Download 1 roots, nitrogen, geotropism

The Different Parts of Plants
Most plants have three major parts: the root, the stem, and the
leaves. Some plants also have flowers and fruit. Each part of the plant
has a specific job. The roots take in water and minerals from the soil.
The stem moves water and minerals up from the roots to the leaves and
it moves food made by the leaves down to the roots. The stem also
helps support the plant. The leaves collect energy from the sun and use
it to make food for the plant. The flower contains the reproductive
parts of some plants and the seeds are made in the flower. Plants store
the seeds in fruits to protect them.
Materials: plant, naturalist notebook, pencil
What to do:
1. Draw a detailed picture of the plant in your journal.
2. Label all the parts of the plant underlined above.
3. Write the function of each part of the plant.
Roots
When you look at most plants you don’t see the roots because
they are below the ground. They act like sponges absorbing water and
minerals for the plant to live. The roots also anchor the plant to the
ground and some even store food for the plant.
Plants can have a fibrous root system or a taproot. Fibrous
roots grow in all directions near the surface of the ground, but they do
not grow very deep. They help hold the ground together to prevent
erosion (the washing away of earth’s surface). Most taproots grow
deeper than fibrous
roots and some store
extra food made by the
plant, like carrots and
beets.
Questions:
1. Label each of the two root systems.
2. What do the root systems have in common? __________________
_______________________________________________________
3. What is the major difference between the two systems? _________
_______________________________________________________
Roots are divided into three main sections: the epidermis,
cortex, and central core. The epidermis covers the outside of the root
and takes in water and minerals. The frizzy growth on the root is the
root hairs which are part of the epidermis. Root hairs grow out into the
soil to help take in water and minerals. Inside the epidermis is the
cortex. The cortex stores excess food made by the plant and excess
water taken in by the plant. Inside the cortex is the central core, which
runs up the middle of the root.
In the central core there are xylem and phloem cells. These
cells are spread throughout the plant and they have tiny holes in them
which allow materials to flow from cell to cell. The xylem cells take
water and dissolved minerals up through the root and stem to the
leaves. The leaves use this to make food, but sometimes the plant
makes more food then it can use right away. The phloem cells take the
excess food down through the stem to the roots. This excess food is
stored in the cortex until the plant needs it.
Materials: carrot, naturalist notebook, pencil, hand lens
What to do:
1. Carefully examine the root and draw a sketch of it.
2. Obtain a slice of carrot from your teacher.
3. Using the hand lens, examine the slice of carrot.
4. Draw a sketch of the slice using as much detail as possible.
5. Label the epidermis, cortex, and central core.
6. Write the function of each part of the plant.
Questions:
Geotropism & Phototropism
1. Do you see anything growing on the main root? Describe what you
see. ____________________________________________________
_______________________________________________________
2. The __________________ contains both xylem and phloem cells.
3. Roots that grow close to the surface are _____________________.
4. ____________________ carry water and minerals up through the
stem to the leaves.
Nitrogen Cycle
All living things need nitrogen. There is a huge supply of
nitrogen in the air. Most plants can’t use the nitrogen directly from the
air so they convert the nitrogen gas into nitrates in the soil. The
nitrogen is cycled from the atmosphere to living things and back into
the atmosphere. Here’s how it works:
1. Nitrogen in the atmosphere enters the soil either through rain or
through plant and animal decay and waste.
2. Bacteria breaks down the nitrogen into a usable form, nitrates, and
plant roots take in the nitrates dissolved in the water in the soil.
3. Plants use the nitrates for growth and productivity.
4. Animals get nitrogen from eating plants or other animals.
5. Animals return some of the nitrogen through their wastes. They also
return nitrogen to the soil when they die.
6. Decomposers and bacteria break down the nitrogen within the
decaying plants and animals, which returns to the soil and atmosphere.
Plants also decay and return nitrogen to the soil.
7. Plants take nitrates from the water in the soil.
What to do:
Draw a sketch of the nitrogen cycle in your naturalist notebook. Be
sure to label what is happening at each phase in the cycle.
When living things act or make a change, it is in response to
some change in their environment – a stimulus. A stimulus can be
heat, light, sound, electric energy, etc. In general, most animals
respond quickly to stimuli, while plants respond slowly and in many
different ways. A tropism is a plants movement triggered by stimuli.
The term geotropism, or gravitropism, refers to a plant whose roots
grow down into the soil as a response to gravity. Plants commonly
exist in a state of anisotropic growth, where roots grow downward and
shoots grow upward. Anisotropic growth will continue even as a plant
is turned sideways or upside down. In other words, no matter what you
do to a plant within Earth's atmosphere, it will still grow roots down,
stem up. Growth can be positive or negative. Positive growth means
toward the stimulus and negative growth means moving away from the
stimulus. Geotropism was introduced as a term in the year 1869 by the
scientist A.B. Franck.
Plants kept inside a room always grow in the direction of the
window. In woodlands where there is a thick canopy of trees and
sunlight rarely falls on earth, very few plants survive. Those that do, do
not require sunlight to make their food. People have long wondered
about this phenomenon until the answer was discovered and explained
by the English naturalist Charles Darwin. He demonstrated that the
growing shoot of a grass seedling always bends towards light for
photosynthesis. This is due to a phenomenon called phototropism.
Without sunlight green plants cannot survive. How does a rigid plant
bend or grow to one side? Plant cells contain a substance called auxins.
This substance has a
tendency to move away from
the light. Auxins make the
cells on the darker side grow
faster than the cells on the
lighted side. This causes the
stems and the leaves to bend
or lean towards the lighted
side.
Materials: corn seeds, empty glass jar with lid, layer of nonabsorbent
cotton, paper towels, small amount of clay, water, Naturalist notebook,
and pencil
Name: ______________________Period: _____ Date: __________
EXIT TICKET – Plant Parts and the Nitrogen Cycle
What to do: Geotropism
1. Draw a data table like the one below and raw a sketch of the corn
seeds in the jar for day 1.
2. Each day that you come to class, observe and sketch changes that
you see in the seeds.
3. Make your observations for at least one week.
4. Write a summary of what happened over the course of the week in
your journal. Make sure to use the vocabulary that we are learning in
your summary.
Day
Day ___
Day ___
Day ___
Day ___
Diagram
What is
happening
1. Number the following steps (1-4) to show part of the nitrogen cycle.
________ Bacteria cause decay of animal waste, dead animals and
plants.
________ Plants absorb nitrates from the water in the soil.
________ Animals leave waste materials and other plants and animals
die.
________ Animals eat plants.
2. Which part of the root stores the excess food made by the plant and
the excess water taken in by the plant?
A. epidermis
C. central core
B. cortex
D. xylem
3. Match the following type of growth with the plant part during
phototropism.
_______Leaves
A. negative growth
Materials: picture, sandwich bag, paper towels, beans, water, staples,
naturalist notebook
_______Roots
B. positive growth
What to do: Phototropism
4. How is an animal’s response to stimuli different than plants?
1. Cut and glue the picture of the demo into your journal.
________________________________________________________
2. Next class you should draw on the picture what has happened.
5. Which scientist first introduced the term geotropism?
3. Look at the bags in the other locations.
4. Write a summary of what happened to the original bag and the other
bags during our experiment. Make sure to use the vocabulary.
A. Charles Darwin
C. Joseph Lister
B. Carolus von Linnaeus
D. A.B. Franck