IP Combined Science Notes (Lower Sec, Year 1-2): 06) Transport Systems in Humans & Plants

Study guide11 Dec 2025, 00:00 Z

Track nutrient and gas transport in humans and plants, including circulation, transpiration, and phloem flow calculations.

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Q: What does IP Combined Science Notes (Lower Sec, Year 1-2): 06) Transport Systems in Humans & Plants cover?
A: Track nutrient and gas transport in humans and plants, including circulation, transpiration, and phloem flow calculations.

Transport systems move substances efficiently over distances too large for diffusion alone. Understand structure-function relationships to explain oxygen delivery, sugar transport, and water movement.

These notes align with MOE's Lower Secondary Science syllabus themes commonly taught in IP Sec 1-2, and act as a bridge into upper-secondary Physics, Chemistry, and Biology.

Status: MOE Lower Secondary Science syllabus (current release) checked 2025-11-30 - scope unchanged; remains the reference for these combined science notes.

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The core idea is simple: Transport systems move substances too far for diffusion alone.

Use it as a working check: In humans, track blood through heart, lungs, and body. In plants, separate xylem water transport from phloem sugar transport.

Then go one layer deeper: Example: exercise raises heart rate and stroke volume, so cardiac output rises and more oxygen reaches working muscles each minute.

Learning targets

Describe the structure of the human circulatory system and pathway of blood flow.
Use cardiac output formulas to solve numerical problems and compare fitness levels.
Explain the roles of xylem and phloem, including adaptations for their functions.
Analyse factors affecting transpiration rate and interpret potometer data.

1 Human circulatory system

Key components: heart (four chambers), blood vessels (arteries, veins, capillaries), and blood.

Vessel	Structure	Function
Artery	Thick muscular walls, small lumen.	Carry blood away from heart under high pressure.

Reviewed by

Ezekiel Tan·Academic Advisor (Biology)

Sources

MOE - 2021 G2G3 Lower Secondary Science Syllabus (updated Apr 2024) (PDF)

Substance	Main direction at body tissues	Reason to write	Common trap
Oxygen	From blood to body cells	Cells use oxygen for aerobic respiration.	Saying oxygen leaves the body at every capillary.
Glucose	From blood to body cells	Cells need glucose as a respiratory substrate.	Treating glucose like a waste product.
Carbon dioxide	From body cells to blood	Cells produce carbon dioxide during respiration.	Saying carbon dioxide moves into cells for respiration.
Urea and other wastes	From body cells to blood	Blood carries wastes to organs that remove them.	Forgetting that exchange includes wastes, not only gases.

Given information	First check	Calculation move	Common trap
Stroke volume in $\pu{mL.beat-1}$ , heart rate in $\pu{beats.min-1}$	Units already cancel beats.	Multiply to get $\pu{mL.min-1}$ .	Dropping "per minute" from the final answer.
Stroke volume in $\pu{mL}$ , heartbeats counted in $\pu{30 s}$	Convert the count to beats per minute.	Double the 30-second count before multiplying.	Multiplying by the 30-second count and calling it $\pu{mL.min-1}$
Final answer requested in $\pu{L.min-1}$	Convert millilitres to litres.	Divide $\pu{mL.min-1}$

Tissue	Structure	Function
Xylem	Dead, hollow vessels; lignified walls.	Carries water and mineral salts mainly upward from roots to leaves; lignin also supports the plant.
Phloem	Living sieve tube elements with companion cells.	Carries sugars from sources such as leaves to sinks such as growing tissues, roots, fruits, or storage organs.

Plant situation	Source to name	Sink to name	Direction to explain	Common trap
Sunny mature leaf feeding a growing shoot	Leaf making sugars by photosynthesis	Growing shoot tip	From leaf to shoot	Saying phloem always moves upward.
Leaf sending sugars to roots for storage	Leaf making sugars by photosynthesis	Root storage tissue	From leaf to roots	Treating roots as only water-absorbing organs.
Germinating seedling before many leaves open	Stored food in seed or storage organ	Young growing shoot and root	From store to growing regions	Saying leaves must always be the source.

Factor	Effect on rate
Light intensity	Increases (stomata open for photosynthesis).
Temperature	Increases (higher kinetic energy and evaporation).
Humidity	Decreases (reduced concentration gradient).
Wind speed	Increases (removes saturated air).

IP Combined Science Notes (Lower Sec, Year 1-2): 06) Transport Systems in Humans & Plants

Learning targets

1 Human circulatory system

Sources

Capillary exchange checkpoint

Blood pathway (systemic circuit)

Blood route map

Cardiac output calculation

Cardiac output unit checkpoint

Worked example

2 Blood components

3 Plant transport

Plant transport route map

Phloem source-sink checkpoint

Transpiration factors

Transpiration direction checkpoint

Potometer question

Try it yourself

Related Posts

Question wording	First change to state	Why the rate changes	Common trap
Higher temperature	Faster evaporation from leaf surfaces	More water vapour leaves the air spaces in the leaf	Saying only "particles move faster" without linking to evaporation.
Higher humidity	Smaller water-vapour gradient	Water vapour diffuses out of the leaf more slowly	Saying humid air makes the plant lose more water because there is more water in the air.
Stronger wind	Moist air is removed from around the leaf	A steep diffusion gradient is maintained	Saying wind directly pulls water up the xylem.
Lower light intensity	Stomata may close more	Less water vapour escapes through stomata	Treating light as heat only and ignoring stomatal opening.