Chromosomal crossover in meiosis I
Description

Meiosis is a process where germ cells divide to produce gametes, such as sperm and egg cells. In prophase I of meiosis, chromosomes condense and homologous recombination takes place, leading to genetic variation through chromosomal crossover. This forms a tetrad, which is made up of four chromatids (two sister chromatids per chromosome).

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Worked example: analysing a generic food web
Description

We can analyse the arrows in a food web to identify producers, primary consumers, secondary consumers, and decomposers.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Worked example: analysing an ocean food web
Description

We can analyse the arrows in a food web to identify producers, primary consumers, secondary consumers, and decomposers.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Matter and energy in food webs
Description

Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Comparing animal and plant cells
Description

Plant cells have a cell wall in addition to a cell membrane, whereas animal cells have only a cell membrane. Plants use cell walls to provide structure to the plant. Plant cells contain organelles called chloroplasts, while animal cells do not. Chloroplasts allow plants to make the food they need to live using photosynthesis.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Khan Academy
Cells and organisms
Description

All living things are made up of cells, which is the smallest unit that can be said to be alive. An organism may consist of one single cell (unicellular) or many different numbers and types of cells (multicellular).

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Khan Academy
Introduction to cellular respiration
Description

Cellular respiration is the process by which cells derive energy from glucose. The chemical reaction for cellular respiration involves glucose and oxygen as inputs, and produces carbon dioxide, water, and energy (ATP) as outputs. There are three stages to cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan