Download Systems in Plants - RosedaleGrade10Science

SNC2D: Biology – Cells, Tissues and Systems
Tissues Working Together
(pp. 136-139)
A plant leaf is made up of a system of tissues, each with its own specific structure and function.
The structure and location of the tissues are connected to their function.
For photosynthesis, plants need to (1) absorb light, (2) obtain carbon dioxide and (3) obtain water.
Absorbing Light:
Leaves are green and thin –
Green – colour of chlorophyll, pigment that absorbs light for photosynthesis
Thin – wide and thin leaves have greater surface area for absorbing light
Chlorophyll is contained in the organelles called the chloroplasts.
Chloroplasts are located mostly in the ground tissue system, composed of the palisade layer and spongy
mesophyll.
Palisade layer – closely packed, located near upper surface to capture maximum light
Spongy mesophyll – loosely packed, permits gases to move around in the leaf
Obtaining Carbon Dioxide:
Cuticle – the layer of wax that covers the top and bottom surfaces of a leaf
This keeps the leaf from drying out since gases and water can’t pass through.
Stomata (singular – stomata) – tiny openings on the lower epidermis (lower leaf surface), allow gas
exchange and the release of water vapour.
Stomata are located on the lower surface to (1) reduce water loss, (2) provide more surface area for
photosynthesis, and (3) reduce chances of viruses, bacteria or fungal spores from entering the leaf.
Guard Cells - dermal cells that surround and control each stomata in a leaf
SNC2D: Biology – Cells, Tissues and Systems
Obtaining Water:
Water loss in a leaf is reduced by the waxy cuticle, and by closing the stomata when water levels are low.
Root hairs - absorb water from soil by osmosis.
Xylem and Phloem – vascular tissues arranged as bundles and run through the plant from root to leaf.
Water is transported by xylem from the roots, up the stem, through the leaves.
Comparing Plant and Animal Systems
Although plants and animals are very different organisms, there are some similarities at the cellular level,
as well as at the system level:
Cellular level:
Both animal and plant cells use sugar and oxygen in the process of respiration, and release carbon dioxide
and water.
System level:
Animals and plant cells both possess systems that must work together to accomplish complex tasks, in
particular, the fluid circulation systems.
Task
Obtaining food and transporting
it within the body
Animal organ systems
Nervous, musculoskeletal
systems are involved with
obtaining food
Plant tissue systems
Entry of carbon dioxide is
controlled by cells in the dermal
tissue system
Digestive system processes food
Ground tissue system in leaves
produces the plant’s own food
In the circulatory system, blood
vessels transport all digested
food nutrients
Vascular system transports
sugars and other complex
compounds in phloem.