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Plant and Animal Responses to Environment

Apr 30, 2025

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Lecture Notes: Bio 3.3 - Plants and Animals and Their Responses to External Environment

Introduction

  • Speaker: Emma Campbell, Biology teacher at Wellington High School
  • Platform: Study It, an educational forum for student assistance
  • Focus: Bio 3.3 - How plants and animals respond to external environments

Key Topics

Overview of Plant and Animal Responses

  • Biotic Environment: Living world interactions
  • Abiotic Environment: Non-living world interactions
  • Intraspecific Relations: Interactions within the same species
  • Interspecific Relations: Interactions between different species
  • Orientation in Space: How organisms orientate themselves spatially
  • Orientation in Time: Biological rhythms and timing

Achievement Criteria

  • Achieved: Identify and describe biological responses
  • Merit: Explain how and why these responses occur
  • Excellence: Link ideas and context together, explaining adaptive advantages

Plant Orientation in Space

Nastic Responses

  • Movement in response to stimuli, e.g., flowers opening/closing

Tropisms

  • Phototropism: Growth towards light, governed by hormone auxin
  • Geotropism: Growth in response to gravity, roots vs. shoots' directionality

Adaptive Advantages

  • Allow plants to orient correctly for optimum survival and reproduction

Animal Orientation in Space

Taxis

  • Movement towards/away from stimuli, e.g., earthworms moving away from light

Kinesis

  • Changes in movement speed or direction in response to environmental conditions

Long-Distance Orientation

  • Homing: Return to a specific location
  • Migration: Long-distance movement, driven by environmental cues and requiring navigation skills
  • Adaptive Advantages: Avoid unfavorable conditions, improve breeding opportunities

Plant Orientation in Time

Photoperiodism and Phytochrome System

  • Phytochrome Red/Far Red: Pigment conversion regulates flowering
  • Long/Short Day Plants: Flowering controlled by night length
  • Adaptive Advantages: Synchronize flowering with optimal environmental conditions

Animal Orientation in Time

Biological Rhythms

  • Endogenous Rhythms: Internally driven, e.g., tree weta activity
  • Entrainment: Synchronization to environmental cues
  • Phase Shift: Adjustment to new light/dark cycles

Adaptive Advantages

  • Predict environmental changes, adapt to seasonal variations

Intraspecific Relationships

Competition and Cooperation

  • Territories: Defensive areas to reduce competition
  • Hierarchies: Social rankings within groups, e.g., wolf packs
  • Group Living: Cooperative strategies to enhance survival

Interspecific Relationships

Types

  • Mutualism: Both species benefit
  • Commensalism: One benefits, the other unaffected
  • Exploitation: Predation, parasitism

Adaptive Strategies

  • Predators and Prey: Evolutionary arms race for survival

Exam Tips

  • Read questions carefully, use evidence from the given context
  • Plan responses methodically with a focus on 'what', 'how', and 'why'
  • Use diagrams and ectograms to guide and support answers

Summary

This lecture provided an overview of how plants and animals respond to their environments, focusing on spatial and temporal orientation, inter and intra-species relationships, and adaptive strategies. The importance of exam strategy was also emphasized, with practical tips on reading and responding to exam questions.

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