topics 5,6,7,10,12 pbio exam

Meristem

Plant growth region of undifferentiated cells that divide often and make new tissues

Why meristems matter

Plants keep growing because meristems continuously produce new cells for organs and repair

Primary growth

Increases length of roots and shoots made by apical meristems

Secondary growth

Increases thickness in woody plants made by lateral meristems

Shoot apical meristem SAM

At the tip of shoots makes new stem tissue leaves and buds increases length

Root apical meristem RAM

At the tip of roots makes new root tissues increases root length

Apical meristems

Meristems at tips responsible for elongation and forming primary tissues

Lateral meristems

Meristems along sides that increase girth in stems and roots

Vascular cambium

Lateral meristem that produces secondary xylem to the inside and secondary phloem to the outside

Cork cambium

Lateral meristem that produces cork tissues forming outer bark for protection and reduced water loss

Differentiation

New meristem cells specialize into tissues like xylem phloem epidermis after division

Cell cycle

Interphase plus mitosis plus cytokinesis the full process of cell growth and division

Interphase

Cell grows and copies DNA includes G1 S G2 prepares for mitosis

Mitosis purpose

Produces two genetically identical daughter cells needed for growth at meristems and repair

Mitosis order

Prophase metaphase anaphase telophase in that sequence

Prophase

Chromosomes condense spindle forms nuclear envelope breaks down

Metaphase

Chromosomes line up at the cell equator attached to spindle fibers

Anaphase

Sister chromatids separate and move to opposite poles ensuring identical DNA sets

Telophase

Nuclear envelopes reform chromosomes decondense and two nuclei appear

Cytokinesis in plants

Cell plate forms between nuclei and becomes new plasma membrane and new cell wall

Vascular tissue

Transport system made of xylem and phloem connecting roots stems and leaves

Xylem function

Transports water and dissolved minerals from roots to leaves and provides structural support

Phloem function

Transports sugars mainly sucrose and other solutes to where they are needed

Source vs sink

Source exports sugars usually mature leaves sink uses or stores sugars roots fruits seeds growing tissues

Pressure flow hypothesis

Sucrose loading draws water into phloem raising pressure bulk flow moves sap to sinks then unloading lowers pressure