The Simplest Life Forms 2.0

unit 7

The Simplest Life Forms

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Archaeobacteria

fungi

eubacteria

virus

protoctist

Protoctists

Main Characteristics

This Kingdom includes a group of eukaryotic organisms with no specific tissue structure.

They can be unicellular or multicellular.

Two groups: - Algae: autotrophic protoctists - Protozoans: heterotrophic protoctists

Algae

Algae are aquatic eukaryotic autotrophs organisms. They perform photosynthesis. They appear in various shapes and sizes (from microscopic algae to giant seaweeds).

• Algae can be unicellular or multicellular. Some species of unicellular algae form colonies.

• Algae cells have a cell wall. Algae cells don´t form tissue or organs.

• Algae don´t have true stems, leaves or roots.

• Algae live in fresh and seawater aquatic enviroments.
• Some spend their life floating (Planktonic) and others are attached to the bottom (Benthic)

Vital Functions of Algae

Nutrition

Reproduction

Interaction

Algae reproduce sexually (with male and female gametes), asexually or in both ways.

Unicellular algae move using flagella. Multicellular algae can´t move on their own.

Algae perform photosynthesis, so algae have chlorophyll.

Asexual reproduction

• Binary fission

• Spores

• Fragmentation

Some planktonic algae produce light by bioluminiscence.

Chlorophyll is green. But also algae have other pigments of different colours (from red to brown).

Classifying Algae

They are green because of chlorophyll. This algae live in all types of aquatic environment. Green algae store starch (reserve substance).

GREEN ALGAE

They are brown because of brownish-green pigments. Most are multicellular and live in marine habitats."

BROWN ALGAE

They have reddish pigments which allow them to perfom photosynthesis in deeper water better tha green or brown algae. They can live in dephts of about 100m.

RED ALGAE

Importance of Algae

IN ECOSISTEMS

IN FOOD PRODUCTION AND INDUSTRY

• Green algae are a source of carotene (use as a food colouring).
• Red algae cointain agar, a jelly-like substance used as a thickener in food.
• Other red algae contain carrageenan used for gelatine capsules and in some cheeses.
• Some species of algae are used as food because they are rich in vitamines, fibre and proteins.

• Algae are the most common producers in aquatic ecosystems.

• They start aquatic food chains, feed aquatic herbivores and produce oygen.

HARMUL ALGAE

• Some types of planktonic algae (Noctiluca scintillans) produce harmful tides when they reproduce in a massive way.

• Red tides produce potent natural toxins threaten wildlife, human health, marine ecosistems and fisheries.

Homework

Do a research about DIATOMS and their importance in industry.

Find out about the uses and benefits of edible seaweeds. Which are the most common edible seaweeds? In which countries are they usually consumed as a part of the diet?

Look for information about the Sargasso Sea. Write a short report including its location and the type of algae found there. Why is known as the "floating desert"?

Protozoans

• Protozoans are unicellular, eukaryotic, heterotrophic organisms.

• Some protozoans are free-living and live in the soil and in fresh or salt water.

• Some protozoans are parasites.

• Protozoan cells do not have cell wall and never form tissues.

Vital Functions of Protozoans

Reproduction

Nutrition

Interaction

Protozoans are heterotrophs and eat bacteria, algae or other protozoans to obtein nutrients.

Most protozoans reproduce asexually (binary fission or multiple fission.

Some protozoans are immobile while others move using cilia, flagella or pseudopods (false feet).

The nutrition process is called phagocytosis. A portion of the cell membrane surround a food particle and engulf it.

Some reproduce sexually or a combination of sexual and asexual reproduction.

Classifying Protozoans

(according to the way they move)

FLAGELLATES

CILIATES

• Ciliates have cilia at some point in their life cycle.

• They can be parasites or free-living.

• There are also symbiotic ciliates that live in the stomachs o rumiant animals (cow) and help them in digestion.

• Flagellates move using flagella.

• Some are free-living and some are parasites that ive in humans and other animals.

• Trypanosoma brucei is a parasite that causees sleeping sickness. It is transmitted by the tsetse fly.

RHIZOPODS

SPOROZOANS

• They are parasitic and inmobile.

• Plasmodium falciparum causes malaria, which is transmitted by the Anopheles mosquito.

• Amoebas: they don´t have a shell. They are usually free-living and also include parasites. They move by changing the shape of their body, forming pseudopods.

• Foraminifera: they are marine organisms with a calcium carbonate shell.

Importance of Protozoans

In ecosystems. Free-ling protozoans are important as primary or secondary consumers (in soil and aquatic ecosystems). They control the population of soil bacteria by feeding on them. They also increase soil fertility.

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Protozoans have an important role in wastewater treatment processes. They break down organic waste substances in the water.

The skeletal deposits of dead marine protozoans become fossilised and were converted into sedimentary rocks.

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Harmful protozoans. Some protozoans are harmless, however other s can cause serious diseases (sleeping sickness, amoebic disentery, malaria, Chagas´disease, etc).

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Fungi

The Fungus Kingdom includes eukaryotic heterotrophic organisms.

• They can be unicellular (YEASTS) or multicellular (MOULDS and MUSHROOMS).

Vital Functions of Fungi

NUTRITION

All fungi are heterotrophic:

• Saprophytic Fungi: they feed on decomposing organic matter from other living things.

• Parasitic fungi cause diseases in plants and animals.

• Symbiotic fungi establish relationships with other organisms. Lichens are organisms formed between a fungus and an alga. The fungus provides moisture and mineral salts, the alga provides food through photosynthesis. Mycorrhiza is an association between a fungus and a plant. The fungus provides moisture and mineral salts, the alga provides food through photosynthesis.

Vital Functions of Fungi

REPRODUCTION

Gemmation

• Fungi reproduce asexually by spores or gemmation. Spores are produced on special cells underside of the cap.

• Some fungi reproduce sexually.

INTERACTION

• Fungi are immobile