biology chapter 12 Flashcards
What are the main external features of a leaf?
Leaf blade, leaf stalk, network of veins
The leaf blade is the large flat surface, the leaf stalk holds the leaf away from the stem, and the network of veins carries water, mineral salts, and food.
What is the function of the veins in a leaf?
Carry water and mineral salts to cells; carry manufactured food to other parts of the plant
This dual function is crucial for maintaining the leaf’s health and supporting photosynthesis.
Describe the leaf blade.
Large flat surface, maximizes light absorption for photosynthesis, allows rapid diffusion of CO2
The structure of the leaf blade is essential for its role in photosynthesis.
What are the general arrangements of leaves on a stem?
In pairs (opposite) or singly (alternate)
This arrangement prevents leaves from blocking each other, ensuring adequate light exposure.
What is the function of the leaf stalk?
Holds the leaf blade away from the stem, ensures sufficient light and air reach the leaf
Some plants, like grasses, may lack a leaf stalk but have long leaf blades.
What is the upper epidermis of a leaf?
Single layer of closely packed cells, covered by a waxy, transparent cuticle
This structure helps protect the leaf while allowing light to penetrate.
What are the two types of mesophyll found in leaves?
Palisade mesophyll and spongy mesophyll
Palisade mesophyll is specialized for photosynthesis, while spongy mesophyll allows gas exchange.
What is the role of palisade mesophyll?
Contains numerous chloroplasts, specialized for photosynthesis
The palisade mesophyll’s structure optimizes light absorption.
What characterizes spongy mesophyll?
Irregularly shaped cells, large intercellular air spaces, fewer chloroplasts
This structure facilitates gas exchange within the leaf.
What is the function of the lower epidermis?
Single layer of closely packed cells beneath mesophyll
It contributes to the overall structure and protection of the leaf.
What is the function of the cuticle?
Reduces water loss
The cuticle is crucial for maintaining leaf hydration.
What are stomatal pores (stoma)?
Minute openings in the lower epidermis
They facilitate gas exchange by allowing CO2 in and O2 out.
What is the role of guard cells?
Regulate transpiration by controlling stoma opening/closing
Guard cells contain chlorophyll and are essential for maintaining water balance.
How does a waxy cuticle contribute to photosynthesis?
Reduces water loss; transparent for light entry
This adaptation is crucial for the leaf’s health and functionality.
What is the function of stomata during light?
Open to allow diffusion of CO2 in and O2 out
Stomata play a key role in the leaf’s ability to perform photosynthesis.
What is the significance of chloroplasts in mesophyll cells?
Absorb energy from light and transfer it to chemical energy in glucose
Chloroplasts are vital for the process of photosynthesis.
Why are there more chloroplasts in the upper palisade tissue?
For more light absorption near the upper leaf surface
This adaptation enhances the efficiency of photosynthesis.
What is the importance of interconnecting air spaces in spongy mesophyll?
Allow rapid diffusion of CO2 and O2 into and out of mesophyll cells
This structure supports efficient gas exchange.
What do xylem and phloem do in the leaf’s veins?
Xylem transports water/mineral salts; phloem transports food
This vascular system is essential for the leaf’s nutrition and function.
