2020 P BIO - Year 11 Biology Study Notes PDF

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Summary

Year 11 Biology Study Notes
Preliminary Biology Study Notes
Module 1 including 'Cells and the basis of life'
Module 2 'Organisation of Living Things.'
Module 3
Module 4...

Description

Biology Study Notes A Local Ecosystem Ecology: Study of living things and their environment

Ecosystem: Comprises of all abiotic and biotic features and environment of an area

Community: All the living things within an ecosystem, all the different types and individual organisms

Population: All the individuals of a particular species living within the same ecosystem

Transect Study: -

Cross-section through a study area to analyse the distribution of organisms in that area Used for stationary organisms such as plants

Quadrat Sampling: Estimated = Average count x Study area Population -

per quadrat

Quadrat area

Use of a quadrat to determine the average number of organisms per quadrat Used to determine abundance / population of an organism Used for stationary, slow moving organisms

Capture Recapture Sampling:

Estimated Population

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= 1st capture x 2nd capture no.marked in 2nd capture (no. re-captured)

Capture a number of species being studied Mark or tag the animals Release the animals back into the environment Carry out a second capture program Count how many of the 2nd capture are marked from the 1st capture

Relationships between organisms: Allelopathy - The chemical restraint of one plant by another Example - Pine trees drop their needles to the ground and they begin to decompose and release acid into the soil Parasitism - Relationship in which one organism feeds on another without killing it, or even necessarily harming it significantly. Example - Mosquitoes benefit, humans are harmed Mutualism - An interaction which is beneficial to both organisms involved Example - Beneficial to Oxpecker (a type of bird) and Zebra, Cows and Methanogens Commensalism - Relationship where one organism benefits while the other is neither harmed nor helped Example - Cattle Egrets and Cattle, Bird and tree

Competition: Competition occurs when two different species rely on the exact same sources. These include food or living space. Competition consist of two species and results in a winner and a loser. As one will be more successful than the other, this causes their population to grow, while the loser will decline in numbers and eventually may becomes extinct.

Resource partitioning: In some cases, two species of organisms who seem likely to be competing with each other. For example the lion and leopard often live in the same areas and feeding on the large amounts of animals. However, it is shown that their hunting patterns and techniques are different that they naturally tend to prey on different species and categories allowing each other to survive in the same habitat.

Eutrophication: Occurs when rivers and streams are over fertilised by human sewage or agricultural run off. Results in algae blooming which cover the surface of rivers and streams, preventing the penetration of sunlight, hence effecting photosynthesis rates

Patterns in Nature Cells: -

All living things are composed of cells Multicellular organisms are composed of more than one cell e.g. Organisms Unicellular organisms are composed of one cell e.g. Bacteria CELL → TISSUE → ORGAN → SYSTEM → ORGANISM

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CELL → Basic units of any living thing

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TISSUE → Single cells working together (e.g. muscle tissue)

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ORGAN → Combination of tissues (e.g. heart)

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SYSTEM → Organs working together for a specific purpose (e.g. digestive system)

Cell Theory: -

All living organisms are composed of cells or are the product of cells (e.g. Viruses) All cells are produced from pre-existing cells Cells are the basic units of life

Cell Size: Bacteria Cells → Animal Cells → Plant Cells (Smallest to Largest)

History of Cell Knowledge: -

Robert Hooke 1665, First person to see and name cells, used a primitive microscope, observed a piece of cork and viewed small tine “boxes” Anton van Leeuwenhoek 1676, Used a simple microscope, equipped with an excellent lens, viewed micro-organisms swimming around in a drop of water Robert Brown 1827, First to discover the structures inside cells, discovered and described the nucleus inside plant cells Rudolf Virchow 1859 and Walther Flemming 1879, clarified the process of cell division, by which cells produce more cells, established the principle that all cells come from pre-existing cells

Animal and Plant Cells: -

Nucleus → Contain genetic material (chloroplast and DNA) which controls the activities of the cell, site for the production of RNA

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Cytoplasm → Most chemical processes take place here, controlled by enzymes

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Endoplasmic Reticulum → Network of membranes that form channels and compartments throughout the cytoplasm, structure provides channels for chemicals to travel accurately and for chemical productions to occur, ribosomes are attached to E.R, the site of protein production

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Cell Membrane → Boundary of the cell, controls the movement of substances into and out of the cell, built from lipids and proteins

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Mitochondria → ATP produced by respiration carries chemical energy all over the cell

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Ribosomes → Protein synthesis happens here

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Golgi Apparatus → Semi-circular arrangement of membranes which pack chemicals into small membrane sacs (vesicles) for storage or secretion, lysosomes are a type of vesicle produced, these vesicles contain digestive enzymes which can destroy any foreign proteins which enter the cell, lysosome enzymes rapidly digest the contents of a dead cell

Extra Parts of Plant Cells: -

Cell Wall → Strengthens the cell

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Chloroplasts → Contains chlorophyll, which absorbs light energy for photosynthesis

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Permanent Vacuole → Filled with cell sap to help keep the cell enlarged and swollen with water

Importance of Membranes, Membranes Provide: -

The infrastructure of the cells Channels for chemicals to move through Packing for chemicals which need to be stored Control over what moves in or out of each organelle, and in or out of the entire cell

Organic Chemicals: Chemicals based on the element carbon, which can form chains, rings and networks -

Carbohydrates → Sugar, Starch, Glycogen, Cellulose and Lignin, can be converted to fat for storage

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Lipids → Fats and oils, used as a way to store excess energy food

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Proteins → Main structural chemicals of organelles, cells, bone, skin, hair, life is built from proteins, made from amino acid molecules joined in chains

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Nucleic Acids (RNA and DNA) → DNA is the genetic information of every cell, RNA is the messenger sent out from the nucleus to control all cell activity

Structure of the Cell Membrane: -

Phospholipid molecules are the basic chemical unit

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Two molecules thick Each molecule has two distinct ends

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One end is attracted to water → Hydrophilic

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One end is repelled by water → Hydrophobic

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Two layers of phospholipids form each layer Molecules cling to each other and line up with their hydrophilic ends outwards

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Hydrophobic ends are repelled from water surroundings and cling together inside the membrane Phospholipid bilayer

Diffusion: -

Movement of dissolved chemicals from high concentration to low concentration

Osmosis: -

Special case of diffusion Diffusion of water through a semi-permeable membrane, against the concentration of solutes Occurs when solutes cannot penetrate the membrane but water can

Surface Area to Volume Ratio: -

Surface area increases, Volume increases, SA / VOL ratio decreases Surface area decreases, Volume decreases, SA / VOL ratio increases

Autotrophs: -

An organism that produces it’s own food, all plants are autotrophs, making their food through the process of photosynthesis

Heterotrophs: -

Organisms that cannot make their own food are heterotrophs, all animals are heterotrophs

Photosynthesis: WATER + CARBON DIOXIDE = OXYGEN + GLUCOSE -

Occurs in the chloroplast of plant cells

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Phase 1 → In the grana, chlorophyll absorbs light energy and uses it to split water into hydrogen and oxygen

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Phase 2 → In the stroma, a cycle of reactions builds glucose from carbon dioxide and the hydrogen from the water

Cellular Respiration: OXYGEN + GLUCOSE = CARBON DIOXIDE + WATER -

Production of ATP to power all cellular and life activities

Most important process on Earth: -

Photosynthesis is the most important biological process Makes all the food Makes all the oxygen in the atmosphere

What happens to glucose in plants: -

Glucose is a monosaccharide sugar, type of carbohydrate Plants convert glucose into other types of carbohydrates easily Plants convert glucose to starch, this process occurs so rapidly that there is a starch buildup in leaves Glucose can be converted to lipids, they contain the same chemical elements Minerals such as nitrate, phosphate and sulphate are essential for plants to make protein and DNA

Structure and Function of Plants: -

Plants absorb water through outgrowths on their roots called root hairs Root hairs increase the absorption of water by increasing the surface area Each root hair is part of a cell Absorption is achieved through osmosis, the cell cytoplasm has a higher solute concentration than the water solution in the soil After diffusion, the water diffuses from cell to cell towards the the central xylem tubes Xylem tubes carry the water upwards to the leaves, this is possible since the plant is constantly allowing water to evaporate through its leaves (Process of transpiration) Phloem tubes carry food from the leaves to any part of the plant which cannot photosynthesise Xylem and phloem tubes form the veins in a plant, they also act as reinforcement and support structures

Structure of the Leaf: -

Broad, fat and thin to provide a maximum surface area for absorbing light and carbon dioxide from the air Veins are composed of the xylem and phloem, maintain structure Cuticle is a clear layer of waxy material, it allows light but is waterproof to prevent water loss Epidermis layer of cells are transparent to allow light to penetrate through

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Palisade layer of cells are tightly packed under the top epidermis where there is maximum light, each cell contains many chloroplasts Stomates allow the process of transpiration to occur, allow carbon dioxide to diffuse into the leaf, allow oxygen to diffuse into the air Stomate pores are openings formed between two special guard cells, they open and close to maximise or minimise water loss

Nutrition in Animals: -

The food an animal eats is composed largely of complex carbohydrates, proteins and fats which must be digested before being absorbed into the body and used by cells Digestion involves chemically breaking large molecules down into smaller units which can be carried around the body and transported across cell membranes Chewing the food begins the digestion process, breaks food into smaller pieces with greater surface area An enzyme in saliva begins digesting starch Oesophagus carries food to the stomach Liver receives and processes digested nutrients after they are absorbed into the bloodstream Stomach churns food with acid, enzymes digest proteins in food Rectum stores undigested wastes for later elimination

Different Systems for Different Animals: Herbivores -

Plant material has a low nutritional value and contains a lot of fibrous matter which is difficult to digest Fibre is mostly the plant cell walls, made of cellulose Animals lack the necessary digestive enzymes to break cellulose down Usually have flat, grinding teeth to chew the food thoroughly to increase the surface area exposed to enzymes Long intestines and caecum, for more surface area and longer time available for digestion Bacteria living in their gut which have enzymes to digest cellulose (Mutualism)

Carnivores -

Food is concentrated in its nutritional value, relatively easy to digest Sharp, tearing teeth to cut flesh into chunks for swallowing Relatively short intestines Highly elastic stomach, allows them to swallow a large meal, the stomach acid and enzymes are vital for digesting their high protein meat diet

Requirements for Living Cells, Plants and Animals: -

Absorbs nutrients, water and oxygen Excretes wastes Transports all these chemicals between the cells and the environment

Body Systems in Animals: -

Digestive system Respiratory system Excretory system Circulatory system

Requirements for Gas Exchange: -

Large surface area in contact with the environment Moist gas exchange membrane because the gases must dissolve in water before passing through the membrane by diffusion Close contact with the blood supply to carry gases between cells and the gas exchange organs

Circulatory System: Closed -

Blood is always flowing inside a blood vessel, pumped around by the heart System is highly efficient because the blood can be kept flowing within the vessels, guaranteeing a steady flow of nutrients, gasses and wastes between body cells and the outside environment

Open -

Blood does not always stay inside a blood vessel

Lenticels: -

Simple structure on stems of plants which allow gas exchange to the cells by simple diffusion from the air

Life on Earth Conditions of early Earth: -

Massive oceans existed, only small land masses above the surface of the water, No ozone layer, Large amounts of radiation reached the Earth, No

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free oxygen in the air, Large amounts of volcanic activity; heat, ash, dust and gases into atmosphere, Violent electric storms Atmosphere contained some water vapour, hydrogen , hydrogen cyanide , a lot of carbon dioxide , nitrogen, possibly ammonia and methane . The chemicals of life are contained within the following basic organic compounds: water, carbohydrates, lipids, proteins, and nucleic acids. layer, the frequent violent electric storms, and the volcanic activity of early Earth could have provided the energy for molecules to be formed Lack of ozone

For life to have originated, the following events need to have happened: - The required chemicals need to have been formed - These chemicals need to have come together in a self-replicating body - This body would need to have a form of protection for its contents - It had to be able to use an energy source to replicate itself Theory 1: The chemicals for life came from outer space: - Before an atmosphere was formed, nothing stopped meteorites hitting the Earth - Scientists believe Earth was heavily bombarded with meteorites during formation - Certain types of meteorites, called carbonaceous chondrites, have been found, which contain organic molecules, like amino acids - This provided evidence of organic molecules somewhere else in the universe - This means that the chemicals for life could have come from outer space Theory 2: The chemicals for life were formed on Earth: - Haldane and Oparin suggested that early Earth contained all the basic chemical components necessary for life - They hypothesised that complex organic molecules, like nucleic acids and carbohydrates, could have been created using inorganic molecules through slow reactions using energy from lightning or UV rays. - These complex organic molecules could have collected together on the surface of the oceans, forming a “soup”, which later could have formed cells - The theory was untested until the 1950s, when Urey and Miller tested it in the lab - This experiment proved that, if early Earth did contain those chemicals, life could have formed from inorganic molecules.

Technological advancements: Technology

Uses

Microscope

Enabled the discovery or micro-organisms

Radiometric Dating

Can assign absolute dates to rocks/fossils Has established age of the Earth as 4.5 billion years old

Electron Microscopy

Remains of microbes and mineral nature of rocks can be studied in detail

Gas and Liquid Chromatography Radioactive Tracing Amino Acid and Nucleotide Sequencing Spectrophotometry

Enabled the comparisons between ancient organic material and biological material today

Major stages of evolution Organic molecules - The first stage of the evolution of life was the creation of organic molecules, either through synthesis from inorganic molecules, or from outer space - These organic molecules began to clump together in a “soup” Membranes - A membrane had to be developed to protect the internal environment of the large organic molecule - The internal environment, i.e. the contents began to evolve into nucleic acids and the primitive cell could now replicate Prokaryotic heterotrophic cells - The first and simplest types of cells, like bacteria - No membrane-bound nucleus or membrane-bound organelles - These consumed other organic molecules to provide energy (heterotrophic) Prokaryotic autotrophic cells - Some of the heterotrophic prokaryotic cells developed pigments - These pigments allowed them to use the energy from the sun to create food Eukaryotic cells - These cells had membrane-bound nuclei and organelles - Examples include animals, fungi, plants Colonial organisms - Colonial organisms are groups or colonies of similar cells, eg, stromatolites - All the cells in the colony have the same function; no differentiation - They form when daughter cells from cell division become bound together Multicellular organism - These are groups of cells, where some cells have differing functions from others - Each cell has its own specialised function and all cells depend on each other

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The organism functions as a coordinated whole

The conditions needed for life as we know it are: - Available liquid water - Protection from ultraviolet (UV) radiation - Free oxygen in the atmosphere Water was already readily available; it was everywhere When all oxidisable rock had been saturated with oxygen, due to the increase of photosynthetic organisms, the atmosphere began to fill with oxygen Firstly, the oxygen reacted with the UV radiation, and created ozone When enough ozone was created, it formed an ozone layer This protection from UV rays by the ozone layer enabled more sensitive organisms to develop on Earth Oxygen began to build up and the atmosphere was changed from anoxic (no oxygen) to oxic (has oxygen) The significance was that anaerobic organisms declined, and aerobic organisms thrived The number of photosynthetic organisms rose sharply Today, anaerobic organisms only live in places of low oxygen concentration; swamps and bogs, deep underground, etc. The protection provided by the ozone layer enabled organisms to live on land Aerobic organisms took advantage of the abundant oxygen by evolving a system of producing energy that lies on the presence of oxygen: respiration The energy efficiently produced in respiration enabled organisms to increase in size and in their complexity

Describe technological advances that have increased our knowledge of procaryotic organisms: Structural methods include differences in size and shape, general appearance; type of structures needed for movement; absence, presence ...