Complete notes in form of PDF file for second unit "Energy" in Years 4/5 of IB MYP Biology course. Notes cover following topics:
- photosynthesis,
- cellular respiration,
- food chains, pyramid of energy.
● Define energy.
Power derived from the utilization of physical or chemical resources, especially to
provide light and heat or to work machines.
● List the sources of energy.
Most energy sources for doing work are nonrenewable energy sources:
- Petroleum;
- Hydrocarbon gas liquid;
- Natural gas;
- Coal;
- Nuclear energy.
The major types or sources of renewable energy are:
- Solar energy from the sun;
- Geothermal energy from the heat inside the earth;
- Wind energy;
- Biomass from plants;
- Hydropower from floating water.
● Describe different kinds of energy (kinetic, chemical, electrochemical, elastic,
radiant, thermal).
Type Description
Kinetic The energy that object possesses due to its motion.
Chemical The energy stored in the bounds of chemical compounds.
, Electrochemical The energy we normally call the conversion of chemical energy
into electrical energy or vice versa.
Elastic The energy that is the mechanical potential energy stored in the
configuration of a material or physical system as it is subjected
to elastic deformation by work performed upon it.
Radiant The energy of electromagnetic and gravitational radiation.
Thermal The energy contained within a system that is responsible for its
temperature.
● Explain changes to the form of energy.
Light energy to chemical energy: production of foods by photosynthesis
Chemical energy to light energy: bioluminescence in fireflies
Nuclear energy to heat and light energy: transformation done by sun
Chemical energy to mechanical energy: conversion of food by our bodies
Electrical energy to kinetic energy: electric fan
Electrical energy to light, heat and sound energy: lightning
Kinetic energy to potential energy: throwing a ball in the air
● Define photosynthesis as the fundamental process by which plants manufacture
carbohydrates from raw materials using energy from light.
The process by which green plants and some other organisms use sunlight (light energy) to
synthesize nutrients (produce glucose) from carbon dioxide and water (simple inorganic
molecules). Photosynthesis in plants generally involves the green pigment chlorophyll and
generates oxygen as a by-product. Plants make food inside their cells. It happens in tiny
green bodies called chloroplasts in a process called photosynthesis. Photosynthesis is a
source of all our food and all our oxygen. A chloroplast is like a tiny factory. As Helmont saw,
one of the key raw materials is water. But he couldn’t see the other raw material, an
invisible gas in the air called carbon dioxide. The chloroplast uses the energy in sunlight to
combine the carbon dioxide and the water into a kind of sugar called glucose. The sun’s
energy is stored in the glucose. The reaction also makes oxygen, which is released to the
atmosphere. The plant uses the sugar’s energy to make all the other materials it needs to
grow.
, ● Investigate the necessity for chlorophyll, light and carbon dioxide for
photosynthesis, using appropriate controls.
Chlorophyll - a green pigment, present in all green plants and in cyanobacteria, which is
responsible for the absorption of light to provide energy for photosynthesis.
Chlorophyll's job in a plant is to absorb light—usually sunlight. The energy absorbed from
light is transferred to two kinds of energy-storing molecules. Through photosynthesis, the
plant uses the stored energy to convert carbon dioxide (absorbed from the air) and water
into glucose, a type of sugar.
● Describe the intake of carbon dioxide and water by plants.
During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and
soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon
dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the
carbon dioxide into glucose.
● Explain that chlorophyll traps light energy and converts it into chemical energy for
the formation of carbohydrates and their subsequent storage.
The stacks (thylakoids) and lamella contain the "pigment" which we like to call "chlorophyll".
This chlorophyll traps light and converts it to the "chemical energy" or "fuel" needed to
allow water and CO2 to form carbohydrates and oxygen. Light energy is converted to
chemical energy when a photochemically excited special chlorophyll molecule of the
photosynthetic reaction center loses an electron, undergoing an oxidation reaction.
● State the balanced equation for photosynthesis in symbols [word equation and
chemical equation].
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