biotic and abiotic levels of organisation: 1atom level: consists of atoms of the chemical elements from which living matter is formed: carbon,hydrogen, oxygen, nitrogen, phosporus and sulphur. 2Molecule level: formed by the joining of two or more atoms. 3Macromolecule level: are formed when molecules join together. 4 Organelle level: when macromolecules join together they form organelles. 5 Cellular level (biotic): organelles can be considered as the organs of cells. They come together to form cells, which are the fundamental units of living things. 6Multicellular level: all organisms that contain more than one cell are classified into this level and they are classified in the next sublevels: Tissue sublevel: cell with the same shape and function form tissue. Organ sublevel: organs are formed from different types of tissue that work together to perform a specific function. Organ system sublevel: organ systems are made up of various organs that work together to carry out a specific function. CElls characteristics: Structure and functions: cell membrane: surrounds and protecs the cells. Cytoplasm: contains many different organelles that carry the vital functions. Types: Prokaryotic cells have no nucleus. They are only found in bacteria. Eukaryotic cells have a nucles. They are found in all other things. Human cells: 1 the nucleus contains genetic material 2 the cell membrane protects the cells from the outside 3 this contains the cytoskeleton 4 vacuoles store a variety of substances 5 mitochondria: break down glucose to produce energy as part of cellular respiration. 6 ribosomes produce proteins and are either attached to the RER or are free in the cytoplasm. 7the rough endoplasmic reticulum (rer) stores proteins formed in the attached ribosomes and transports them around the cell. 8 the golgi transports substances to the outside of the cell. 9 lysosomes are involved in digestion within the cell 10 the smooth endoplasmic reticulum produces lipids and breaks down toxic material. Infectious illness: Direct transmission: pathogens are transferred directly from the infected person to another person via physical contact. Indirect transmission: pathogens are transferred via an intermediary, from the host to another person. Internal defences: Acquired inmunity is built up throughout our lives as a result of the body suffering different infections. Lymphocyte B-cells recognise antigens and turn into antibody producing plasma cells. Lymphocyte T-cells that they are able to destroy cells that have been damaged. The nutrition process requieres four closely related systems that work together to perform the necessary functions: the digestive , respiratory, ciruclatory and excretory systems. Is divided in three stages: 1obtaining 2 distributing nutrients and oxygen 3 eliminating. Mouth: the mouth is the entrnce to the digestive tract. Pharynx is a muscular tube that connects the digestive system to the respiratory. Oesophagus: the oesophagus is a muscular tube around 25 cm. Stomach: The stomach is connected to the oesophagus via a sphincter. The liver is the largest internal organ in the body. The gallbladder is a pear-shaped structure located under the liver. The pancreas is a long narrow winth two ducts:the main pancreatic and the accesory duct. The small intestine start at the pylorus and ends at the ileocaecal valve, where it joins the large intestine. The large intestine is connected to the small intestine via the ileocaecal valve. How does our digestive system work: we have two procces: mechanical digestion that food is ground, cut up and mixed with digestive juices to form a paste. Chemical digestion that food is broken down by hydrolytic enzymes. 1preparation of food and digestion in the mouth: three procceses mastication, insalivation and deglutition. 2 deglutition is the movement of the food bolus from the mouth towards the pharynx. 3 gastric digestion is the food going down the oesophagus enters the stomach when the cardiac sphincter relaxes. 4 intestinal digestion: the chyme moves into the duodenum where it is mixed with pancreatic juice, bile and intestinal juice. 5 intestinal absorption: nutrients are absorbed by the intestinal villi. 6 egestion: the substances fermented by the intestinal flora are compacted to form faeces. What makes up respiratory system: 1 nasal cavities 2 pharynx 3 larynx 4 trachea 5 bronchi 6 lungs. Work of respiratory system: Ventilation: air moving in and out the lungs. Gas exchange: oxygen in the air inside the lungs transfers to the blood. Inhalation: air in, chest expands, diaphragm flattens. Exhalation:air out, chest contracts, diaphragm relaxes.