Igcse Biology Libro Entero Resumen

FINAL BIOLOGY
RESUMENES DE BIOLOGY POR CAPITULO.

CHAPTER 1
Cells and tissues

Cell structure
• vary in size and shape depending on their function
• cell membrane: boundary enclosing the cell; stops the cell content from escaping, control the substances allowed to enter and leave the cell, maintains the structure of the cell and keep chemical reactions in the cell.
• cytoplasm: thinliquid with particle structures (organelles).Where chemical reactions take place which keep the cell alive by providing energy and making substances that the cell needs. Ribosomes build up the cell's proteins. 
• mitochondria: tiny organelles present in the cytoplasm and are responsible for producing energy from food substances
• nucleus: rounded structure enclosed in a membrane and embadded in thecytoplasm which control the type and quantity of enzymes produced by the cytoplasm; without it cells can't reproduce (mitosis). Inside the nucleus there are thread-like structures (chromosomes) 

Plant cells
• differ from animal cells
• cell wall: outside the cell membrane they have a cell wall, which is not selective like the membrane. Each cell has its own cell wall
• cell vacuole: large,fluid-filled space present in most mature cells; it pushes the cytoplasm aside so that it forms a lining inside the cell wall, this outward pressure on the cytoplasm and cell wall makes plants and their tissue firm
• plastids: contain chlorophyll and starch used for food storage

Cell division
When plants and animals grow, the cells increase in number by dividing. Each cell divided to producetwo daughter cells which may divide again, but usually one becomes specialized and looses its ability to reproduce. Growth is the result of cell division.
In a plant cell, the cytoplasm cannot pinch in the middle so a new cell wall has to be laid between the two daughter cells, and a new vacuole has to be formed.

Specialization of cells
• do a particular job
• develop a distinct shape 
• aspecial chemical change occurs in their cytoplasm 
• the change in shape and chemicals reaction enable the cell to carry out its special function 

Tissues and organs
• organisms that consist of one cell can carry out all the processes necessary for their survival
• larger organisms cannot survive on their own, other specialized cells have to provide them with food and oxygen
• tissue: madeup of many cells of different types
• organs: several tissues grouped together to make a structure with a special function
• system: a group of organs whose function are closely related
• organisms: organs and systems working together
• tissue culture
⁃ the technique by which it is possible to make cells grow in dished containing nutrient solutions by taking a sample of developing animaltissue and separating the cells with enzymes
⁃ cells do not become specialized


Chapter 1, Cells and tissues
1. Strip a piece of epidermis from a teem and place a drop of weak iodine solution on it and under a microscope covered with a cover-slip. The iodine will stain the cell nuclei pale yellow and the starch grains will stain blue. To see chloroplasts, pull a leaf from a moss plant and mountit in water on a slide under the microscope. 
2. Animal cells: cotton buds are rubbed on et inside of the cheek and gums and then drop them into a container of absolute alcohol. The smear on the slide is covered with drops of methylene blue solution

CHAPTER 2
Chemicals of living cells

Cell physiology
• physiology: all normal functions that take place in a living organism
• physiology ofan organism: sum of the physiology of its component cells
• cells need water, oxygen, salts and food
• cells consist of water, proteins, lipids, carbohydrates, salts and vitamins.

Chemical component of cells
• water
⁃ take part in chemical reactions because it can absorb heat without their temperature rising to levels which can damage proteins
⁃ cells are 75% water, if the water content...