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Week 9 - Introduction, Moving Water, Life Cycles, Structural Adaptations, and Plant Needs

Week 9 - Introduction, Moving Water, Life Cycles, Structural Adaptations, and Plant Needs

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Course: Science 7 LearnNet
Book: Week 9 - Introduction, Moving Water, Life Cycles, Structural Adaptations, and Plant Needs
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Date: Monday, 28 September 2020, 10:07 PM


An Overview of the Module



Plants are very important to our lives. Without them complex life would not be able to exist on our planet. There was a time when there were no plants and the atmosphere of the earth contained no oxygen. In the last unit you learned that all food webs began with some form of plant. Why? In this module you will learn all about plants; their parts and their processes. You will go on to learn about their importance in our lives. Let's begin our journey.  

ACTIVITY A: Each Plant Structure has a

Required Readings

Science in Action 7
pages 98 - 101

Science Focus 7
pages 104 - 111


Did You Know...

While most food webs begin with the energy of captured sunlight, there are other webs that do not. Deep down at the bottom of the ocean, around volcanic vents (also called hydrothermal vents) called black smokers, bacteria capture the energy in chemical compounds. This process is called chemosynthesis.

Plants are the foundation of virtually all the food webs on
Earth. They play the important role of capturing the sun's
energy, which is then passed on to other organisms in the
web of life. In this lesson we will examine the basic structure
and function of seed plants. They are many kinds of plants,
but we will only examine those that make seeds.

Just sit back for a moment and think about your own body. Each part of your body has a specialized role to play. Your five senses allow you to receive information about the world around you. Your skeleton provides support, so your not just a big blob on the floor, and it also works with your muscles to allow you to move about. Your digestive system brings nutrition and energy to every cell in you body. As you mature into an adult, your reproductive system will enable you to have children.

Every part of a plant has a specialized purpose (a function)

as well. Can you think of all the main parts that make up a


Roots and stems provide support against the pull of gravity

and they also contain a specialized transport system to

move water and food around. Roots also absorb water and

dissolved nutrients.

Unlike animals, plants can make their own food, which is then used in the plant's cells or stored. Green leaves are the main food factories in plants.

Plants also have a reproductive system - just like you! Plants

can reproduce in many ways. Seed plants use flowers

to make seeds.



Exercise 1.1 - Plants



Exercise 1.2

Lesson 1.2: Plant Processes

ACTIVITY A: Moving Water - It All Starts in the Roots


Required Readings

Science in Action 7
pages 102 - 108

Science Focus 7
pages 107 - 111


Did You Know?

More than 90% of the water that goes into a plant is lost through transpiration!

In this lesson we will be investigating the major activities that go on inside
a plant. Some of the processes are only found in plants. For example, photosynthesis allows plants to make their own food. Other activities,
such as cellular respiration are found in all living things. In this unit, we
will start in the ground and work our way up the plant.

Humans have a pump, called the heart that pushes materials around our

body. But you can tear a plant apart and not find any pumps. So how can

the plant get water all the way to the top of the plant?


Roots have the function of getting water and nutrients from the surrounding soil into the plant. Nutrients are drawn through the cell membrane in the root cells by a process called diffusion.

The movement of water molecules across the cell membrane is called osmosis.

Diffusion is the gradual mixing of substances from an area of high concentration into an area of low concentration.


Osmosis is the diffusion of water across a differentially permeable membrane (like a cell membrane).

That means that only water can freely pass through the membrane and all other materials

can't go through.


Once water is in the plant roots, it must be transported to all the rest of the plant. That may not seem like a big deal in a dandelion, but what about a big tree. I mean a really big tree!


A Process called transpiration delivers
water from the roots to every leaf on the
tree. Under every leaf there are thousands
of tiny holes called stomata. They are there
to allow air to enter the leaf - more about
that later! Because of these holes, water is continuously evaporating from the plant.
This creates a sucking action that continues
to draw water up from the roots. And that's called transpiration!

But what holds the water molecules

together? Read page 103 'Moving Water

Up from the Roots' in the Science in Action


  Exercise 1.2 - Celery Lab

Try it for Yourself: Transpiration in Action


  • A piece of celery, about 15 - 20 cm long, that still has some leaves
  • on it.
  • Some food colouring. (Blue works very well.)
  • A drinking glass half filled with water.

Procedures: 1. Mix some food colouring in with the water. (Make it fairly dark)
2. Cut the bottom off of the celery - about 2 to 3 cm would be fine.
3. Now place the celery into the coloured water so that the leaves are
at the top.
4. Now all you have to do is wait a few hours. Hint: the longer you leave it in
the glass the more the colour will show up in the celery. The leaves will begin to
take on the colour of the food colouring.
5. If you have a magnifying glass look at the underside of the leaves.
6. Next, cut the celery stalk and look at the cross-section inside the
celery. Here you will see the part of the plant transport system that
moves water, because it is now stained by the food colouring.



Complete the assignment below:


ACTIVITY B: Making Food - The Colour Green is the Clue


Required Readings

Science in Action 7
pages 104 - 107

Science Focus 7
pages 110 - 111

Diffusion at Work

Earlier in the lesson, we learned that diffusion works when there is a difference in concentration.

The carbon dioxide is at a higher concentration outside of the leaf than inside it so the molecules of carbon dioxide move through the stomata and into the cells of the leaf.

Since the carbon dioxide molecules are always being used up in the food making process, the carbon dioxide gas is always diffusing into the leaves.

Oxygen is diffusing out of the leaves because its concentration is higher inside the leaf. Oxygen is actually a waste product of photosynthesis.

Leaves are the food factories of the plant. The colour green is the clue to look for. A green chemical called chlorophyll is used in the food making process. This process is called photosynthesis. Leaf size is determined by the amount of light the plant gets. For example, plants in deep forest shade tend to have large broad leaves, while those out in the sun tend to be small or thin. Examine the cross section of the leaf on page 111 in Science Focus, notice that there are air spaces between the cells of the leaf. To understand why this is necessary we must first understand the process of photosynthesis. We will use a word equation to understand the process.
The stem on a dandelion and the trunk of a tree perform the same job.

Plants in a forest setting are sometimes in competition for the sun's light. Those plants that can grow the fastest and highest will capture more of the sun's energy than those below them.

The stem, of trunk, is the portion of the plant that lifts the rest of the plant skyward.

Inside each stem or trunk there is a network of vessels that transports water and food throughout the plant.


is the name of the process that plants use to make food.

Wouldn't it be wonderful when we were hungry if we could just go outside and lay in the sun? Animals can't get their energy directly from the sun, but plants can. Plants make the food they need by a process called photosynthesis.

Have you ever wondered why plant leaves are green? Its because they have a special chemical in them called chlorophyll. Carbon dioxide, a gas, is part of our atmosphere. It enters the leaf through a stoma and travels through the air spaces to reach each cell that produces food. The water is transported up from the roots and moves through the veins in the leaf to the plant cells. When sunlight passes through the leaf the chlorophyll captures some of it and, along with the water and the carbon dioxide it is converted into food.

Scientists have developed shorthand ways of writing and what you see above is called a word equation. You should be able to write out the word equation for photosynthesis.

Transportation in Plants

So far in our learning adventure, we have found out how water, carbon dioxide and oxygen move around, but how does the plant get the food it makes to every cell in it body? Diffusion and osmosis are activities that occur naturally and normally in nature. The plant doesn't need to use up any energy in these processes. But moving food is a different story. The plant makes a food molecule called glucose. Glucose is a sugar molecule and is too big to get through the cell membrane and into the plant's cells. The plant must use a process called active transport to get the glucose into the cells, and that takes energy. Plants must use up some of its energy to move the food around to all the parts like the stem or root or flowers.

Cellular Respiration - Putting the Food to Work

So far, we have discovered that only plants can make their own food. But the next process is common to all living things - including you, me, whales, birds, grass, trees and bacteria. This common process to all living things is called cellular respiration.

By now, in our studies in grade 7 science, we know the plants can make their own food, and that even though animals can't make their own food, they can capture and kill other organisms to get the food they need. So what do all these living organisms do with this food? It is sent to every cell in their body and converted back into energy. This process is called cellular respiration. Look at the word formula for cellular respiration below. Is it different from the photosynthesis formula? Are there any similarities?

The formulas are opposites of each other! The whole wonderful world of living things cycles water, carbon dioxide and oxygen around and around between plants and animals. That is why we are constantly talking about the need for balance in the living world around us.

So, what have we learned?

1. Only green plants can make their own food through a process called photosynthesis.
2. The green part of the plant has a chemical called chlorophyll and it puts together the carbon dioxide, water and the sun's energy to make food.
3. All organisms, including plants and animals, use food for energy in a process called cellular respiration.
4. These processes take place at the cellular level.
5. The plant does not use up any energy in the processes of diffusion and osmosis.
6. Food molecules are too big to move by diffusion so the plant must use what is called active transport to move the food around its body, and this uses up some of the plants energy.

Exercise 1.3

Lesson 1.3 Reproduction of Seed Plants
ACTIVITY A: Life Cycles


Required Readings

Science in Action 7
pages 109 to 115

Science Focus 7
pages 120 and 125


In this lesson you will examine the life cycle of seed plants. Understanding the life cycles of seed plants allows use to grow the food we need to feed the world. You and your family have a garden that allows you to enjoy the flavour and health benefits of fresh vegetables. I hope you enjoy this lesson and can put the information you learn into practice in a small garden of your own. Watching your garden grow can be an amazingl experience.

Life Cycles - What Are They?

A life cycle includes the stages that a living organism goes through from one generation to another. Most organisms go through a life cycle. Humans, like you and I, have a life cycle, and so do seed plants. Let's examine our own first.

The human life cycle begins when a sperm (from the father) and an egg (from the mother) join to form a new human life. The baby grows inside its mother and is then born into this world. The baby grows to a child and then to an adult. Adults reproduce and produce another generation of people. That's the life cycle of a human. Lets now go on and examine the life cycle of a seed plant.

Life Cycle of Seed Plants

If you live in a farming area you are already quite familiar with the life cycle of seed plants. First, a seed in put into the ground. There it germinates and begins to grow out of the ground. Over the growing season the plant grow stronger and taller until it is ready to reproduce. Now the plant grows a flower. The flower is fertilized, possibly by insects such as bees, or perhaps by the wind. The attractive parts of the flower, like the petals or the parts that produce an attractive scent, have now done their job, and begin to die back. The plant now puts most of its energy into producing the seeds. As the seeds mature, they drop from the plant, or are blown away on the wind to begin a new generation of plants when favourable conditions for life return again.

So lets quickly review that again in point form: 1. The seed germinates and grows to a tiny seedling.
2. The seedling grow to an adult plant which contains flowers.
3. The flowers are pollinated and new seeds begin to grow and mature.


Sexual Reproduction in Plants

Seed plants use flowers to sexually reproduce. This means that each flower contains both the male and female reproductive organs.

Sexual reproduction uses up great deal of energy in plants so there must be some real advantage of sexual reproduction over asexual reproduction. In sexual reproduction, the offspring are different from either of their parents. This variation may allow the new plants that grow to survive conditions or disease that their parent plant can't. This advantage is found in all species that reproduce sexually even us! For example, you are a totally unique person. No one else is exactly like you (unless you have a twin).

Activity: Examining the Parts of a Flower

Use your textbook and the Internet to name the flower parts in the diagram below. You will be recording this work in the lab that follows. You could try this document for flower part information: Flower Parts



Pollination is the act of transferring the pollen grains from the stamen to the pistil. Some plants can self-pollinate. In this case the pollen transfers from the stamen to the pistil on the same flower. Many grains like wheat and barley are self-pollinators.

Other plants are cross-pollinated.

This means that the pollen from on flower is transferred to other flowers by wind or animal activity. Our friend the bee is one of the main pollinators of our food crops. Other animals like humming birds, bats and other insects look after the job. In return for their efforts, they are rewarded with nectar that many eat on the spot. There are many professional beekeepers in Alberta who travel with their bees to ensure that crops get fertilized.

Moving On

Other seeds are hidden with fruits such as apples, mangos and kiwi fruit. Why do you think the plant goes to so much trouble and energy to make fruit? Plants need to ensure that the seeds they produce will disperse (spread out) over a larger area. One way to ensure this is to have an animal eat the fruit and then walk or fly away from the plant. When the animal goes 'to the bathroom' (they don't really have bathrooms - but you know what I mean) the seeds are deposited on the ground with a fresh supply of fertilizer. This usually happens a long way away from the parent tree and so the plants can eventually spread out over a large area. Other plants drift on the wind like the dandelion or have barbs on them to catch on an animals fur or our pants. However they do it, they must spread out away from the parent plant. Tumbleweeds have a neat way to do it. The parent plant breaks away from the ground and as it blows around in the wind, the seeds fall off.



Exercise 1.3 - Flower Labelling



ACTIVITY B: Vegetative Reproduction


Required Readings

Science in Action 7
pages 114 - 115

Science Focus 7
pages 118 - 119

Plants can reproduce in two totally different ways. Selective breeders primarily make use of sexual reproduction in plants to slowly change the characteristics of plant. On the other hand, once you have the plant varieties that you wish to use, asexual reproduction can be helpful in maintaining the characteristic which are required. In asexual, or vegetative reproduction the "parent" plant grows new plants from its roots, stems, or leaves.

When plants reproduce asexually, the offspring will have the identical characteristics of their parent. Many trees spread by producing new seedings from their roots. A Poplar, or Trembling Aspen forest can be created from very few parent trees.

Some plants such as strawberries will send out runners to implant in the soil and produce another identical plant. Runners are similar to roots but the move out from the plant above ground.

Man has also found ways to make use of vegetative reproduction through layering, grafting and cutting.

In layering, a branch of a parent plant is bent and pointed back into the soil where it is partially covered. Roots will grow from the buried stem and a new plant with the same characteristics of the old one will form. Eventually the new plant can be cut away and replanted. This is a common technique for blackberry, raspberry, and rose bushes.

Grafting is another use of vegetable reproduction. A shoot or branch from one tree in inserted (grafted) into a fresh cut in another tree. A seal or bandaid is applied to keep out infection and the second plant will grow and become part of the first. This is a common practice with apple trees. As trees take so long to grow this is a way of placing apple branches that will produce hardy fruit on trunks with hardier roots and several years head start in growth. There are trees growing in apple orchard that have numerous varieties of apple grafted onto the same trunk.

Plant growers commercial and residential alike make common use of cutting as a way to make a duplicate of a plant and its characteristics. This method will produce offspring much faster than from seed. They only question that remains is how much of a plant must be cut to make the best types of cuttings.



    ACTIVITY C: Cutting Investigation (This Activity is Optional)
    What are the best type of cuttings to take? Find out in this investigation!


    How well will plant cuttings with one leaf, two leaves, three leaves, and no leaves grow? Note: improvise if you need to ie. cut down the number of cuttings by one, find a partner or two and use the same cuttings to gather data from, etc.


    Form a hypothesis about what you expect to happen at the bottom of each of the plant stems after one week.


    Scissors or utility knife
    Four clear plastic glasses
    Aluminium Foil
    Plant, such as a coleus, begonia, or impatiens


    1. Set out your four cups. Label each cup with the number of leaves which the sample will have. Fill the cup with water and cover the top of the cup with a layer of aluminium foil. Tape the aluminium foil around the edge of the cup to get a more rigid seal.
    2. With a pencil, punch a small hole in the centre of the aluminium foil.
    3. Use the scissors to take four small clipping (approximately 5-7 cm long) from your parent plant. Make sure all the clipping come from the same plant. Take one cutting with no leaves, one with one leaf, one with two leaves, and one with three leaves.
    4. Insert the cut end of the cutting through the hole in the foil, ensure that the bottom of the cutting dips completely into the water.
    5. Place your cuttings in adequate sunlight.
    6. Make drawn observations everyday for one week of the bottom of the stem. Make sure to record the date in your table when you first see roots. Draw what you see on each plant for one week. Use a ruler to measure the length of the roots if necessary.


    Copyright © 2001, the Crown in Right of Alberta, as represented by the Minister of Learning, Alberta Learning, 11160 Jasper Avenue, Edmonton, Alberta T5K 0L2

    Picture and Photos:( For specific picture reference view page source.)
    Copyright © 2000-2001, Copyright © 2001 Jeannie Charrois

    Exercise 1.4

    Lesson 1.4: Plant Structures Vary to Adapt to their Environment

    ACTIVITY A: Structural Adaptations


    Required Readings

    Science in Action 7
    pages 116 to 120


    Science Focus 7
    pages 104 to 106

    All living organisms have special body features that allow them to survive in their ecosystems. These special body parts are called structural adaptations. These might include the spines on a cactus or stinger on a bee.

    In this lesson we are going to look at the structural adaptations of plants. Plants want to grow to their full size, save some food, and produce as many seeds as it can. To do this it must compete with other plants in its environment and keep other organisms from eating it. Some use spines for protection; others might use poison. There is even a rain forest plant that feeds and houses ants and the ants in turn protect the plant from predators and kill other plants that might try to grow near it. As you look at the pictures of different ecosystems on this page, try to think of the adaptations that might be necessary to survive in that environment. So let's move on to the lesson and see other wonderful and interesting adaptations that plants use to survive and reproduce.



    There are two basic shapes of roots, tap roots and fibrous roots. In geographical areas that receive a moderate amount of rain fall, the root systems of plants tend to be quite shallow. But in very dry (arid) areas, like deserts, roots systems can reach far below ground level. You recall that the primary purpose of roots is to draw water and nutrients from the soil. But they also have other uses.


    Many plants have a single root with many, much smaller roots, coming out of it. A carrot is an excellent example of a taproot. The smaller roots and root hairs increase the surface area of the root so that it can absorb more nutrients and water from the surrounding soil.

    Fibrous Roots

    Fibrous roots are all similar in size and spread out in all directions in the soil. Although they tend to be rather shallow in the soil, they are able to pick up moisture very quickly. Prairie grasses have fibrous roots systems. Although the part of the plant we can see above the ground is only a few centimeters high, it may have a root system hundreds of kilometers long!


    Did You Know?

    A desert shrub, called mesquite has been known to produce roots up to 50 meters (164 feet) deep.

    Notice that there is so little light getting through the tree canopy that smaller plants cannot grow here.

    The stems of plants have two functions. First, to function as a pipeline that supplies water and food to all the cells of the plant. Second, to raise the photosynthetic parts of the plant above obstructions such, as other plants, so that it can get the maximum amount of sunlight. Plants actually compete with one another for sunlight. Those plants that can grow the fastest and tallest will win the competition, while the losers become more sickly and grow more poorly. This competition becomes very obvious in rain forest areas. When old trees die and fall over, the sunny space in the forest in leaves creates a competition among the younger plants.

    A Single Trunk Design

    Many trees use this strategy. They put all their energy into one trunk so that it can grow as fast as possible. Many side branches grow from this single trunk and from them even smaller branches. Large trees have been known to have so much leaf area that the leaves could cover a football field!

    Multi-stemmed Plants

    Smaller plants use a different strategy. They send up numerous stems. Some of these stems run along the ground. From this horizontal stem roots grow into the ground and new plants begin to grow. We call these horizontal stems runners. Some stems actually grow under ground and produce large swollen areas called corms. New plants can grow from these corms.

    Stems can be Modified for Other Uses

    Many desert plants have modified stems to hold water. Many species of cactus have stems that are swollen up to hold as much moisture as possible. Their stems are modified in another way - they are green. What plant process goes on in green tissue?

    Photosynthesis takes place in the stem of a cactus not its leaves.


    You will recall from a previous lesson that the main purpose of leaves is to produce food by photosynthesis. But if you go out and examine the leaves from different plants you will find that they look quite different from each other. Plant species have modified their leaves over thousands of years to suite their environment.


    Leaf Size

    If you are able, go out into a nice sunny meadow or play ground and look the shape of the leaves on the plants you find there. In general, you will find that plants that live in sunny habitats have fairly small leaves. Their small leaf size provides them with all the food they need. The sun in these habitats can be very intense and water loss through transpiration can be great as well. Small leaves minimize the amount of water lost. This can be a life saving strategy for grasses and other prairie plants who do not receive a lot of rainfall.

    If you would now step into a shady forest area you would immediately feel and see that it is cooler and more shady than our meadow area. It also feels more humid as well. Low lying plants in this habitat need to use a different leaf strategy for survival. Here, water loss is not a major concern. The main concern is the lack of sunlight. These plants have larger leaves to collect more sunlight.


    Conifer needles are modifies leaves.
    Modified Leaves

    Some species of plant have gone to great lengths to prevent water loss. Coniferous trees, like spruce and pine, have leaves that are in the shape of needles. This reduces the water loss and allows the trees to live in harsh environments where deciduous trees (those with normal leaves) cannot survive. A clear example of this can be found in the mountains. In the river valleys you will a mixture of deciduous and coniferous trees But as you look higher upon the mountain you will see only conifers.

    There is another group of plants that have greatly modified leaves. Cactus plants have modified leaves into spines. This serves two purposes. No photosynthesis takes place in the spines so there is no water loss - a great advantage in a desert. So where does photosynthesis take place? Have you ever tried to touch a cactus? If you have, you will know the second reason for the spines. Food and water are hard to find in a desert, and a cactus contains both of these desirable items. If a cactus can't protect itself, it will be eaten by consumers.

    Leaf Drop

    One strategy we are all familiar with in Canada is leaf drop. As winter approaches, deciduous trees drop their leaves and thicken their sap. This protects the tree against the harsh winter temperatures and water loss. The thickening sap acts like antifreeze in cars. Different trees have different levels of antifreeze. Some plants can get well below -40 degrees Celcius without freezing - other can't. Freezing can be deadly to trees but freezing water expands as it freezes. This process can cause trees to literally explode.



    Flowers have one main purpose- to produce seeds. If its self-fertile, or uses the wind to cross pollinate with other flowers, it doesn't need to use up energy to make flashy colorful flowers, or produce nectar that others can use for food. Conifers, like pines and spruces, have flowers of this kind. They aren't showy because they don't need to be. The wind does their work for them.


    Did You Know?

    Insects see different colors and patterns on flowers than we do. What may appear to us as a dull, ordinary flower actually may have runways and bright colors to attract insects
    But if flowers do depend on other creatures to pollinate them, they must first attract them. They do this with color, odor and food in the form of nectar or extra pollen. Some flowers are even so specialized that only one insect, bird or mammal is attracted to them. Some flowers are designed to be traps that won't allow insects to leave until they have pollinated the flower.



    Seeds are new plants waiting in storage until the right conditions or sunlight, moisture and warmth allow them to germinate. But if they try to grow beside a large parent plant they may not have enough sunlight, nutrients or water. So they need to disperse (to spread out from) their parent's location. There are a number of strategies they might use.
    Many seeds use the wind to move on to new territory. Have you ever blown the seeds from a dandelion. If you did, you were helping the species move on to new territory. What kind of structural adaptation do dandelion seeds have? Maple seeds look like they have two wings on them, while the seeds of popular trees are very small and have fluff attached to them, so that the wind can carry them away.
    Some plants depend on animals to disperse their seeds. In an earlier lesson we learned that plants use fruit to attract and disperse their seeds. Oak Trees supply very nutritious nuts. Animals like squirrels eat as much as they can and then they hide or bury the rest. Although a squirrel's memory is good, its not 100%, so they forget where some are buried. Not only do the seeds get moved away from their parent plant, but many are also nestled deep in the soil where they can begin to grow in the spring.
    Some plants use water to help them disperse their seeds. Coconuts have been known to float to different islands before they germinate and grow into new tree.

    Some seeds are designed to catch onto anything that goes by. They look like they have little Velcro hooks that fasten on to your pants or jacket and my dog looks like a seed factory after we come back from a walk. By the time we yank them off and throw them away, they are many kilometers away from where they started.


    Exercise 1.5

    Lesson 1.5: Plant Needs and Growing Conditions

    ACTIVITY A: Plant Needs


    Required Readings

    Science in Action 7
    pages 121 to 122


    Science Focus 7
    pages 132 to 142


    There are no perfect conditions for all plants. Each plant has adaptations to
    survive under different conditions. All plants need the basics of water, light,
    nutrients, and space. However, the amount required by each plant depends
    on how it has been adapted.

    A Douglas Fir tree will require more moisture than a cactus. A rice crop requires pools of water to grow, yet wheat and barley would drown in this amount of water.


    There is no exercise for this section!

    Section 1 Notes

    You have two attempts to complete this summative quiz and the best mark will be recorded.

    You must wait 15 minutes before you can start your second attempt.

    Click the icon to go to the quiz.