
  • Protozoans from the mastigophora group (like trichomonas) have flagella and others, others from the ciliated group (like paramecium) have cilia.

 4. Apakah protozoa mempunyai nukleus?

  • Yes

5. Apakah fungsi utama makronukleus dan mikronuklues pada Paramaecium sp.?

  • The macronucleus is properly the cell nucleus,
    •  it has DNA and RNA and acts as the center of the cellular control and regulation.
  • The micronucleus has reproductive functions and it is related to the conjugation process (sexual reproduction).

6. Bagaimana Amoeba, Paramaecium dan Trichomonas bergerak?

  • Amoebae move by amoeboid movements, small projections and invaginations of their plasma membrane (pseudopods) that alter the external morphology of the cell making it move on surfaces.
  • Paramecia have the outer face of their plasma membrane covered by cilia that flap helping the cell to move.
  • Trichomonas are flagellated protozoans, i.e., they have relatively long filaments outside the cell that beat and make possible active swimming in fluid environments.

 7. Apakah fungsi vakuola kontraktil pada protozoa?

  • The vacuoles of protozoans are internal structures specialized in water storage that when necessary liberate water to the cytoplasm. Vacuoles thus can dilute the cytoplasm for it to enter into osmotic equilibrium with the environment. Protozoans of fresh water then need vacuoles more since their intracellular is hypertonic in relation to the exterior. Without the dilution mechanism provided by the vacuoles, protozoans of fresh water would absorb too much water and would die.

8. Bagaimanakah secara umum protozoa berkembang biak, jelaskan?

  • The most frequent form of asexual reproduction is binary division, or scissiparity, in which the cell divides itself by mitosis originating two daughter cells.

 

  • Some species, like the plasmodium, agent of malaria, reproduce asexually by schizogony (multiple fission); in this form of reproduction the cell becomes multinucleated, generally inside a host cell, and each nucleus is expelled out together with cytoplasm portions giving rise to new protozoans.

 

  • The sexual reproduction in protozoans can happen by conjugation, with incorporation of genetic material from one cell into another, or by gametes that fecundate others and form zygotes. In the plasmodium sexual reproduction happens in the mosquito, the definitive host, and the zygote undergoes mitosis (sporogony) creating many sporozoites.

9. Sebutkan 4 kelompok protozoa!

  • The four main groups of protozoans are the sarcodines (that form pseudopods, like amoebae), the mastigophores (flagellated, like the trypanosome that causes Chagas’ disease), the ciliated (like paramecia) and the sporozoans (spore-forming, like plasmodia).

10. Apakah algae bereproduksi secara seksual atau aseksual, bagaimana caranya?

  • There are algae that reproduce sexually and there are algae that reproduce asexually.
    • In unicellular algae reproduction is generally asexual by binary division
    • In pluricellular algae asexual reproduction can occur by fragmentation or by sporulation.

 

  • In sexual reproduction of algae, uni or pluricellular, there is fusion of gametes (syngamy). There are algae in which all cells can become gametes and there are algae in which only some cells can play that role. Some species may present alternation of generations, forming gametophytes and sporophytes with different ploidies.

11. Apakah manfaat komersial dari algae?

  • Many algae have high nutritional value and are commercialized and consumed as human food, they are very popular food in the oriental world. Jelly compounds are extracted from some algae, like glues and pastes for industrial and commercial use.
  • The agar-agar, used as a medium for biological culture in laboratories and in medicines, and the substance known as carrageenin, a component of tooth pastes, cosmetics, paint and hygienic products, are extracted from rhodophyte algae. Diatom algae deposited on the bottom of the sea form diatomites, used in the production of filters, refractories, thermal isolation and cement. Some algae are used as agricultural fertilizers.

12. Apakah yang dimaksud dengan fenomena “Red Tide”?

  • Red tide is a phenomenon that occurs when dinoflagellates (algae from the pyrrophyte group) proliferate excessively in the ocean. These algae liberate toxins that affect the nervous system and can cause death when ingested by marine animals and by humans that eat contaminated animals.

kelas XII

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