Biology 2601A/B Lecture Notes - Surface Tension, Lignin, Aquaporin

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amaranthporcupine481

10 Dec 2012

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Xylem is most often referred to as the water-transporting tissue in plants as it translocates water and inorganic nutrients (like nitrogen, phosphorous and potassium) from the roots to the leaves. The other component of vascular transport in plants is phloem whose main function is to translocate sugars, proteins and signalling molecules from source tissues (like the leaves) to sink tissues (like the roots). Xylem is composed of tracheids (long, thin cells) and vessel elements (short, wide cells) that share some key differences. Both of these cells are classified as dead cells that only act as pipes to transport water. Water moves between the tracheids only through pits, while between vessel elements water moves mostly through perforation plates (compound or simple) and subsidiary flow through pits. The xylem is supported by fibres and other lignified cells (especially the case for trees) to ensure stability. Vessel elements are the primary vessel type in angiosperms (broad-leafed plant species), which also contain tracheids.

Related Questions

Question 1: A slide of a terminal plant bud shows what physical characteristics demonstrating growth?

Answers:

1. an actively dividing group of cells between primordial leaves with undifferentiated vascular tissue

2. a vascular system with vascular bundles

3. spongy mesophyll tissue

4. sieve tubes, vessel elements and tracheids

Question 2: As the earth warmed and dried around 150 MYA, plants requiring _______ for fertilization were no longer dominant, but were eclipsed by plants that were ______ bearing named ___________ (literally naked seeds). These plants used _____ for fertilization freeing themselves from dependence on water. As animals of the era became terrestrial with means of terrestrial reproduction strategies, plants did the same using two different structures along with internal fertilization, the _____ being internal and fertilized by a wind carried _________ grain.

Answers:

1. water, seed, charophytya, dinosaurs, zygote, pollen

2. water, seed, gymnosperms, wind, egg, pollen

3. spores, cone, tracheids, water, pollen, embryo

4. water, flower, angiosperms, animals, spore, egg

Question 3: In the pith region of a stem the vascular system consists of two major structures;

Answers:	1. Phloem with trachieds and vessel elements and xylem with sieve-tubes and companion cells
	2. Sclerechyma fibers and parenchyma cells
	3. Phloem carrying photosynthesis products and xylem carrying water with dissolved nutrients
	4. Phloem carrying water with dissolved nutrients and xylem carrying photosynthesis products.

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11. As energy flows through the food web in an ecosystem, the amount of energy that is transferred from one trophic level to the next trophic level increases. stays the same. decreases. may increase or decrease, depending upon the system.

12. Autotrophs are organisms that obtain energy by breaking down tissues of organisms that have died. harness external energy sources to produce complex chemical compounds. depend directly on primary producers for their energy and nutrients. eat other autotrophs to obtain energy.

13. Which of the following gives the correct order for energy flow through an ecosystem? primary producers â secondary producers â tertiary producers primary consumers â primary producers â secondary producers secondary consumers â primary consumers â primary producers primary producers â primary consumers â secondary consumers

14. Which one of the following aspects of plant biology is not directly involved in maintaining an adequate supply of water for the entire plant? phloem roots xylem transpiration pull

15. Which structure(s) do most plants use to acquire the energy that they need for cellular processes? the roots the leaves the stem

1. What protects the leaf against desiccation and stress from other environmental factors? Select one: a. Stomata b. Mesophyll c. Epidermis d. Cuticle

2. Match the monocot stem terms to their definitions.

a) support the stem structurally and are dead fibrous cells that have thick walls

Answer choices: Parenchyma Phloem Sclerenchyma Xylem

b) transport water and nutrients up from the roots

c) characterized by large vacuoles, which store nutrients and food.

d) transport sugar formed in the leaves by photosynthesis to the rest of the plant to be used as food.

3. Match the eudicot stem terms to their definitions.

a)surrounds and protects the vascular bundle	Answer choices: Parenchyma Collenchyma Pericycle Cambium Pith
b)center portion of the stem
c) located underneath the collenchyma
d) strengthen young stems and synthesize food
e) contains cells that divide to produce new xylem and phloem

4. Suppose you chop down a plant in the woods and bring it home to examine. You cut a cross section of the stem and you note that it has pith in the center. How would you classify this plant?

5. You encounter a shrubby-looking plant that you cannot tell if it has true wood or not. Upon cutting it open cross-sectionally, you note a layer of cork cambium. What does this tell you?

Biology 2601A/B Lecture Notes - Surface Tension, Lignin, Aquaporin

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