Ch 2. The Characteristics of Life

1.2.2 Definition of Life

Need to know Define the term ‘Life’ Define the terms – Metabolism & Continuity of life List the 5 "characteristics of life", Define nutrition, excretion, response and reproduction.

Life involves the interaction of the characteristics of life.

What makes Plants & Animals ‘living’? Do they have common features? Do they have common behaviours?

Common Characteristics Living things: are highly organised are composed of tiny units called cells grow excrete move react to their surroundings feed reproduce

Metabolism METABOLISM Metabolism refers to the chemical reactions that occur in the cells of organisms. These reactions are responsible for the process of Growth Repair Responsiveness Reproduction

Continuity of Life Continuity of life is the ability of an organism to exist from one generation to the next. You need reproduction and heredity to achieve continuity. Genes are hereditary factors that are passed on from one generation to the next during reproduction.

Learning check Explain the term Metabolism. Metabolism refers to the chemical reactions that occur in the cells of organisms. Explain the term ‘Continuity of Life’. Continuity of life is the ability of an organism to exist from one generation to the next.

How do we know if something is alive? It has organization – cells, tissues, organs, etc. It uses energy Grows and develops Excretes Reproduces Responds to the environment Adapts to the environment

Organisation The Cell is the basic unit of all living organisms Specialized structures Unicellular or multicellular If cell structure is damaged its function is also affected

Levels of organisation Cell Tissue Organ Organ system Organism Population Community Ecosystem Biosphere

The Cell: High School Biology This animation shows the structure and function of plant and animal cells for high school biology, including organelles like the nucleus, nucleolus, DNA (chromosomes), ribosomes, mitochondria, etc. Also included are ATP molecules, cytoskeleton, cytoplasm, microtubules, proteins, chloroplasts, chlorophyll, cell walls, cell membrane, cilia, flagellae, etc. 7.21mins

Energy All energy for living things can be traced back to the sun (primary source of energy) Organisms use light energy to see (vision), to make food (plants use sunlight during photosynthesis), for warmth (organisms eat the plants to get energy during respiration

ENERGY FLOW

PHOTOSYNTHESIS

Learning check It has organization – cells, tissues, organs, etc. How do we know something is alive? It has organization – cells, tissues, organs, etc. It uses energy Grows and develops Excretes 5. Reproduces 6. Responds to the environment 7. Adapts to the environment

Growth and Development Growth – increase in size Development – change in form or shape Amount of growth varies in different organisms Nutrition maintains the organisation and growth of living organisms

Nutrition This is the process involved in the intake and use of energy and materials from the environment.

Sources of Nutrition In Plants: Autotrophs - make food by photosynthesis and absorbing chemicals from the environment . In Animals: Heterotrophs - feed on other organisms Energy flow: Sun  Plants Animals

Excretion Excretion - is the removal of wastes made in the body cells e.g. Urea, carbon dioxide and water. All living things must get rid of waste material – if it was allowed to accumulate it would become toxic to the organism A balance must be maintained between their internal and external environments

Methods of excretion Various organised structures involved In Animals: the urinary system, skin, lungs In Plants: the stomata

Learning check 1. What is meant by nutrition? This is the process involved in the intake and use of energy and materials from the environment. 2. What is meant by Excretion? Excretion - is the removal of wastes made in the body cells e.g. Urea, carbon dioxide and water.

Response and Adaptation Response is the ability of an organism to react to changes both inside and outside their bodies. Adaptation – plants and animals change in response to long-term changes in the environment; these may be passed on to future generations (Charles Darwin)

Methods of response In Animals: organised structures respond to light, sound, touch, etc. In Plants: growth towards or away from a stimulus e.g. light, water, fertilisers, etc.

Reproduction Reproduction is the ability of an organism to produce new individuals of its own kind. Life comes from life. Necessary for the survival of the species Offspring can be genetically the same as or different from parent(s).

Methods of reproduction Asexual: involves only one parent e.g. in bacteria and protista divide from one cell into two - binary fission. During mitosis one cell divides into two e.g. in plants and animals. Sexual: involves two parents and the production of male and female gametes e.g. in plants and animals.

Learning check What is meant by response? Response is the ability of an organism to react to changes both inside and outside their bodies. What is meant by reproduction? Reproduction is the ability of an organism to produce new individuals of its own kind. 3. Name the methods of reproduction and explain. Asexual: involves only one parent . Sexual: involves two parents and the production of male and female gametes.

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