321: Topic 1 - Growth Processes

What is growth?

An irreversible increase in size

What is elasticity?

The ability for somehting to go back to its original shape/size (NOT considered growth)

What two processes cause cell growth?

Cell division and cell elongation

What type of tissue does cell division and cell elongation occur?

Meristematic tissue

What is meristematic tissue?

Tissue that consists of cells that divide to produce more cells and is responsible for all growth

How does water affect cell growth and elasticity?

Water puts pressure on cell walls to expand a cell, but during periods of less available water, cells will shrink as water transpires

What is a shoot?

The stem and all appendages (leaves, reproductive structures, etc.) of a plant

What are the 3 major meristems?

Shoot apical meristems (forms buds), lateral meristems (widens the stem), and root apical meristems (lengthens roots)

What are lateral roots and how are they produced?

They are roots that grow out of another root, produced from deep within the parent root rather than the root apical meristem

What process causes vegetative growth?

Mitosis

What is cell expansion or elongation?

The expansion or growth of a cell due to hyrdrostatic pressure from water intake after the cell has split due to mitosis

What is cell maturation?

When newly expanded cells (after cell expansion/elongation) differentiate

Why are cell walls important in the cell growth process?

They contain lignin, which provides structural stability and have a high plasticity (ability to irreversibly change form)

What are the 3 parts of the cell wall?

The primary cell wall, secondary cell wall, and the middle lamella

What is the middle lamella?

The innermost section of the cell wall that is formed soonest after mitosis that glues the 2 new cells together

What is the secondary cell wall?

The part of the cell wall that is between the middle lemella and the primary cell wall

What is the primary cell wall?

The thin, flexible, and outermost layer of the cell wall that allows for growth by inserting itself into the middle lamella of two new cells and separating them

What is cellulose and what role does it play in the cell wall?

Primary structural and load bearing component

What role does hemicellulose play in the cell wall?

Provides structural rigidity and strength

What is lignin and what role does it play in the cell wall?

Strengthens and stiffens cell walls, allowing a plant to stand up straight

What role do proteins play in the cell wall?

Allows for cell enlargement, signal transfer between cells, and environmental response

What role do inorganic components play in the structure of the cell wall?

Forms cross-links between pectin molecules, which helps hold the components of the cell wall together

What is the role of pectin in the cell wall?

Binds plant cells together mainly in the middle lamella

What are buds?

Mini shoots enclosed by bud scales that contain leaf, bud, and often flower primordia

What are dormant buds?

Buds that remain inactive in growing until the spring when they open or "flush"

What is the bud arrangement for/how many buds do deciduous trees have?

Has terminal buds on each branch and axial buds for each leaf

What is the bud arrangement for/how many buds do coniferous trees have?

Has terminal buds on each branch but only some axial buds as there are too many needles to produce a bud per needle

Who all trees produce buds?

No (ex. Northern white cedar)

What is the function of long shoots?

Enlargement

What is the function of short shoots?

Growth of leaves and reproductive structures

What is a fascicle shoot?

A non-apical short shoot of a pine tree which produces a fascicle of needles and a group of bundle sheath scales below it

How many needles can fascicles contain?

2, 3, or 5 needles

What is the difference in the growht of needles between pine and spruce trees?

Pine trees produce fascicles shoots while spruce trees produce needles directly out of the long shoot (no short shoot required)