Test 2 Flashcards
Lectures 3 & 4 (94 cards)
Why are plants important?
- Plants supply food.
- Plants maintain the atmosphere.
- produce oxygen and absorb carbon dioxide during photosynthesis
- oxygen is essential for cellular respiration for all aerobic organisms
- maintains the ozone layer that helps protect Earth’s life from damaging UV radiation
- removal of carbon dioxide from the atmosphere reduces the greenhouse effect and global warming - Plants recycle matter in biochemical cycles.
- plants such as pea’s host on bacteria that fix nitrogen
- this makes nitrogen available to all plants, which pass it on to consumers - Plants provide many products.
- Plants create habitats for many organisms.
What is the environment and conditions of a shoot system?
Environment - above ground, thin, gaseous
Conditions - low water, fluctuating light, wind, heat, UV exposure
What is the environment and conditions of a root system?
Environment - below ground, dense, soil based
Conditions - water often available, patchy resources, many pathogens
What is determinate growth?
Determine Growth
- growth with defined limits
- occurs in most animals and some plant organs eg. most leaves
- growth stops once a certain size is reached
What is indeterminate growth?
Indeterminate Growth
- no defined growth limit
- continuous growth throughout a plant’s life (except during dormancy)
- plant has embryonic, developing, and mature organs at all times
What is a meristem and what is its function?
Meristem
- perpetually embryonic tissues in plants
- enable indeterminate growth
- sites for new cell formation, growth and differentiation
Where are apical meristems found?
At tips (apices) of shoots and roots.
What are apical meristems responsible for?
Primary growth - lengthening of the plant
What does the lateral meristem consist of?
The vascular cambium and cork cambium.
What are lateral meristems responsible for?
Secondary growth - thickening of stems and roots.
- present in all gymnosperms and most eudicots
- rare in monocots
What is the first step of cell division for meristems?
Step 1: One meristem cell divides, producing……
- one differentiated cell (which will develop into specialised tissue)
- one remaining meristem cell (to continue dividing)
What is the second step of cell division for meristems?
Step 2 and Beyond: this process continues, with each cell division producing a new differentiated cell and maintaining the population of meristem cells
What protection features are in place to protect apical meristems?
Apical meristems can be dormant in buds, which is important if the Shoot Apical Meristems (SAM) gets damaged or eaten.
What is the leaf primordia?
Protects the shoot apical meristem.
What is the root cap?
Protects the root apical meristem.
What is the vascular cambium?
Produces secondary xylem - the main component of wood.
What is the cork cambium?
Produces the outer bark.
What is dermal tissue?
- outer protective covering, known as the epidermis
- usually one cell layer thick
What are epidermal cells?
- main cells in the epidermis
- transparent, most lack chloroplasts
What are guard cells responsible for?
- regulating the opening and closing of stomata
- present shaped, contain many chloroplasts
What are palisade mesophyll?
Photosynthetic cells found just below the epidermis (in leaves).
What are spongy mesophyll?
Cells involved in gas exchange (in leaves).
What are trichomes?
- hair-like structures that grow from the epidermis to protect or aid in water retention
- cool leaf surfaces and reduce evaporation
- cover stomatal openings to limit water loss
- some are glandular and secret substances to deter herbivory
What are root hairs responsible for?
- increase root surface area for water and nutrient absorption
- may be covered by a fatty cuticle (a waxy coating) in some plants to reduce water loss