Leaves, Stem, and Roots

Question 1

Functions of leaves

Answer 1

-Main job is to perform photosynthesis(needs light, H2O, and CO2)
-Absorb energy in a organelle called a chloroplast which contains photopigments(chemicals which absorb specific wavelengths of light)
-Gas exchange: take in carbon dioxide and remove oxygen + water vapour
-Protection from herbivores

Question 2

Structured in Leaves

Answer 2

1: Veins
2: Petiole
3: Blade

Question 3

Veins

Answer 3

Vascular system in leaves and consist of
1.Xylem:
- hollow tubes with thick walls thay carry water
- Found in the outside parts of veins
2.Phloem:
-Carry food materials in solution from the leaves to other parts
-Inside part of vein

Question 4

Petiole

Answer 4

stalk connecting leaf to stem

Question 5

Blade

Answer 5

broad, flat portion of the leaf

Question 6

Internal structure of leaves

Answer 6

-Cuticle
-Mesophyll

Question 7

Cuticle

Answer 7

-waxy, waterproof layer on outer surface
-prevents water loss and provide physical layer of protection against bacteria, mould, and insects

Question 8

Epidermis

Answer 8

• outermost layer
• non-photosynthetic and transparent

Question 9

Mesophyll

Answer 9

-middle of leaf
-cells contain chloroplast; photosynthetic cells
-vascular bundles(veins) are embedded

Question 10

two types of cells in Mesophyll

Answer 10

-Palisade cells
* Layer of columnar cells just beneath the upper epidermis
* Most photosynthesis occurs here

-Spongy cells
*Layer of irregular shaped cells just above the lower epidermis
*Spaces between cells aid in gas exchange

Question 11

Other structures

Answer 11

Stomata: Adjustable pores which regulate the diffusion of CO2 and H2O

Guard cells: Pair of cells that regulate gas and water exchange with the air

Question 12

Leaf specializations

Answer 12

-Most plants use leaf specializations for protection
*Nicotine is produced by tabasco leaves to deter herbivores
* Cactus plants have spikes

-Some plants(gymnosperms) have chemicals which prevent their cells from freezing in the winter

Question 13

Human uses of leaves

Answer 13

-Nutrition
*Dark leafy greens contain minerals and vitamins
*Waxy cuticle can be used to make polishes for cars and furniture

-Toxins produced by leaves can be used to kill cancer cells(vincristine)

-Some leaves produce psychotropic chemicals meaning they alter the mind(marijuana leaves make THC)

Question 14

Functions of stems

Answer 14

-Support the leaves and reproductive structures
-Transport materials throughout the plant body
-Raise leaves to maximize exposure to sunlight
-Some store food

Question 15

Stem structures

Answer 15

1. Herbaceous stems
2. Woody stems

Question 16

Herbaceous stems

Answer 16

-contain soft, green, juicy tissues
-found in plants that live for less than two years

Question 17

Woody stems

Answer 17

-contain thick, tough tissue(wood)
-found in plants that live for more than 2 years(trees and shrubs)

Question 18

Herbaceous Stems

Answer 18

1.In monocots
*vascular bundles(xylem and phloem) scattered throughout the stem

2. In dicots
   *vascular bundles arranged in ring in cortex
   *vascular bundles consist of outer phloem and inner xylem

Question 19

Woody stems

Answer 19

-Can grow thicker due to vascular cambium(layer that divides to form xylem and phloem cells)

1) In monocots
*vascular bundles are scattered(palm tree)

2) In dicots
*annual rings are present
*result of new xylem produced each growing season(maple tree)

Question 20

Parts of Woody Stems

Answer 20

1. Pith: storage
2. Wood: support and transport of water(it’s the xylem)
3. Vascular cambium
   *produces xylem and phloem
   *responsible for increasing width
4. Bark: Consists of all of the tissues outside the vascular cambium(phloem, cork cambium, and cork)
5. Cork cambium is what produces cork
6. Cork- protection from environment

Question 21

human uses for stems

Answer 21

1. Fuel: wood and ethanol
2. Food: sugar cane, yams, asparagus
3. Dyes
4. Medicine: the pain relieve salicylic acid is made from bark
5. Textiles: flax is used to make linens, bamboo used in clothing

Question 22

Functions of roots

Answer 22

-Anchor plant: preventing erosion
-Support stem
-Absorb water and minerals from the soil
-Site of starch storage produced in leaves

Question 23

Types of Roots

Answer 23

Fibrous vs. Taproot

Question 24

Fibrous root system

Answer 24

• Fibrous root systems consist of a large number of branches, slender roots called lateral roots(monocot)
• Taproot systems consist of one large root (dicot) covered in little root hairs
  *Carrots, beets, turnips and radishes

Question 25

Roots specializations

Answer 25

-Most roots are made for efficiently absorbing water and nutrients, anchoring the plant and storing carbs
-To help absorb nutrients, plants have a mutualistic relationship with mycorrhizal fungi
*the fungi release digestive enzymes that break down organic matter which the plants can then absorb and in return the fungi receives carbs made by the plant
-Also have relationship with nitrogen fixing bacteria
*bacteria convert nitrogen from the air into a fork the plant can use
*the bacteria receives carbs made by the plant

Question 26

Human uses for roots

Answer 26

-Food
*many vegetables we eat are roots
-Drinks
*root beer was originally made from the sassafras plant root
*dyes
-Medicine
*kava kava root has been shown to to reduce anxiety
*valerian root can be used to relieve insomnia

Question 27

There are 2 parts of mesophyll

Answer 27

-Palisade mesophyll
-Spongy mesophyll