chapter 37 test your understanding, knowledge, PS

Compare and contrast the roles of parenchyma cells in the ground tissue system versus the vascular tissue system

Parenchyma cells in the ground tissue perform photosynthesis and/or synthesize and store materials. In vascular tissue, parenchyma cells in rays conduct water and solutes across the stem; other parenchyma cells differentiate into the sieve-tube elements and companion cells in phloem.

Explain why continuous growth enhances the phenomenon known as phenotypic plasticity

it allows plants to grow and respond to changes or challenges in their environ- ment (such as changes in light and water availability).

Which one of the following tissues is most likely to be the source of nutrition for insects that kill trees?

vascular cambium

Identify the structure you are consuming when you eat each of the following vegetables: asparagus, Brussels sprouts, celery, spinach, carrot, potato.

Asparagus—stem; Brussels sprouts—lateral buds; celery—petiole; spinach—leaf (petiole and blade); carrots—taproot; potato—modified stem

Describe how the vascular cambium produces secondary xylem and secondary phloem.

Cells produced to the inside of the vascular cambium differentiate into secondary xylem; cells produced to the outside of the vascular cambium differentiate into secondary phloem.

Compare and contrast the structure and function of collenchyma and sclerenchyma cells

Collenchyma and sclerenchyma cells both have thickened cell walls and function in provid- ing structural support. Unlike collenchyma cells, scle- renchyma cells have lignified cell walls and are dead at maturity

What does cuticle do? What do stomata do? Predict how the thickness of cuticle and the number of stomata differ in plants from wet habitats versus dry habitats.

Cuticle reduces water loss; stomata facilitate gas exchange. Plants from wet habitats should have a rela- tively large number of stomata and thin cuticle. Plants living in dry habitats should have relatively few stomata and thick cuticle

Trees can be killed by girdling—meaning the removal of bark and vascular cambium in a ring all the way around the tree. Explain why.

Girdling disrupts transport of solutes in secondary phloem. The tree's root system starves.

How do tracheids differ from vessel elements, in addition to their overall shape?

In tracheids, water flows from cell to cell primarily through gaps in the secondary cell wall called pits.

Which statement best characterizes primary growth?

It produces the dermal, ground, and vascular tissues.

Which statement best characterizes secondary growth?

It results from divisions of the vascular and cork cambium cells.

Describe the general function of the shoot system and the general function of the root system. Which tissues are continuous throughout these two systems? Suggest a hypothesis to explain why the shoot and root systems of different species are so variable in size and shape.

The general function of both sys- tems is to acquire resources: The shoot system captures light and carbon dioxide; the root system absorbs water and nutrients. Vascular tissue is continuous throughout both the shoot and root systems. Diversity in roots and shoots enables plants of different species to live together in the same environment without directly competing for resources.

Why do mahogany trees, and other trees that grow in tropical rain forests, lack growth rings?

They grow continuously, so do not have alternating groups of large and small cells that form rings.

5. To illustrate the concept that a plant structure can be modified for many different functions, give an example of a leaf and a stem that protect individuals against large herbivores.

cactus spikes, thorns

Which of the following functions is not performed by parenchyma cells?

provide mechanical support

What is a sieve-tube element?

the sugar-conducting cell found in phloem