ES

Organisation of life

There are 8 characteristics which all living things have in common whether they are plants or animals and these are also the 8 rules that determine whether you are a living organism or not.

  1. Movement

This happens in all living things. Animals use their muscles but plants normally do it by growth.

  1. Reproduction

The production of new organisms

  1. Sensitivity

Responding to changes in the environment called stimuli. A common example are plants growing towards the light such as sun flowers always facing the sun to get maximum sunlight and so more photosynthesis and therefore the most growth.

  1. Control

Control of an internal environment is called homeostasis.

  1. Growth

The permanent increase in size caused by an increase in the size or number of cells.

  1. Respiration

Releasing energy from food(NOT BREATHING). This is stored as a chemical called ATP. The formation of respiration is:

Glucose + Oxygen -> Water + Carbon Dioxide(ENERGY)

  1. Excretion

The removal of cellular or metabolic waste. This is frequently toxic. 2 examples are CO2 from respiration and urea that is found in urine.

  1. Nutrition

Taking in substances that can be used as food

Classification:

Traditionally living things are divided in 5 kingdoms. We put viruses in a different group as they are not considered living (they are unicellular).

Cell structures:

Animal cell:

Plant cell:

Animal Cell Structures:

  1. Nucleus – Contains DNA and controls the cell's activities.

  2. Cytoplasm – Jelly-like fluid where most chemical reactions occur.

  3. Cell membrane – Controls what enters and leaves the cell.

  4. Mitochondria – Site of aerobic respiration, releasing energy.

  5. Ribosomes – Make proteins by assembling amino acids.

Plant Cell Structures:

  1. Nucleus – Same as in animal cells.

  2. Cytoplasm – Same as in animal cells.

  3. Cell membrane – Same as in animal cells.

  4. Mitochondria – Same as in animal cells.

  5. Ribosomes – Same as in animal cells.

  6. Cell wall – Rigid outer layer made of cellulose that supports and protects the cell, it is made of cellulose.

  7. Chloroplasts – Contain chlorophyll and are the site of photosynthesis.

  8. Vacuole – Stores water, nutrients, and waste; helps maintain cell shape.

Structures found inside cells are called organelles. Additionally, mitochondria and ribosomes are not actually visible under the microscope!

Stem Cells:

In the early stages of an embryo’s development, cells look alike and have a simple structure. These unspecialised cells are known as stem cells.

  • Stem cells in an early embryo have not yet undergone differentiation.

  • They have the potential to develop into any type of cell in the body.

As the embryo grows:

  • Cells begin to change shape and structure based on their role.

  • This transformation into specialised cells is called cell differentiation.

Stem cells are vital in early development due to their ability to become any kind of cell needed by the growing body.

Specialised cells:

Animal:

Plant:

The human body and the different systems:

Levels of organisation:

Small structures found inside a cell are called organelles.

A group of similar cells with the same function form a tissue.

A collection of several tissues carrying out a particular function is called an organ.

Different organs working together make up a system.

Different systems within a human body: