Cells, Tissues and Organ Systems: a full term of science

Ten ready-to-teach lessons for Year 8 Biological sciences. Print this pack and the term is prepared: every lesson comes with a step-by-step plan, the questions to ask, a student worksheet, cut-out cards, an evidence sheet or exit tickets, an assessment kit and worked answers.

Start here: five minutes to Monday

1. Skim the term at a glance on the next page.
2. Print the lesson you need. Each lesson is three A4 sheets: plan, worksheet, and cards, an evidence sheet or tickets.
3. Gather the few items under “You need” on the plan. Most come from the science prep room, the kitchen or the garden.
4. Open the free interactive unit on your board or projector. Every plan tells you which picture to show and when.
5. Teach straight from the plan. Timings, talk prompts, misconceptions and worked answers are all on the one page.

For any Year 8 science teacher

The pack suits a biology specialist and a teacher working outside their own subject alike: each plan explains the idea in plain words, lists the misconceptions students bring, and gives worked answers. The big idea of the term: living things are built in levels, cells into tissues, tissues into organs and organs into systems, and at every level the structure of a part suits its job. Two systems carry the term, digestion in an animal and transport in a plant, and the last lessons show how systems work together to keep the whole individual alive.

Two ways to run each lesson

Every lesson works as one 60-minute block, or as two 30-minute sessions; the split point is marked in every plan. Look ahead: Lesson 6 needs a celery stalk left in coloured water overnight, and Lesson 7 soft, broad leaves from a garden plant.

Safety and care in one look

Nothing in the science room is tasted, not the sugar water and not the bread. Clear nail polish is used in a well-aired room with no flame nearby. Knives for the celery are used on a board, cutting away from the hand. Microscopes are carried with two hands.

The term at a glance

One lesson a week for a term. Each lesson stands on the ones before it, so run them in order where you can.

How the sequence builds

Lessons 1 and 2 build the ladder of organisation and show how tissues suit their jobs. Lessons 3 to 5 follow food through the digestive system: the organs, breaking food down, and absorbing it. Lessons 6 to 8 follow water up and sugar down a plant’s transport system. Lesson 9 shows systems working together, and Lesson 10 brings it together.

Curriculum links (Australian Curriculum V9)

The whole term teaches the Science Understanding descriptor AC9S8U02 quoted on the cover. The lessons also work these Science Inquiry descriptors:

Assessment in this pack

• Every plan ends with “Answers and look-fors”: what meeting the idea sounds like in a Year 8 voice, with working.
• The assessment sheet near the front has a class observation checklist and a three-level rubric.
• Lesson 10 is the summative pair: the two survivors task, plus the “Show what we know” check.

Materials for the whole term

One gathering session covers all ten lessons. Much of the kit is in a science prep room: microscopes, slides and balances. The rest comes from the supermarket, the garden and the school. Two things are worth doing ahead: stand a celery stalk in coloured water the day before Lesson 6, and pick soft, broad leaves from a garden plant on the morning of Lesson 7.

The one-trip list

• From the prep room: microscopes, slides, balances, timers and any prepared slides of tissues you have.
• From the supermarket: celery with leaves, food colouring, sugar cubes, a loaf of bread, clear nail polish and clear sticky tape.
• From home or the garden: string, an old towel and an old cotton sheet to cut squares from, soft, broad leaves and a leafy branch.
• From the school: cups, trays, scissors, knives and boards, tape measures and butcher’s paper.

Safety and care in one look

• Nothing is tasted in the science room: not the sugar water, not the bread.
• Clear nail polish gives off fumes and is flammable: a well-aired room, lids back on, no flame nearby.
• Knives are used on a board, cutting away from the hand; food colouring stains, so wipe spills at once.
• Microscopes are carried with two hands, one under the base.

Assessment without extra work

The term assesses itself. Every lesson plan ends with worked answers and look-fors, and Lesson 10 is the summative pair: the two survivors task, in which students explain how a koala’s digestive system and a gum tree’s transport system keep each one alive, and the final check. This sheet is the place to note what you see along the way.

The three levels

Class observation checklist

A tick a lesson is plenty; the Lesson 10 task and check fill the gaps.

Word wall cards

Cut out the cards and build the wall as the words arrive: tissue, organ, organ system and organism in Lesson 1; mechanical digestion, chemical digestion and enzyme in Lesson 4; villi and absorption in Lesson 5; xylem and transpiration in Lesson 6; stomata and guard cells in Lesson 7; phloem in Lesson 8; respiration in Lesson 9.

Dear families

This term in science, Year 8 studies how living things are organised: cells working together as tissues, tissues forming organs, and organs working as systems that keep a plant or an animal alive. The two big examples are the human digestive system and the system that carries water and sugar around a plant.

Along the way your student will lay out a string model of the eight-metre digestive tract, time sugar cubes dissolving to see why chewing matters, watch coloured water climb a celery stalk, count the tiny pores on a leaf under a microscope, and explain how a koala and a gum tree survive.

Try this at home

• Stand a stick of celery with its leaves in a glass of water with a few drops of food colouring. What has happened by the next morning?
• Chew a piece of plain bread for a long time without swallowing. Does the taste change? (Saliva starts to turn starch into sugar.)
• Tie a clear plastic bag over a few leaves of a garden plant on a sunny morning. What is inside the bag by afternoon?
• Look at a leaf from a gum tree and one from a garden plant. How do they hang on the branch, and why might that matter?

What to ask your scientist

• What is the difference between a tissue and an organ?
• Why is the small intestine so long, and what are villi?
• How does water get from the soil to the top of a tree?
• Why would a problem with the heart make your legs tired?

A small note on care: nothing in the science room is tasted, nail polish is used only in a well-aired room, and everyone washes their hands after handling plants.

Warm regards,

The Year 8 science team

Printed from the free seegongsik Cells, Tissues and Organ Systems teaching pack · seegongsik.com/au/y8/biological/AC9S8U02/pack

Levels of organisation

A many-celled living thing is built in levels. Cells of one kind working together make a tissue; several tissues make an organ; several organs working together make an organ system; and the systems together make the organism. Each level is built from the one below, and the same ladder describes a gum tree and a person. Pairs build four ladders, three from the human body and one from a plant, from sixteen mixed-up cards.

We are learning to

• describe the levels of organisation from cell to organism,
• give an example of each level in an animal and in a plant,
• explain how each level is built from the one below.

Success criteria

• I can build a ladder from cell to organ system and say why each card sits where it does.
• I can explain the difference between a tissue and an organ, with an example.

You need

• the ladder cards (third sheet), one set per pair, and the worksheet (next sheet), one per student,
• a stick of celery and a piece of steak or a picture of muscle, for the opening.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the celery, the board and the ladders in Session A, and Parts B and C in Session B.

Watch for these ideas

• “A tissue is anything soft.” A tissue is a group of similar cells doing one job; bone and blood are tissues too.
• “An organ is any part of the body.” An organ is made of several tissues and has a job of its own, such as the heart.
• “Plants do not have organs.” Roots, stems, leaves and flowers are organs.

Make it easier, make it bigger

• Easier: sort the cards into the four levels first, then split each level among the four ladders.
• Bigger: blood is a tissue, but it is a liquid. Use the meaning of a tissue to argue that it still counts.

Answers and look-fors

• Part A, cell to organ system: digestion B → K → H → M; circulation I → D → O → F; breathing G → N → A → L; plant transport P → E → J → C.
• Part B: cell, the smallest living unit; tissue, many similar cells doing one job; organ, several tissues forming one structure with a job; organ system, several organs working together on one big job; organism, the whole living thing.
• Part C: 1. A tissue is one kind of cell doing one job; an organ such as the heart is several tissues (muscle, nerve, the lining) working together. 2. The leaf: made of several tissues (epidermis, palisade, xylem and phloem), it has its own job of making food. 3. The organism: all the organ systems working together.
• Bigger: blood is many similar cells (red and white) with a shared job, carrying materials and fighting germs; the liquid between the cells does not stop it being a tissue.

Levels of organisation

A. Four ladders

Write the card letters, from the bottom rung to the top.

B. What makes each level?

C. Questions

Build four ladders

Cut out the cards. Build four ladders: put the cell at the bottom, then the tissue, the organ and the organ system on top.

Teacher note: every printed row and column holds one card from each ladder and one from each level, so neighbours never give an answer away.

Tissues: structure fits function

A tissue is a team of similar cells, and the shape of those cells suits the tissue’s job. Muscle cells are long fibres that shorten together; the walls of the air sacs in a lung are one cell thick; xylem is a bundle of hollow tubes with stiffened walls. Plants and animals both have tissues, and some do similar jobs, such as covering or carrying. Students name six tissues from drawings of what each looks like down a microscope, and explain how each one’s structure fits its function.

We are learning to

• identify some animal and plant tissues from their appearance,
• explain how the structure of a tissue suits its function,
• compare tissues in plants and animals that do similar jobs.

Success criteria

• I can name the six tissues and say whether each is from a plant or an animal.
• For each tissue, I can link one feature of its cells to its job.

You need

• the tissue evidence sheet (third sheet), one per pair, and the worksheet (next sheet), one per student,
• if your school has them: microscopes and prepared slides of blood, muscle, lung tissue and a leaf section.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the board and the six tissues in Session A, and the slides and Part B in Session B.

Watch for these ideas

• “Blood is not a tissue because it is runny.” It is many similar cells sharing a job; the liquid between them does not change that.
• “Dead cells are no use.” Xylem cells work because they are dead and hollow: open pipes, with nothing inside to block the water.
• “An organ is made of one kind of cell.” An organ holds several tissues; a leaf has epidermis, palisade, xylem and more.

Make it easier, make it bigger

• Easier: match each drawing to a name from the word bank first, then write one reason together.
• Bigger: xylem cells are dead when they do their job. What does a plant gain from this, and what does it give up?

Answers and look-fors

• Part A: 1 xylem (plant): long, hollow tubes with stiffened walls, joined end to end, carry water up without collapsing; 2 blood (animal): red blood cells in a liquid carry oxygen everywhere; the larger white cells fight germs; 3 palisade tissue (plant): tall cells packed with chloroplasts, near the top of the leaf, capture as much light as possible; 4 muscle tissue (animal): long fibres that shorten together to pull on a bone or squeeze an organ; 5 leaf epidermis with guard cells (plant): a single, tightly fitting layer that protects the leaf, with guard cells that open and close the pores; 6 lung tissue (animal): thousands of tiny air sacs with walls one cell thick, so gases cross quickly into the blood.
• Part B: 1. A short distance for gases to cross, so oxygen reaches the blood quickly. 2. The stiff rings stop the tubes collapsing as water is pulled up. 3. Covering and protecting (leaf epidermis, skin or the lining of the gut), or carrying materials (xylem and blood).
• Bigger: hollow, dead tubes carry water with nothing in the way and need no food themselves; the plant cannot repair or reuse them, and must keep making new xylem as it grows.

Tissues: structure fits function

A. Six tissues

Word bank: Blood; Leaf epidermis with guard cells; Lung tissue; Muscle tissue; Palisade tissue; Xylem.

B. Questions

Six tissues down a microscope

Each drawing shows a tissue as it looks down a microscope. Three come from animals and three from plants.

Teacher note: drawings 3 and 5 come from the same leaf; the names are on the plan.

The digestive system

The digestive system is one long tube from the mouth to the anus, with helper organs, the liver and the pancreas, that pour juices into it. Food is broken down as it moves along; its nutrients pass into the blood in the small intestine, and the large intestine takes back water. Students label the system, model the length of an adult’s tract with string, about 8 m with three quarters of it small intestine, and put the journey of a mouthful in order.

We are learning to

• name the organs of the digestive system and the job of each,
• describe the path food takes through the system,
• explain how the organs work together as one system.

Success criteria

• I can label eight parts of the digestive system and give each one’s job.
• I can put the journey of a mouthful in order and explain why the order cannot change.

You need

• for each group: about 8 m of string, scissors, a metre ruler or tape measure, and four paper labels; a body outline on butcher’s paper for the class,
• the worksheet (next sheet), one per student, and the journey cards (third sheet), one set per pair.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the stomach, the board and the labels in Session A, and the string and the journey in Session B.

Watch for these ideas

• “The stomach is behind the belly button.” It sits high on the left, under the ribs.
• “Food passes through the liver and pancreas.” They add juices to the tube; the food never goes through them.
• “The small intestine is the small one.” It is narrower than the large intestine, but by far the longest part.

Make it easier, make it bigger

• Easier: give the eight organ names as a word bank for Part A.
• Bigger: the small intestine is about 6 m long but fits inside the abdomen. Why might it help to be so long and folded? (Lesson 5 tests your idea.)

Answers and look-fors

• Part A: 1 mouth, teeth chew the food and saliva starts to break down starch; 2 oesophagus, a muscular tube that squeezes food down to the stomach; 3 stomach, churns food with acid and juices that start digesting protein; 4 liver, makes bile, which breaks fat into small droplets; 5 pancreas, makes juices that break down starch, protein and fat; 6 small intestine, finishes digestion and takes the nutrients into the blood; 7 large intestine, takes water back into the blood; 8 rectum, stores the waste until it leaves through the anus.
• Part B: oesophagus 25 cm, 3.1%; stomach 25 cm, 3.1%; small intestine 600 cm, 75%; large intestine 150 cm, 18.8%; total 800 cm = 8 m.
• Part C: B, F, D, H, A, E, C, G. The order cannot change because the tube runs one way, and each organ works on what the one before it has done: food must be broken down before it can be taken in, and taken in before the water is taken back.
• Bigger: a long, folded tube gives the food more time and much more surface to pass through into the blood.

The digestive system

A. The parts

B. A string gut

C. The journey

The journey of a mouthful

Cut out the cards and put them in order, from the first bite to the waste leaving the body.

Teacher note: the cards are printed out of order on purpose; the answer is on the plan.

Breaking food down

Digestion breaks food into molecules small enough to pass into the blood. Mechanical digestion, by the teeth and the churning stomach, breaks food into smaller pieces and gives the digestive juices more surface to work on. Chemical digestion uses enzymes, substances that split large molecules into small, soluble ones. Students time a sugar cube dissolving whole, in four pieces and crushed, as a model of why chewing speeds digestion up, then sort twelve cards into mechanical digestion, chemical digestion and absorption.

We are learning to

• tell mechanical digestion from chemical digestion,
• explain why breaking food into smaller pieces speeds up chemical digestion,
• run a fair test and show the results on a bar chart.

Success criteria

• I can find the mean time for each form of sugar and draw the bar chart.
• I can use the words surface and enzyme to explain why chewing helps digestion.

You need

• for each group: three sugar cubes, three clear cups each with 100 mL of water from the same jug, a spoon, a sheet of paper for crushing and a stopwatch,
• the worksheet (next sheet), one per student, and the digestion cards (third sheet), one set per pair.

Nothing is tasted, even the sugar water.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the opening, the sugar cubes and the board in Session A, and the graph and the cards in Session B.

Watch for these ideas

• “Digestion happens in the stomach.” It starts in the mouth and finishes in the small intestine.
• “Chewing turns food into new substances.” It only makes the pieces smaller; enzymes make the new, smaller molecules.
• “Dissolving is digesting.” Dissolving is our model: the sugar stays sugar, while digestion splits molecules into smaller ones.

Make it easier, make it bigger

• Easier: give one example card under each heading before pairs sort the rest.
• Bigger: predict the time for a cube broken into two, and explain where its bar would sit on your chart.

Answers and look-fors

• Part A, example class means: a whole cube 81.2 s, a cube broken into four 41.4 s, a cube crushed to powder 18.2 s.
• Part C: 1. The smaller the pieces, the faster the sugar dissolved: more of it was touching the water at once. 2. Chewing and churning (mechanical digestion); like the water here, the enzymes can then work on far more surface at once. 3. Only the size of the pieces changed: the same water, amount of sugar and stirring.
• Part D: mechanical B, D, G, H; chemical C, E, F, J, K; absorption A, I, L.
• Bigger: between the whole cube and the four pieces, about 55 to 65 seconds: more surface than the whole cube but less than four pieces.

Breaking food down

A. Three sugar cubes

B. Bar chart

C. Questions

D. Twelve cards

Mechanical, chemical or absorption?

Cut out the cards. Lay down the three grey heading cards, read each card, and sort it.

Teacher note: the piles are not the same size; the answer is on the plan.

Absorption and the villi

Digested food is no use until it passes through the wall of the small intestine into the blood. The inner wall is folded and covered in millions of tiny finger-like villi, each with a network of fine blood vessels just under a wall one cell thick. All this folding gives the small intestine an inner surface of about 30 square metres, around 15 times the 2 square metres of skin on the outside of the body. Students model the villi with towelling and smooth cotton, measure how much water each holds, and link surface area to absorption.

We are learning to

• describe how digested food is absorbed in the small intestine,
• explain how the structure of the villi suits their function,
• use a model and say what it shows and what it does not.

Success criteria

• I can compare the towelling and the cotton with means, and say how many times more the towelling held.
• I can draw a villus and label three features that help absorption.

You need

• for each group: a 10 cm square of towelling and one of smooth cotton cut from old cloth, a balance, a tray of water and a timer,
• the worksheet (next sheet), one per student, and the exit tickets (third sheet).

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the board and the two cloths in Session A, and Parts B and C in Session B.

Watch for these ideas

• “Food is absorbed in the stomach.” Almost all digested food is absorbed in the small intestine.
• “The towelling held more because it is thicker.” Its loops give it far more surface for the same square.
• “The villi soak up food like a sponge and keep it.” The food passes straight through into the blood, which carries it away.

Make it easier, make it bigger

• Easier: give the two means and ask only for the comparison and one reason.
• Bigger: in some illnesses the villi become flattened. Predict what happens to a person’s nutrition, and explain using surface area.

Answers and look-fors

• Part A, example class: towelling 14.5 g, smooth cotton 4 g; the towelling held about 14.5 ÷ 4 ≈ 3.6 times as much.
• Part B: 1. The villi: the loops are like the many finger-like folds. 2. More surface means more food molecules can pass through at once, so absorption is faster. 3. Into the blood vessels inside each villus, and then around the body. 4. 30 ÷ 2 = 15 times. 5. The model shows surface area, but cloth only holds water; real villi pass the food through to the blood, which carries it away.
• Part C, at standard: a finger-shaped villus with a wall one cell thick, blood vessels just inside it, and a label explaining the large surface.
• Bigger: much less surface, so less food is absorbed and the person may lack nutrients even when eating well.

Absorption and the villi

A. Two cloths

B. What the model shows

C. A villus

Exit tickets

Cut out one ticket for each student.

Water up the stem

A plant’s roots, stem and leaves form a transport system. Water and minerals enter through the root hairs and travel up the xylem, bundles of hollow tubes, to the leaves, where water evaporates through tiny pores. Losing water from the leaves pulls more water up behind it. Students stand two celery stalks in coloured water, one with its leaves and one with them cut off, measure how far the colour climbs, and cut across a stalk left overnight to find the coloured xylem.

We are learning to

• describe how water moves from the roots to the leaves,
• find the xylem in a stem and explain how its structure suits its job,
• draw a line graph and use it to compare two treatments.

Success criteria

• I can draw both lines on one graph, with a key, and say which rose faster.
• I can explain why cutting off the leaves slowed the water down.

You need

• for each group: two fresh celery stalks of the same length, one with its leaves, two tall cups of water with a few drops of blue or red food colouring, a knife and board, a ruler and a timer,
• one celery stalk left in coloured water overnight for the class to cut; the worksheet (next sheet) and the exit tickets (third sheet).

Lesson flow (about 60 minutes)

Running two half-sessions instead? Set up the stalks, show the board and cut the overnight stalk in Session A; measure in Session B with fresh stalks set up at its start.

Watch for these ideas

• “The roots suck the water up.” Most of the pull comes from the leaves, as water evaporates from them.
• “Water moves through the whole stem.” It travels in the xylem, the coloured dots, not in every cell.
• “The xylem carries the plant’s food.” Sugar travels in a different tissue, the phloem (Lesson 8).

Make it easier, make it bigger

• Easier: use one leafy stalk only and measure it at 20 and 40 minutes.
• Bigger: predict how a fan blowing on the leafy stalk would change its line, and explain why.

Answers and look-fors

• Part A, example class means after 40 minutes: leaves on 5.2 cm, leaves cut off 2.1 cm.
• Part B: two lines rising steadily from 0; the leafy stalk’s line is steeper, about 0.13 cm a minute against 0.05.
• Part C: a ring of coloured dots near the ridged outer edge of the slice; each dot is a bundle of xylem tubes.
• Part D: 1. Both rose steadily, but with leaves the colour climbed about 2.5 times as far in 40 minutes. 2. Water evaporates from the leaves (transpiration), which pulls more water up the xylem; with no leaves there is little pull. 3. The same coloured water, depth, room and time, and stalks of the same length. 4. Out of the leaves through tiny pores, as water vapour into the air.
• Bigger: a fan carries the water vapour away from the leaves, so they lose water faster and the line becomes steeper.

Water up the stem

A. How high did the colour climb? (cm, example class means)

B. Line graph

Plot both stalks on the same axes, join each set of points, and add a key.

C. The overnight stalk

D. Questions

Exit tickets

Cut out one ticket for each student.

Leaves and water loss

Leaves lose water through stomata, tiny pores that on most leaves are mainly on the underside, each between two guard cells that open and close it. The same pores let in the carbon dioxide the leaf needs to make sugar, so a plant always trades some water for food. Students make clear nail-polish peels of the top and the bottom of a leaf, count the stomata at 400 times, and read the results of an experiment with leaves coated in petroleum jelly.

We are learning to

• describe the structure and job of stomata and guard cells,
• compare the two surfaces of a leaf using counts and means,
• use the results of an experiment as evidence for where water leaves a leaf.

Success criteria

• I can find the mean number of stomata on each surface and compare them.
• I can use the petroleum jelly results to say which surface loses most water, and why.

You need

• for each pair: a microscope, two slides, clear nail polish, clear sticky tape, and two soft, broad leaves from a garden plant (not gum leaves),
• the worksheet (next sheet) and the leaf water loss evidence sheet (third sheet), one each per student.

Safety: nail polish gives off fumes and is flammable. Use it in a well-aired room, with the lid back on between coats and no flame nearby.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the painting, the board and the peels in Session A, and the jelly leaves and Part C in Session B.

Watch for these ideas

• “Plants lose water only by accident.” Open stomata let carbon dioxide in; losing water is the price of making food.
• “Stomata are holes that are always open.” Guard cells close them, at night and when the plant is short of water.
• “Most stomata are on top, facing the Sun.” On most leaves they are underneath, in the shade, where less water evaporates.

Make it easier, make it bigger

• Easier: count stomata on the bottom surface only, in three fields.
• Bigger: the field of view at 400 times has an area of about 0.16 square millimetres. Estimate the stomata in one square millimetre of each surface.

Answers and look-fors

• Part A, example class means: top surface 2.5, bottom surface 26 stomata in a field; about 10 times as many underneath.
• Evidence sheet: losses no jelly 32%, top surface coated 28%, bottom surface coated 9%, both surfaces coated 4%. 1. Coating the bottom cut the loss most, so most water leaves through the bottom surface. 2. Through the cut stalk, gaps in the jelly, or the thin waxy skin. 3. The leaf with no jelly, to compare against. 4. Both point the same way: most stomata, and most water loss, are on the bottom surface.
• Part C: 1. Two guard cells around a pore change shape to open or close it. 2. To let carbon dioxide in for photosynthesis, and oxygen and water vapour out. 3. The underside is shaded and cooler, so less water evaporates there.
• Bigger: top 2.5 ÷ 0.16 ≈ 16; bottom 26 ÷ 0.16 ≈ 163 stomata in each square millimetre.

Leaves and water loss

A. Stomata in a field of view at 400× (example class)

B. What we saw

C. Questions

Which surface loses the water?

The experiment

1. Four leaves of the same size were picked from one plant.
2. Petroleum jelly, which water cannot pass through, was spread on: no surface, the top only, the bottom only, and both surfaces.
3. Each leaf was weighed, then hung by its stalk in the classroom for two days and weighed again.

Sugar down, and the plant as one system

Sugar made in the leaves reaches every part of the plant through the phloem, a tissue of living cells that runs beside the xylem in the veins and the stem. The phloem can carry its load down to the roots or up to growing tips and fruit. In a tree the phloem lies just under the bark, so removing a ring of bark cuts it; farmers once killed trees this way to clear land. Students read what happens to a ring-barked branch, sort twelve statements into xylem, phloem or both, and map what moves where in a whole plant.

We are learning to

• describe the job of the phloem and compare it with the xylem,
• use a ring-barking experiment as evidence,
• explain how roots, stem and leaves work as one transport system.

Success criteria

• I can explain why the bark swells above the ring, and why the leaves stay green for a while.
• I can trace water, carbon dioxide and sugar through a plant.

You need

• the worksheet (next sheet), one per student, and the xylem and phloem cards (third sheet), one set per pair,
• a branch with leaves, or a picture of one, for the opening.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the opening, the board and the ring of bark in Session A, and the cards and the map in Session B.

Watch for these ideas

• “Phloem only carries sugar downwards.” It carries sugar wherever it is needed: down to roots, up to new leaves and fruit.
• “Xylem and phloem are the same tubes.” They are separate tissues lying side by side.
• “A ringed tree dies because water cannot get up.” Water still rises in the wood; the roots starve because sugar cannot get down.

Make it easier, make it bigger

• Easier: read the three heading cards together and sort four cards as a class first.
• Bigger: aphids push their mouthparts into a stem and drink a sugary liquid. Which tissue do they tap, and how could you check?

Answers and look-fors

• Part A: 1. Sugar coming down in the phloem cannot pass the gap, so it piles up and the bark above the ring swells. 2. The wood (xylem) is not cut, so water still reaches the leaves. 3. The roots get no more sugar; when their store runs out they die, and then so does the tree, slowly.
• Part B: water, in through the root hairs, up the xylem; most leaves as vapour through the stomata, some is used to make sugar; minerals, in through the root hairs with the water, up the xylem, used by cells all over the plant; carbon dioxide, in through the stomata, used in the leaf cells to make sugar; oxygen, made in the leaves; most leaves through the stomata, some is used by the plant’s own cells; sugar, made in the leaves, carried in the phloem to the roots, growing tips and fruit, used for energy or stored as starch.
• Part C: xylem B, C, E, I, J; phloem A, F, K, L; both D, G, H.
• Bigger: the phloem, because it carries sugar. Cut a thin slice of the stem where an aphid fed and find where its mouthparts end, or test the liquid for sugar.

Sugar down, and the plant as one system

A. A ring of bark

A ring of bark, with the phloem just under it, was removed from a branch. A few weeks later the branch looked like this.

B. One whole plant

C. Twelve cards

Xylem, phloem or both?

Cut out the cards. Lay down the three grey heading cards, read each card, and sort it.

Teacher note: the piles are not the same size; the answer is on the plan.

Systems working together

No organ system works alone. To release energy, a muscle cell needs glucose and oxygen: the digestive system takes in the glucose, the respiratory system the oxygen, and the circulatory system carries both to the cell, where a mitochondrion uses them. If one organ cannot do its job, every cell that depends on it suffers, which is why the whole individual is affected. Students put two journeys in order, an oxygen particle and the starch in a slice of bread, both ending in the same muscle cell, and then work through what happens when one organ fails.

We are learning to

• describe how the digestive, respiratory and circulatory systems work together,
• explain how failure of one organ affects the whole individual,
• compare how organ systems keep a plant and an animal alive.

Success criteria

• I can put both journeys in order and name the three systems they pass through.
• I can explain how one failing organ affects cells far away from it.

You need

• the journey cards (third sheet), one set per pair, and the worksheet (next sheet), one per student,
• a slice of bread to hold up (not to eat).

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the fist, the journeys and Part B in Session A, and the board and the cases in Session B.

Watch for these ideas

• “Each system works on its own.” The muscle cell needs three systems at once.
• “Food gives you energy in the stomach.” The energy is released inside each cell, in its mitochondria.
• “Breathing and respiration are the same.” Breathing moves air in and out; respiration is the reaction in every cell.

Make it easier, make it bigger

• Easier: give the first and last card of each journey, and ask pairs to fill the middle.
• Bigger: the muscle cell makes carbon dioxide, which has to leave the body. Write its journey in four steps.

Answers and look-fors

• Part A: oxygen E, I, B, G, K, C; starch in bread D, L, H, A, J, F. The systems: respiratory and circulatory for the oxygen; digestive and circulatory for the glucose.
• Part B: 1. In the muscle cell, in a mitochondrion. 2. Glucose + oxygen → carbon dioxide + water, releasing energy. 3. The circulatory system: the heart and blood vessels carry both.
• Part C: An illness fills part of the lungs with fluid: less oxygen reaches the blood, so every cell releases less energy; the person tires quickly; The villi cannot absorb food well: fewer nutrients reach the blood, so cells run short of glucose and building materials even when the person eats; The heart pumps weakly: oxygen and glucose reach the cells slowly, and wastes are taken away slowly; the person tires quickly; Floodwater damages a plant’s roots: less water and fewer minerals reach the leaves; the leaves wilt, the stomata close and less sugar is made.
• Bigger: from the muscle cell into the blood; the heart pumps it to the lungs; it crosses into an air sac; it is breathed out.

Systems working together

A. Two journeys

B. Where they meet

C. What if?

Two journeys to one muscle cell

Cut out the cards. They tell two journeys, mixed together. Separate them, then put each journey in order.

Teacher note: the two journeys are printed mixed and out of order; the answer is on the plan.

Show what we know

The last lesson brings the term together around two Australian survivors. A koala lives on gum leaves, which are tough and low in food, and its digestive system is built for them. A gum tree in a heatwave must keep enough water while still making sugar. Students explain each one with the ladder of organisation and with structure and function. Then each student sits the final check on their own, and the class finishes with the unit quiz on the board.

We are learning to

• explain how an animal organ system and a plant organ system keep the individual alive,
• use structure and function to explain a feature we have not met before,
• show what we know about cells, tissues and organ systems on our own.

Success criteria

• My answers name organs in order, link a structure to its job, and say what the whole organism gains.
• I can back each answer on the final check with an example or a reason.

You need

• the two survivors task (next sheet) and the final check (third sheet), one each per student,
• the interactive unit open for the closing quiz.

Lesson flow (about 60 minutes)

Running two half-sessions instead? Do the task and the partner check in Session A, and the final check and the class quiz in Session B.

Watch for these ideas

• Listing organs without saying what each does to the leaf.
• “Closing the stomata is all good.” It saves water but lets in less carbon dioxide, so less sugar is made.
• Mixing up the levels: a guard cell is a cell, the epidermis a tissue, the leaf an organ.

Make it easier, make it bigger

• Easier: give the four koala organs in a jumbled list to put in order before explaining.
• Bigger: unlike the garden leaves of Lesson 7, adult gum leaves hang straight down and have stomata on both sides. Suggest why.

Answers and marking guide

• Task 1: mouth (teeth grind the leaf into small pieces), stomach (churns it with acid and juices), small intestine (digestion finishes and nutrients pass into the blood), caecum and large intestine (microbes break down the fibre; water is taken back). 2. A very long caecum, about 2 m in an animal about 75 cm long, gives the microbes time and space to break down tough fibre, so the koala gets more food from poor leaves. 3. From the leaves themselves; water is taken back into the blood in the large intestine.
• Task 4: closing stomata keeps water in the leaves, so the tree does not dry out; but less carbon dioxide gets in, so the leaves make less sugar. 5. For example: guard cell (cell), leaf epidermis or xylem (tissue), leaf or stem (organ), transport system (organ system). 6. Each takes in what the whole organism needs and delivers it to every cell: nutrients from food for the koala, water and sugar for the tree.
• Check: 1. cell, tissue, organ. 2. A tissue is many similar cells doing one job (muscle tissue); an organ is several tissues working together with a job of its own (the heart). 3. small intestine. 4. Any two: a wall one cell thick (short distance to the blood), a huge surface from the folds (more food absorbed at once), blood vessels just inside (food carried away).
• Check: 5. xylem. 6. Water evaporates from the leaves through the stomata, which pulls more water up the xylem; without leaves there is little pull. 7. The ring cuts the phloem, so sugar from the leaves cannot reach the roots; the roots use up their store and die, and then the tree dies. 8. Less blood reaches the muscles, so they get less oxygen and glucose and release less energy.
• Bigger: a hanging leaf is lit about equally on both sides, so both sides can take in carbon dioxide; hanging edge-on also keeps the leaf out of the strongest midday sun, saving water.
• Scoring: 1 mark each for 1, 3 and 5; 2 marks each for 2, 4, 6, 7 and 8. The rubric near the front of the pack turns the task and the check into a level.

Two Australian survivors

A. A koala

A koala eats up to about 500 g of gum leaves a day and rarely drinks. Gum leaves are tough and hold little food. Where its small and large intestines meet, a koala has a pouch called the caecum, about 2 m long, where microbes break down the tough leaf fibre.

B. A gum tree in a heatwave

On a hot, dry day, the guard cells in a gum tree’s leaves close many of the stomata.

C. Both

Show what we know

Show what you know about cells, tissues and organ systems. Read each item, then circle or write.

Teacher note: the marking guide is on this lesson’s plan; the rubric near the front of the pack turns the score into a level.