Topic Summaries
Tropisms
Transport Systems
Blood and heart disease
Stem cells, microscopy, and microorganisms
Transport in cells
Human health and enzymes
Plant transport systems
Pathogens and non-specific immunity
The immune system and drugs
Plant disease and monoclonal antibodies
Photosynthesis and respiration
The nervous system and homeostasis
The brain and the eye
Hormone regulation and waste excretion
Reproductive hormones and plant hormones
Cell division, reproduction, and DNA structure
DNA synthesis and inheritance
Genetic engineering and modification
Evolution and natural selection
Species and classification
Resource cycles and environmental change
Biodiversity and environmental management
Biomass and trophic levels
Food supply and biotechnology
Science skills: Experimental procedures
Science skills: Presenting and using data
Science skills: Measuring results
Transport Systems
Blood and heart disease
Stem cells, microscopy, and microorganisms
Transport in cells
Human health and enzymes
Plant transport systems
Pathogens and non-specific immunity
The immune system and drugs
Plant disease and monoclonal antibodies
Photosynthesis and respiration
The nervous system and homeostasis
The brain and the eye
Hormone regulation and waste excretion
Reproductive hormones and plant hormones
Cell division, reproduction, and DNA structure
DNA synthesis and inheritance
Genetic engineering and modification
Evolution and natural selection
Species and classification
Resource cycles and environmental change
Biodiversity and environmental management
Biomass and trophic levels
Food supply and biotechnology
Science skills: Experimental procedures
Science skills: Presenting and using data
Science skills: Measuring results
- Plants produce hormones called auxins to coordinate and control growth in response to light (phototropism) and gravity (gravitropism or geotropism).
- Auxins are produced in the tips of shoots and roots.
- Unequal distributions of auxin cause unequal growth rates in plant roots and shoots.
- Phototropism:
- Plant shoots grow towards the light (positive phototropism) to maximise the light absorbed for photosynthesis.
- In shoots, auxin causes cell elongation.
- Auxins will concentrate on the shaded side of the shoot, causing unequal growth that makes the shoot bend towards the light.
- Gravitropism:
- Plant roots grow downwards towards water (positive geotropism) in response to gravity, while plant shoots are negatively gravitropic.
- In roots, auxin slows cell growth on the lower side, causing curvature downwards.
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