What Is Life?

Chapter 3

What does life include the capacity for?

What does life include the capacity for?

Growth, reproduction, functional activity and continual change

What is the smallest entity with all the characteristics of life?

The cell

What are the five characteristics of life?

Organisation

Nutrition

Excretion

Responsiveness

Reproduction

In what order does organisation increase?

Atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, biosphere

What is a molecule?

Groups of atoms that are chemically joined. Each element has a particular number of atoms

What is an organelle?

Very large groups of different molecules, which carry out particular functions within the cell

What are some examples of organelles?

Nuclei, mitochondria, chloroplasts, ribosomes etc.

What is a cell?

The basic unit of living things. The consist of organelles suspended in a fluid cystol, surrounded by a cell membrane

What can organisms be in terms of cells?

Unicellular or multicellular

What are tissues?

Groups of similar cells working together to carry out a particular function

What are some examples of tissues?

Muscle, nerves, xylem, mesophyll etc.

What are organs?

Groups of different tissues working together to carry out a particular function

What are some examples of organs?

Lungs, skin, root, leaf etc.

What are organ systems?

Groups of organs that work together to carry out a particular function

What are some examples of organ systems and what do they include?

Circulatory system (heart, arteries, capillaries, veins), nervous system (brain, spinal cord, receptors, sensory neurons, synaptic junctions, motor neurons)

What are organisms?

Individual living entities ranging in complexity

What are some examples of ‘simple’ organisms?

Bacteria, algae, etc.

What are some examples of ‘complex’ organisms?

Flowering plants, mammals, etc.

What are populations?

Groups of individuals of the same species living together and interacting with each other and the environment

What are communities?

Groups of different species interacting with each other in an ecosystem

What are ecosystems?

Biotic factors interacting with each other and their abiotic environment

What are some examples of biotic factors?

Plants, animals, microorganisms, etc.

What are some examples of abiotic factors?

Soil, water, air, pH, temperature, etc.

What are biospheres?

Parts of the Earth where life exists

What are some examples of biospheres?

Air, water, land, underground, etc.

What is nutrition?

The process by which an organism obtains the energy and materials it needs from it’s environment to live, grow and reproduce

What are the two types of organisms?

Autotrophs and heterotrophs

What are the two types of autotrophs?

Photosynthetic and chemosynthetic

What are photosynthetic organisms?

Organisms that get their energy from light (green plants etc.)

What are chemosynthetic organisms?

Organisms that use chemicals to get their energy (bacteria)

What are heterotrophs?

Organisms that obtain their food by eating other organisms

What are the five types of heterotrophs?

Herbivores

Carnivores

Omnivores

Decomposers

Detritus feeders

What is excretion?

The removal of waste products of metabolism that would otherwise interfere with the proper working of the cell or organism

How much do plants excrete?

Plants have little need for excretion

What do plants excrete?

Oxygen during photosynthesis and carbon dioxide when respiring

Where do plants excrete from?

The stomata in the leaves

How much do animals excrete?

They produce a lot of waste

How do simple and small organisms excrete?

Allow the toxic compounds to diffuse into their surroundings

What is responsiveness?

The ability of an organism to detect changes in its environment and alter its position or behaviour accordingly to maintain favourable conditions

What do plants respond to?

Light, gravity, touch and water

Are a plants responses fast or slow?

Slow

What do plant responses usually involve?

Growth towards or away from the stimulus

What do animals respond to?

Light, sound, temperature, smell and movement

Do animals have fast or slow responses?

Fast

What are some examples of the specialised organs that animals have to detect environmental changes?

Eyes, ears, nose, etc.

What does an animals response usually involve, and what is this process called?

The movement of the whole organism from one location to another in a process called locomotion

What is reproduction?

The ability of an organism to make new organisms of the same type

What is replication?

The process viruses use to produce new virus particles

What are the two types of reproduction?

Sexual and asexual

What does sexual reproduction involve?

The production and fusion of gametes, one male and one female

What organisms prefer sexual reproduction and why?

Preferred in advanced organisms and it leads to variation which allows evolution

What does asexual reproduction involve?

One parent

What organisms use asexual reproduction and what are some examples of these?

Primitive organisms such as bacteria, amoeba, etc.

What are the offspring that result from asexual reproduction?

Identical to the parent

What is an example of an organism that uses both types of reproduction?

Aphid

What is parthenogenesis?

The process of giving birth to live young that develop from an unfertilised egg

What three characteristics are not accepted as characteristics of life?

Growth

Respiration

Movement

What is growth?

An increase in the size or number of cells of an organism

What is respiration?

The production of energy in the form of ATP by breaking down complex molecules into simple ones

What is movement?

The self generated change of posture or position of an organism in response to an external or internal change in its environment

What does the continuity of life mean?

All living cells are derived from other living cells

What is a viruses structure?

Very simple, consisting of only a protein coat and either DNA or RNA. They lack cellular structure and organelles

Why did scientists believe that viruses were living?

They were intimately associated with disease

Why are viruses non-living?

They are non-cellular, have no organelles and have only one type of nucleic acid

What virus was crystallised, leading to viruses being declared non-living?

Tobacco mosaic virus