2.8.1Inquiry Process
Adaptations for Movement — IB Biology HL Revision Notes & Topical Questions
5 min read 4 parts Lesson 86 of 160
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 4Motile and Sessile Organisms
Motile
- Motile Motile organisms can move their whole body or parts of it from place to place, as in most animals and many single-celled organisms.
Sessile
- Sessile Sessile organisms are fixed in one place for most or all of their lives, such as adult sponges, corals and most plants.
Benefits of motility
- Benefits of motility Movement allows organisms to find food, locate mates, escape predators and move away from unfavourable conditions.
Internal movement
- Internal movement Even sessile organisms show movement, such as growth towards light in plants or cytoplasmic streaming in cells.
| Type | Examples | Main way of obtaining resources |
|---|---|---|
| Motile | Fish, birds, many protists | Moving to the resource |
| Sessile | Corals, plants | Resources come to or grow towards them |
Part 2 of 4Structures That Produce Movement
Cilia and flagella
- Cilia and flagella Whip-like or hair-like extensions powered by microtubules move cells such as sperm, or move fluid over a surface.
Pseudopodia
- Pseudopodia Amoeboid cells extend cytoplasm to crawl, using changes in the cytoskeleton.
Muscle
- Muscle Muscle cells contain protein filaments that slide past each other and shorten the cell, producing force.
Skeleton
- Skeleton Rigid or fluid-filled skeletons give muscles something to pull against and transmit force into movement.
Part 3 of 4Types of Skeleton
Types of Skeleton
Hydrostatic skeleton
- Hydrostatic skeleton A fluid-filled body cavity under pressure, as in earthworms, in which muscles act on the fluid to change shape.
Exoskeleton
- Exoskeleton A hard external covering, as in insects, which protects the body and provides attachment for muscles.
Endoskeleton
- Endoskeleton An internal skeleton of bone or cartilage, as in mammals, which supports the body and allows growth.
Muscle attachment
- Muscle attachment Muscles attach to the skeleton by tendons so that a contraction moves the bone or body segment.
Part 4 of 4Exam Checklist & Tips
2.8.1 – Key Points for the Exam
- Motile Able to move from place to place.
- Sessile Fixed in position and not able to move whole-body from place to place.
- Cilia Short hair-like projections that beat to move a cell or fluid.
- Hydrostatic skeleton Support provided by fluid held under pressure in a body cavity.
Common Mistakes
- Describing plants as unable to move at all; they move by growth and by changes in turgor.
- Saying that sessile means 'slow'; it means fixed in place.
- Mixing up exoskeletons (external) with endoskeletons (internal).
- Forgetting that muscles can only pull and never push.
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