IB Biology Topic 3 Cram sheets
This page contains our IB Biology cram sheets for topic 3. By reviewing each one of these cram sheets, you will fully cover the content for IB Biology 'Organisms'.
Subtopic A3.1
Diversity of organisms
Discover the variation of life, understanding the factors contributing to diversity. Explore the methods of categorizing organisms, including binominal naming, species, populations, and genomes.
Subtopic A3.1
Further diversity
Discover the classification of asexually reproducing species and bacteria. Explore the role of chromosome number in breeding combability, applying methods such as barcodes and dichotomous keys to investigate biodiversity.
Subtopic A3.2
Classification & cladistics
Explore the classification of organisms, understanding the hierarchy of taxa and cladistics. Consider the criteria on which classification is based on, including the advantages of this method as well as factors contributing to deviation.
Subtopic B3.1
Gas exchanges
Explore the mechanism of gas exchange, a vital function in all organisms. Consider the conditions required for this process and how this differs amongst, plants and mammals.
Subtopic B3.1
Further gas exchange
Discover the adaptations of haemoglobin in enabling gas exchange, considering how these can be represented using oxygen dissociation curves. Explore the role of carbon dioxide concentration on actively respiring tissues.
Subtopic B3.2
Transport
Discover the circulatory system, understanding the adaptations that sustain mammalian life. Explore the structures comprising plant stems, considering how these sustain plant life.
Subtopic B3.2
Further transport
Explore the movement of fluid and exchange of substances throughout the body, describing the cardiac cycle and considering how the circulatory system varies between fish and mammals. Discover the adaptations of xylem and phloem in plant transport.
Subtopic B3.3
Muscle & motility
Explore the mechanism of movement, an essential feature in all living organisms. Discover the structural adaptations of muscles, joints, and bones in enabling essential functions, including moving and breathing.
Subtopic C3.1
Body systems
Explore the components of the human and animal body. Discover the interplay between the nervous system and hormones in modulating movement, sensation, balance, sleep, pain, ventilation, digestion, and heart rate.
Subtopic C3.1
Plant systems
Discover trophic responses and their contribution to plant growth. Consider the role of auxin, cytokinin, and ethylene in influencing this process.
Subtopic C3.2
Defence against infectious disease
Discover pathogens, considering the adaptations of the human body in preventing infection, including the role of the innate and adaptive immune system. Explore the mechanism of immunity and vaccination, relating this to common infectious diseases.
Subtopic D3.1
Reproduction
Discover the reproductive adaptations of plants and animals, understanding how this contributes to variation. Understand the anatomy of male and female reproductive systems and hormonal adaptations, including the menstrual cycle.
Subtopic D3.1
Further reproduction
Discover the sexual development of males and females, exploring their reproductive adaptations. Explore the role of hormones in pregnancy and delivery, as well as the medical uses of hormone replacement therapy.
Subtopic D3.2
Monogenic inheritance
Explore the production of gametes, considering how variation occurs during their creation. Discover how differences in allele dominance contribute to inherited characteristics, understanding the use of Pedigree charts and box-and-whisker plots in predicting this.
Subtopic D3.2
Polygenic inheritance
Explore gene linkage, understanding how this contributes to characteristics amongst populations. Discover how punnet grids, dihybrid crosses, and chi-squared tests can represent this relationship.
Subtopic D3.3
Homeostasis
Discover homeostasis, the balance of life. Understand the role of negative feedback loops, thermoregulation, and hormones in balancing the bodily functions of humans.
Subtopic D3.3
Further homeostasis
Discover the homeostatic adaptations of the kidneys and circulatory system, understanding how water balance and blood supply is maintained.
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