1.3 Describe the common features shown by Prokaryotic Organisms such as Bacteria

1.3 Describe The Common Features Shown by Prokaryotic Organisms such as Bacteria.

Bacteria:

• Microscopic single-celled organisms;
• They have:
• a cell wall
• cell membrane
• cytoplasm
• plasmids
• They lack a nucleus but contain a circular chromosome of DNA
• Some bacteria can carry out photosynthesis but most feed off other living or dead organisms.
• e.g.
• Lactobacillus Bulgaricus - a rod-shaped bacterium used in the production of yoghurt from milk.
• Pneumococcus - a spherical bacterium that acts as the pathogen causing pneumonia.

1.2 Describe the Common Features Shown by Eukaryotic Organisms: Plants, Animals, Fungi & Protoctists

1.2 Describe the Common Features Shown by Eukaryotic Organisms: Plants, Animals, Fungi & Protoctists

Plants:

• Multicellular organisms.
• Cells contain chloroplasts and are able to carry out photosynthesis.
• Cells have cellulose cell walls & store carbohydrates as starch or glucose.

Animals:

• Multicellular organisms.
• Cells do not contain chloroplasts and are not able to carry out photosynthesis.
• Cells have no cell walls.
• They usually have nervous co-ordination and are able to move from one place to another.
• Often store carbohydrates as glycogen.
• e.g. mammals (humans) and insects (housefly and mosquito).

Fungi:

• Organisms that are unable to carry out photosynthesis.
• Body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei.
• Some examples are single-celled.
• Their cells have walls made of chitin.
• They feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products - this is known as saprotrophic nutrition.
• They may store carbohydrates as glycogen.
• e.g. Mucor:
• has the typical fungal hyphal structure, and yeast, which is single-celled.

Protoctists (protozoa):

• Microscopic single-celled organisms.
• Some like Amoeba (that live in pond water) have features like an animal cell.
• Others, like Chlorella have chloroplasts and are more like plants.
• A pathogenic example is Plasmodium, responsible for causing Malaria.

1.1 Understand How Living Organisms Share The Following Characteristics

1.1 Understand How Living Organisms Share The Following Characteristics:

I prefer to think of them as "MRS H GREN"

• M - Movement
• R - Respiration
• S - Sensitivity
• H - Homeostasis
• G - Growth
• R - Reproduction
• E - Excretion
• N - Nutrition

Movement:

• In all living cells structures in the cytoplasm move. In more complex organisms the whole structure may move.
• Animals may move their entire bodies, plants may move parts of their body in response to external stimuli such as light.

Respiration:

• This is a serious of reactions that take place in living cells to release energy from nutrients.
• This energy is used for chemical reactions that keep the body alive.

Sensitivity:

• Living organisms are able to detect and respond to changes in their external and internal conditions.

Homeostasis:

• This is the control of internal conditions to provide the best conditions inside cells for all the reactions needed for life to exist.

Growth:

• This is the permanent increase in size or dry mass (without water) of cells or the whole body of an organism.
• Your mass might change throughout the day as you eat and drink but your growth is the amount by which your body increases in size when you take nutrients into cells to increase their number and size.
• As organisms grow they may also change and develop.

Reproduction:

• Making and fertilisation of gametes to produce offspring.

Excretion:

• Living cells produce many products from the reactions that take place inside them.
• Some of these are waste products - materials that the body cannot use.
• e.g. Animals cannot use the carbon dioxide produced in respiration.
• Waste products may also be toxic so they must be removed from the body in excretion

Nutrition:

• The taking of nutrients such as organic substances and mineral ions into the body.
• Nutrients are the raw materials that cells need to release energy and to make more cells.

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