All of SB6 Flashcards
(42 cards)
Starch is stored in tubers in an organelle called?
Amyloplast
What is ecology?
Study of ecosystems by observing interactions between organisms and their environment
Internal factors that affect rate of photosynthesis?
Number of stomata (greater diffusion of gases)
Size and distribution of intercellular space (greater storage for gases)
Age of leaf (younger; faster)
Amount of chlorophyll present
During dark reaction of photosynthesis, what are the products?
C02 and H20 (affected by temperature)
During light reaction of photosynthesis, what are the products?
H20 molecule split into 02 (affected by light intensity)
External factors that affect photosynthesis
Light intensity
Temperature
Water levels
Mineral elements
How does light intensity affect photosynthesis
Light intensity (greater light intensity; light reaction favored; more H20 into 02; greater rate of photosynthesis) (stomata also open more)
How does temperature affect photosynthesis
Rate of photosynthesis increases as temp. does, increased collisions (enzyme activity favored)
How does C02 concentration affect photosynthesis
C02 conc. (increases; dark reaction favored; more carb.)
How does amount of water affect photosynthesis?
Water (lack of which; guard cells flaccid; stomata unable to open; C02 absorption hampered; wilted leaves; photosynthesis hampered)
How do mineral elements affect photosynthesis?
They are components of photosynthetic enzymes; deficiency affects synthesis of photosynthetic enzymes
Why does active transport occur in the root hair cells?
The concentration of minerals in the root hair cell is greater than in the soil.
Minerals move into the cell against the concentration gradient.
Therefore high rate of metabolic reactions; sugars must be transported to the tissue
What helps prevent the roots from being pulled out of the soil (by wind etc.)
Xylem vessels; mechanically strong and grouped together at the center of the root
Within the vascular bundles, the phloem vessels are located around the edge of the stem, with xylem closer to centre why is this?
Stem is able to withstand bending caused by the wind.
In the leaf, where is the xylem and phloem located?
Xylem is located on the upper part of the vascular bundle, whereas phloem; lower part.
Where does photosynthesis mainly take place in the leaf?
Palisade mesophyll; upper part of the leaf.
Purpose of lignin in cell walls of xylem vessel?
Helps; support the structure of xylem vessel
When water is pulled up the vessels, it causes pressure to fall slightly, lignin prevents vessels from collapsing
What does the xylem consist of?
Xylem consists of xylem vessels and xylem fibres.
Xylem fibres provide mechanical support for the plant; no transportation of water. Xylem fibres have high amounts of lignin present.
Parenchyma cells.
Purpose of parenchyma cells in xylem?
Parenchyma cells act as a store of starch;
can contain tannins, bitter compounds released to deter herbivores
During photosynthesis; glucose produced. This is used to create other compounds known as?
Assimilates
Job of xylem?
Carry water and dissolved mineral ions from roots to the leaves
Job of Phloem?
Transport assimilates from the leaves to other parts of the plant.
(Phloem sap can be transported up and down the leaves)
What two cells does the phloem consist of?
Sieve tube element cell and Companion cell
Describe the structure of the sieve tube element cell
Endwalls of cell; sieve plate
Sieve plate; large pores present; allow phloem sap to move between the cells
