Biology-Mr. Willets
Roots / Leaves / Other Info
The root of a plant has 4 functions. First, roots anchor the plant firmly in the soil. The taller the plant is, the firmer this anchor must be. Willow tree roots do not go as deep as other trees which makes it easier for a storm to blow the willow over.
The second function of roots is to absorb water and minerals from the soil. To more effectively do this, there are many tiny extensions near the ends of the root. These are called root hairs. If you wish to move a plant successfully, you must make sure that you dig up enough of these root ends with root hairs. If all you dig up are the large woody sections of the roots, then the plant may not be able to absorb enough water to survive.
The third function is to transport the water and minerals up the plant. To do this, the root has vascular tissue.
The fourth function is storage of food and/or water. Many roots store food. Carrots, beets, radishes are all examples of roots that store food. The sugar made by maple trees during the summer is stored in the roots. In the spring, this sugar is sent up to the top of the tree and used to grow new leaves. We "steal" some of it as it goes up when we tap into the tree.
If a plant has one main root with few lateral (side) roots, that one root is called a tap root. A carrot is a tap root.
If a plant has no main root but many intertwined lateral roots, they are called fibrous roots. The grass in your lawn has these. Fibrous roots help hold the soil together. If you have ever removed some grass from an area, you are aware of this. In California, there are occasional mud-slides. These often occur in areas where grass fires have destroyed the fibrous root system and the soil is easily moved by the rains.
Some plants have roots that grow from the sides of stems and leaves. These are called adventitious roots. Ivy uses these to attach to walls. Certain orchids that grow attached to tree branches have air roots (these can absorb water from the very humid air in the rain forest and get minerals from dust in the air)
When you grow corn, it is a good idea to put some dirt around the base of the stem. This encourages roots to grow from the side. These are called prop roots and help support the top heavy corn stalks.
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The function of leaves, with a few exceptions, is to make food. To do this, they need light and are therefore located as high as possible. They need water which is brought up from the roots. The water gets to the cells of the leaf through the veins. They need carbon dioxide which enters through openings (stoma) usually in the lower layer of cells (lower epidermis). Needles are leaves designed to lose less water.
The main part of the leaf is called the blade. The blade is attached to the stem by a petiole. You would probably call the petiole the "stem" of the leaf (but you would be wrong!)
The leaves of monocots have parallel veins. The leaves of dicots have net veins. The actual shape of the leaf varies greatly and can be used to identify a specific type of plant. A three-leaf clover (or a four-leaf clover) has actually only one leaf that is divided into 3 leaflets. Such a leaf is called a compound leaf.
A tree that loses it leaves all within a short time is called a deciduous tree. The process of the leaf separating from the tree is called abscission.
Some leaves have been modified for special uses. The tendrils of a pea plant are leaves that can grab onto a support structure like a pole. Insectivore plants have leaves that can capture insects. The cactus spines are leaves designed for protection. The stem of the cactus is where photosynthesis actually occurs.
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Many plants "know" what season it is by the length of daylight compared to night. This is called the photoperiod. A short-day plant will bloom in the spring or fall. A long-day plant will bloom in the summer.
A tropism is a plant movement in response to something in the environment. Hydrotropism is a response to water. Phototropism is a response to light. Gravitotropism is a response to gravity. A positive tropism means the plants moves towards the stimulus. A negative tropism means it moves away.
Biology - Mr. Willets
Questions-Roots/Leaves
1) The four functions of roots are a) _____________________ the plant b) absorb _____________
________________________c) __________________________________________
d) Storing ____________________________
2) Deep roots would be a good ___________________ for a tree. They also might be able to get to ___________ that is deeper down. (think about it)
3) If you dig up a plant and only get the large roots, why might the plant not survive if replanted?
_____________________________________________________________________________
4) Name some roots that store food that we eat. ____________________________________________
5) If a plant has one large root, the root is called a __________________Give an example____________
6) Grass has what type of root system? _________________________ Often we plant grass to prevent the loss of ________________.
7) Why would prop roots help a plant such as corn? ________________________________________
8) Adventitious roots often grow from the sides of _______________.
9) Certain orchids have __________ roots. They can only live where the air is very ______________
10) The veins of a leaf would have what tissue in them?(think about it) __________________________
11) Parallel veins would indicate that the plant is a ___________________ The other type of venation (vein pattern) is called ___________________________
12) Carbon dioxide enters a leaf through the stoma. What exits through these openings? ______________
13) When does abscission occur for a deciduous tree? _____________________
14) What is incorrect about the name "4 leaf clover"? ______________________________________
15) Pole beans are called that because they grow best when given a pole to grow on. What connects them to the pole? ___________________________ This is modified type of ___________.
16) A long-day plant will bloom in the ______________________. This is because the amount of light compared to dark is ___________. This comparison of light to dark is called ______________________
17) Besides temperature, what else would you change in a greenhouse to make a plant bloom in February? ____________________________________________________________________________
18) Any movement a plant makes in response to something in the environment is called a ______________.
19) Describe what positive phototropism means.___________________________________________ What could you do with a house plant to demonstrate this? ____________________________________
20) What part of a plant would exhibit negative gravitotropism? _______________________
21) What part of a plant would exhibit positive gravitotropism? _______________________