The nature and variety of living organisms

Question 1

What are the main characteristics shared by all living organisms?A: All living organisms share the following characteristics:

Answer 1

Nutrition: They need nutrients to provide energy and materials for growth and repair.

Respiration: They release energy from food.

Excretion: They remove metabolic waste from their bodies.

Sensitivity: They respond to changes in their environment.

Movement: They can move and change position.

Homeostasis: They regulate internal conditions like temperature and water levels.

Reproduction: They produce offspring to continue the species.

Growth and Development: They grow and develop into mature organisms

Question 2

eukaryotic organisms

Answer 2

plants, animals, fungi, protoctists

Question 3

What are the common features of eukaryotic organisms (plants,

Answer 3

Plants: Multicellular, contain chloroplasts for photosynthesis, have cellulose cell walls, and store carbohydrates as starch. Example: Maize (cereal), Peas (legume).

Question 4

What are the common features of eukaryotic organisms: animals

Answer 4

Animals: Multicellular, lack chloroplasts and cell walls, have nervous coordination, and store carbohydrates as glycogen. Example: Humans (mammal), Mosquito (insect).

Question 5

What are the common features of eukaryotic organisms: fungi

Answer 5

Fungi: Cannot photosynthesize, body is made of mycelium with hyphae containing multiple nuclei, have chitin cell walls, and feed by saprotrophic nutrition. Example: Mucor (hyphal), Yeast (single-celled).

Question 6

What are the common features of eukaryotic organisms: protoctists

Answer 6

Protoctists: Single-celled and microscopic, some are plant-like (Chlorella), some are animal-like (Amoeba), and some are pathogenic (Plasmodium - causes malaria)

Question 7

: What are the common features of prokaryotic organisms such as bacteria?

Answer 7

Bacteria are single-celled with the following features:

Cell wall, cell membrane, cytoplasm, and plasmids

Circular DNA (no nucleus)

Some can photosynthesize, but most feed off other living or dead organismsExamples: Lactobacillus bulgaricus (used in yogurt production), Pneumococcus (causes pneumonia)

Question 8

What is a pathogen and what types of organisms can be pathogens?A:

Answer 8

A pathogen is an organism that causes disease. Pathogens include:

Fungi: Example: Athlete’s foot fungus

Bacteria: Example: Pneumococcus (causes pneumonia)

Protoctists: Example: Plasmodium (causes malaria)

Viruses: Example: HIV (causes AIDS), Influenza virus (causes flu)

Question 9

What are the characteristics of viruses and why are they not classified as living organisms?:

Answer 9

Viruses are not considered living because they cannot reproduce without a host cell. They are small particles with:

Protein coat surrounding DNA or RNA

No cellular structure

Infect all types of living organismsExamples: Tobacco mosaic virus (damages chloroplasts), Influenza virus, HIV