Chapter 9, Transport in Plants

9.1 The Transport Structures of Flowering Plants

 

Transport / Vascular tissues in Plants: ___________________________________

 

 

 

 

 

 

 

 

 

Xylem

Structure:

n   Consists of many xylem vessels that are long and hollow, stretching from

______________________________.

n   Made up of ________________.

n   The inner wall is strengthened by a hard substance called ___________ that is deposited on it.

 

Different patterns of lignification

 

 

 

 

 

 

 

 

Functions of xylem

n   Conducts ______________________________ from the roots to the stems and leaves.

n   Provides _______________________________ for the plant.

 

Adaptations

n   A continuous lumen without any _________________________to prevent the flow of water and mineral salts.

n   Walls are lignified to prevent the _____________________________________.

Phloem

Structure:

n   Consists of _____________________________.

n   A sieve tube consists of columns of elongated, thin-walled living cells called the _____________________________.

n   Cross-walls separating the cells are perforated by minute pores like a sieve called ________________________.

n   Matured sieve tube cells do not have vacuole, organelles and nucleus, except a thin later of cytoplasm.

n   Substances are transported by __________________________________.

 

Companion cell

n   It accompanies each sieve tube cell.

n   It is a narrow, thin-walled cell with many ______________________________.

n   It ______________________________________________________________.

 

Functions of phloem

n   Transport _____________________________________________ from the leaves to other parts of the plant.

 

Adaptations

n   The sieve plates are perforated to enable food substances to pass through them to be transported to various parts of the plant.

n   Companion cells have many mitochondria to ____________________________

________________________________________________________________.

 

Differences

 

Xylem	Phloem

 

Organization of vascular tissues in stems

Vascular bundles in roots

Cross-section of a dicotyledonous root

 

 

Organization of vascular tissues in roots

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.2 Studying the Movement of Substances in Plants

 

Translocation in plants

n   Transport of _______________________________________________.

n   Occurs in the _____________.

	1.  Sugars formed in leaf cells are ___________________ by companion cells (loaded) into phloem.   2.  Bulk flow of water pushes sap to sinks.  Sink cells actively remove ________, and convert them to ________.  Water is recycled through xylem.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Using aphids in translocation studies

Aphids are insects which feed on plant juices. They penetrate phloem tissue with their ______________. Aphids are anaesthetized with __________________ while feeding. The body is cut off, leaving the proboscis in phloem.

 

Using isotopes in translocation studies

Providing a leaf with __________________________ .

Stem is cut off, and a section is exposed onto an X-ray photographic film.

Results: ______________________________________________________________.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.3 Entry of Water into a Plant

 

 

 

Entry of water through the roots

n   This takes place at the ____________________.

n   Root hair grows between the soil particles with close contact with water.

n   Mineral salts are dissolved in soil water.

n   Sap of root hair cells has a __________________________________________.

n   Since the surrounding soil particles have a high water potential, water from the soil ___________________________________.

 

 

 

Adaptations of the root hair cell to absorption

1. _____________________________________

n  Increases surface area to volume ratio;

n  Increases the ______________________ of water and mineral salts.

2.  _____________________________________

n  Water enters root hair cell by osmosis.

3. _____________________________________

n  Generates energy from cellular respiration;

n  ______________________ can take place.

 

9.4 Moving Water against Gravity

 

Entry of water up the stem by:

_________________________

n   By using active transport, ions in the living cells ________________________ in the root are pumped into the vessels.

n   Water potential in the xylem vessels is _______________.

n   Water passes from the living cells into the xylem vessels by osmosis and flows upwards.

 

_________________________

n   Water moves up inside fine capillary tube by ____________________.

n   Water molecules attract other water molecules by ________________________.

n   Water sticks to the upper inner surface of the xylem vessels by _____________.

n   The water moves up the plant into the leaves.

 

________________________

n   Transpiration is the ______________________________________________, especially through the stomata of the leaves.

n   The suction force caused by transpiration is called ______________________. It is the main factor that causes the movement of water up the xylem.

 

Importance of transpiration

n   Transpiration pull draws __________________________ from the roots to the stems and leaves.

n   Evaporation of water from the cells in the leaves removes _______________________________. This cools the plant, preventing it from being scorched by the hot sun.

n   Water transported to the leaves can be used in photosynthesis to _______________________________. Turgid cells keep the leaves spread out widely to trap sunlight for photosynthesis.

 

Potometer

n   Instrument that can be used to _______________________________.

 

 

 

 

 

 

 

Factors affecting the rate of transpiration

n   ______________________

A rise in the temperature of the surroundings increases the ___________________, thus increasing the rate of transpiration.

 

n   ______________________

Air inside leaf is saturated with water vapour

Increasing the humidity of the air will _____________________________________ between the leaf and the atmosphere, therefore decreasing the rate of transpiration. When the atmosphere’s humidity decreases, the rate of transpiration increases.

 

Adaptations of plants living in dry conditions

1.            __________________________ to reduce surface area exposed to evaporation

2.            __________________________

3.            Reduction in the number of ______________

4.            ______________________ to trap pockets of moist air around it.

 

n   _____________________

When light intensity is increases, stomata open, increasing the rate of transpiration. When light intensity is reduced, stomata close. An increase in light intensity ____________________________________.

 

n   _____________________

Blows water vapour away at the surface of leaves. Maintains _________________________________ between the leaf and the atmosphere. The stronger the wind, the faster the rate of transpiration. When the air is still, transpiration reduces or stops. Rapid transpiration occurs under __________________.

 

Wilting

n   The turgor pressure in the leaf mesophyll cells helps to ___________________ and __________________________ to absorb sunlight for photosynthesis.

n   In strong sunlight, when the __________________________ exceeds the rate of absorption of water by the roots, the cells lose their turgor, become flaccid and the plant wilts.

n   Wilting also occurs in the soft stems of certain plants in which the stem mesophyll cells lose water.

 

 

 

 

Advantages of Wilting

n   When the leaf folds up, the surface area that is exposed to sunlight is reduced, causing the ____________________________________.

n   ______________________ and the rate of transpiration is decreased.

 

Disadvantages of Wilting

n   The rate of photosynthesis is reduced because ___________________________.

n   As the stomata close, the amount of _____________________________ is also reduced. Carbon dioxide becomes a limiting factor, thereby decreasing the rate of photosynthesis.