Life On Earth Notes PDF

UNIT 1: LIFE ON EARTH https://www.youtube.com/watch?v=gTsJubN68WE&t=1002s As far as we know the Earth is the only planet in our solar system on which life is developed. Our planet meets the conditions required for living beings to develop: - Our atmosphere protects us from the ultraviolet solar...

UNIT 1: LIFE ON EARTH https://www.youtube.com/watch?v=gTsJubN68WE&t=1002s As far as we know the Earth is the only planet in our solar system on which life is developed. Our planet meets the conditions required for living beings to develop: - Our atmosphere protects us from the ultraviolet solar rays (Ozone Layer). In addition, the Earth has mild temperatures due to the greenhouse effect. The presence of certain gases in the atmosphere, such as carbon dioxide, which retains the Sun heat and maintains an average constant temperature of 15 degrees. The air in the atmosphere provides oxygen and carbon dioxide which is vital for respiration and photosynthesis. - Hydrosphere: Thanks to that average temperature there is water in a liquid state on the Earth. Properties of water are vital for any form of life. - Geosphere provides a layer (magnetic field) which protects us from dangerous solar winds because of movement of the outer iron nucleus. https://m.youtube.com/watch?v=xLvZXKzIjhA 1. Matter in the Universe Matter (living beings and non-living matter) is made up of extremely tiny particles called atoms. These atoms make groups of two or more atoms and these groups are called molecules. Biomolecules are the molecules that composed living beings. There are two types: - Inorganic Biomolecules: Water (It is used to carry out all chemical reactions) and mineral salts (They form the solid structure of living beings such as skeletons. They are also involved in chemical reactions). - Organic Biomolecules: Carbohydrates(storing and transporting energy that we use them quickly), Lipids(to store energy), Proteins (to give structure to cells) and Nucleic Acids (It stores all the necessary information for the functioning and development of living things.)  2. What are living beings like? Living beings carry out the three vital functions: nutrition, interaction and reproduction, which support life. - Nutrition refers to all the processes which enable living things to obtain the energy and matter they need to live. - Interaction with the environment. all the processes which enable living things to react to changes in their environment. For example: plants grow towards the light; animals flee from predators. - Reproduction: refers to all the processes which enable living things to create new living things. 3. The CELL Cells are the structural and functional units of all living beings.There are two types: prokaryotic and eukaryotic cells. Do you know the differences between them? Watch the video: Prokaryotic Vs. Eukaryotic Cells Prokaryotic vs Eukaryotic Cells ( enhanced version) https://edpuzzle.com/media/61718cf966f3cf41b8247e5d Differences between prokaryotic and eukaryotic cells. - Prokaryotes were the first form of life. Scientists believe that eukaryotes evolved from prokaryotes around 2.7 billion years ago. - The primary distinction between these two types of organisms is that eukaryotic cells have membrane-bound organelles and prokaryotic cells do not. - Prokaryotes are bacteria, they are unicellular organisms so they usually have motion systems such as flagellum (flagella) and cilia (cilium). On the contrary, eukaryotes could be pluricellular so they normally don't have a motion system. - Prokaryotes have bacterial walls.. Watch the next video: Comparison Between Plant Cell and Animal Cell Comparison between Plant Cell and Animal Cell ( enhanced) - Bacterial Wall: It’s totally different to the cell wall. Only bacteria have it. Its function is to protect the cell. - Cell membrane: It’s a layer which encloses the cell and regulates the substances exchanged between the inside and the outside of the cell. - Cell Wall: A thick, rigid layer which provides support and protection. It’s only in plant cells. - Cytoplasm: It’s the liquid which fills cells, it is made by water, nutrients and waste substances. - The genetic information is in the nucleus of the cells (eukaryotic cells) or in the cytoplasm (prokaryotic cells), and it transmits hereditary information from one generation to the next. - Nucleus: It’s a double membrane-bound organelle. Only eukaryotic cells have a nucleus. It stores genetic information. In prokaryotic cells this material is loose in the cytoplasm. - Vacuoles:They are sacs filled with water.Only in plant cells. - Centrioles: They control the cellular movement. - Rough Endoplasmic Reticulum: This is where proteins formed in the ribosomes are stored and processed.  - Smooth Endoplasmic Reticulum: This membrane-bound organelle transports and stores lipids. - Golgi Body: This membrane-bound organelle eliminates the cellular wastes. It adapts the proteins in order to realize the necessary functions. - Ribosomes: They make or synthesize proteins. In prokaryotic cells, ribosomes are loose in the cytoplasm. In eukaryotic cells, they are in a wall of a membrane-bound called Rough Endoplasmic Reticulum. - Mitochondrion: It´s a double membrane-bound organelle responsible for cellular respiration (Process to obtain chemical energy from organic matter). The basic equation for cellular respiration is: O2 + Glucose (Carbohydrate)-----ENERGY + CO2 + H2O Watch the video: Mitochondria - Chloroplast: Responsible for photosynthesis (Process to obtain organic matter from inorganic matter). These organelles are only found in plant cells and they are bounded by a double membrane but larger than mitochondria. (See the picture). The basic equation for photosynthesis is: ENERGY (from the sun) + CO2 + H2O ----- O2 + Glucose (Carbohydrate) Watch the video to review all the membrane-bound organelles: Overview of Cell Structure ( enhanced version) 4. Celullar function: A. Nutrition: Nutrition is the process in which living beings obtain the matter and energy necessary to sustain life. Nutrition in pluricellular organisms is composed by different processes to obtain the energy and matter, in order to perform cellular metabolism. a. To obtain nutrients: Living beings can be classified by type of nutrition (how they obtain the matter) as: i. Autotrophs: Living things which make their own organic matter from inorganic matter using a source of energy. (Chemosynthesis, Photosynthesis) ii. Heterotrophs: Living beings which feed on organic matter from inorganic matter. They transform this matter to obtain nutrients and energy. Watch the video: Autotrophs vs Heterotrophs b. Respiration: Intake of oxygen (to perform cellular respiration in each cell, remember mitochondria) c. Substances distribution: Pluricellular organisms need to connect all cells in order to get nutrients and remove waste products (Cytoplasm). d. Excretion: Waste products of metabolism and other non-useful materials are eliminated from an organism (remember golgi body in eukaryotic organisms and cell membrane in prokaryotic organisms). B. Reproduction is the biological process by which new individual organisms are produced. There are two types: - Asexual: requires only one progenitor. The descendant is a copy. - Advantage: the process is faster than sexual reproduction. It is typical of colonising species. - Disadvantage: living beings can’t adapt to the environment, there isn’t variety. - Sexual: requires two parents: a male and a female. The descendant is a mixture between them. - Advantage: the living being can adapt to the environment, there is variety - Disadvantage: the process is slower. It needs water to do reproduction. C. Interaction: Individual living beings relate to their surrounding environment through their cell membrane and golgi body. Moreover, the cell can have movement systems like flagella or cilia.  All living beings relate with their environment through this function. Interaction involves different elements in pluricellular organisms: a. Stimuli. Changes in external or internal environment. b. Receptors. Structures which receive stimuli from external or internal environment. c. Coordination system: Coordination system processes information received from stimuli and produces appropriate responses. This process is different in animals and plants. d. Responsive organs. Also called effectors. They are structures which produce responses.