Friday, December 6, 2013

More Plants! Warm up 2


Compare growth due to apical and lateral meristems in dicots

Growth in plants is brought about initially with cell division at the apical and lateral meristem.

Observation of shoot/root tips with light microscope reveals regions with cell in the various stages of mitosis. (Cell division, reproduction)  

This growth process adds length to the stem or root

Secondary growth added by the Lateral meristem has two types

1.       Vascular cambium that produces secondary xylem and phloem

2.       Cork cambium produces some of the bark layer of the stem

Explain the role of Auxin in phototropism

If light is scares because an area is crowded with plants or for some other reason, a plant needs to grow towards the light so it can get as much of it as possible.

Auxins are plant hormones that cause positive phototropism of the plant shoot and seedings

Explain how water us carried by transpiration stream, including the structure if xylem vessels, traspirational pull, cohesion, adhesion and evaporation

Plants!!! Warm up


Outline the differences (5) between the monocots and dicots

Feature
Monocots
Dicots
Venation
Parallel venation
Net- like venation
Number of Cotyledons
Two
One
Floral Organs
Petals in multiples of three
Petals in multiple of 4 & 5
Roots
Fibrous adventitious
Tap root with branching laterals
Leaf Mesophyll
Spongy
Palisade and spongy
Vascular Bundle Arrangement
Arranged in rings. Divided into cortex and stele
Bundle, no particular order

Identify and describe modifications of roots, stems, and leaves of different plants. Give one example of each
Stem modification

Bulbs: Onions and lilies

·         Short vertical underground stems

·         Many fleshy highly modified leaves for the storage or nutrients

·       Can produce new plants by bulb division or development of one of the many auxiliary buds

Horizontal stems- runners

·         Spread out from the main body of the plant

·         At the point the stem touches the ground, a new root forms

·         Asexual reproduction, if a runner id broken it can establish its self as its own plant

·         Adaptation for finding water

Cacti

·         Leaves are reduced to spines to prevent water loss in transpiration

·         The stem is enlarges for storage of water

·         The stem carries out photosynthesis

Root tip modification

 Tuber/ Potato 

·         The potato is an underground modification of the root tip

·         The ‘eaten potato’ contains the carbohydrate and protein stores for the growth

·         Auxiliary buds

Tap Root modification

·         Function: Storage of water

·         Sandy soils