AQA Combined Science Biology Chapter One


Chapter 1.4

* As an Organisim develops, Cells differentiate to form different types of cells.

* As an animal cell differetiates to form a specailised cell it acquires different sub- cellular structures to enable it to carry out a function.

* Examples of specailised animal cells are nerve cells, muscle cells and sperm cells. * Animal cells may be specailsed to function within a tissue, an organ, organ systems or whole organisms.

1 of 9

Chapter 1.2

* Animal cell feautures common to all cells - a nucleus, cytoplasam, cell membrane, mitochondria and ribosomes.

*Plant and agal cells contain all the structures seen in animal cells as well as a cellulouse wall.

*Many plant cells also contain chloroplasts and a permanent vacuole filled with sap.

2 of 9

Chapter 1.3

* Eukaryotic cells all have a cell membrane, cytoplasam, and genetic material enclosed in a nucleus.

* Prokaryotic cells consist of cytoplasam and a cell membrane surrounded by a cell wall. the genetic material is not in a distinct nucleus. It forms a single DNA loop. Prokaryotes may contain one or more extra small rings of DNA called plasmids.

* Bacteria are all prokaryotes

3 of 9

Chapter 1.5

* Plant cells may be specailised to carry out a particular function.

* Examples of specailsed plant cells are root hair cells, xylem cells, and pholem cells.

*  Plant cells may be specialised to functionwithin tissues, organs, organ systems or whole organisims.

4 of 9

Chapter 1.6

* Diffusion is the spreading out of particles of any substance, in a solution or gas, resulting in net movement from an area of lower concentration, down a concentration gradient.

* The rate of diffusion is affected by the difference in concentrations, the temprature, and the avalible sureface area.

* Dissolved substances such as glucose and urea gases such as oxygen and carbon dioxide move in and out of cells by diffusion.

5 of 9

Chapter 1.7

* Osmosis is a special case of diffusion. it is the movement of water from a dilute to a more concentrated solute solution through a partially permable membrane that allows water to pass through.

* Differences in concentrations of solutions inside and outside a cell cause water to move into or out of the cell by osmosis.

* Animal cells can be damaged if the concentration outside the cell changes dramatically.

6 of 9

Chapter 1.8

*Osmosis is important to maintain turgor in cells.

*There are a variety of investigations that can be used to show the affect of osmosis on plant tissue.

*Scientists have discovered ways of mesuring the turgour pressure inside cells by using very tiny probes.

7 of 9

Chapter 1.9

* Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient.)

* Active transport uses engergy released from food in respiration to provide the energy required.

* Active transport allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentaration gradient.

* Active transport allows sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher.

8 of 9

Chapter 1.10

* Single celled organisms have a relatively large surface area to volume ratio so all necassary exchanges with the enviroment take place over this surface.

* In multicellular organisims, many organisims are specialised with effective exchange surfaces.

* Exchange surfaces usally have a large surface area and thin walls, which give short diffusion distances. In animals,exchange surfaces will have an efficent blood supply or, for gaseous exchange, be ventitalted.

9 of 9


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Text Book and Revision Guide resources »