Plant Organs Flashcards
what are the plant organs?
Stems
Roots
Leaves
what root systems do monocots vs dicots have
monocots = fibrous root system dicots = taproot system (usually)
What is the main different between monocots and dicots?
monocots have one cotyledon embryo
Dicots have two
what difference is there in monocot vs dicot leaves?
Monocots = veins are usually parallel Dicots = veins usually net-like
what difference are there in monocot vs dicot stems?
Vascular bundles
Monocots = complexly arranged bundles
Dicots = arranged in a ring (usually)
what difference are there in monocot vs dicot flowers?
Monocots = floral parts in multiples of 3 dicots = floral parts in multiples of four or five
what is the difference between primary and secondary roots?
primary grow downwards
secondary branch outwards
what are the 4 main types of root systems?
Taproot
Fibrous
Prop/ adventitious
Ariel
What are the 3 main functions of roots?
absorb minerals and water from soil
anchor and support plant
store food made from photosynthesis
What is the tip of the root called?
root cap
What is the function of the root cap?
regulate primary growth of root through specialised meristem cells
what kind of cells cover the root
a single layer of epidermal cells = epidermis
what tissue is found beneath the epidermis of the roots?
ground tissue
what type of tissue is found in the centre of roots?
vascular tissue
what adaptation makes root vascular tissue efficient carriers for water and minerals?
they have a waxy layer to prevent leakage
how many layers of epidermal cells make up the epidermis of the stem?
1
what replaces the epidermis of trees?
bark
what are the 3 main functions of stem?
to hold up leaves (for photosynthesis)
transport water and nutrients from roots to leaves
storage (only in some plants)
Structural support
How does the phloem translocate sugar?
Pressure-flow hypothesis and turgid cell pressure
when is stomata most open?
midday
what are the 6 structural parts of the stem?
Node - where leaves attach
Internode - stem between nodes
Rhizome - horizontal underground stem
Tuber - underground stem for food storage
Bulb - large bud with layers for food storage
Corm - upright thickened underground stem
what are very thick, specialised stems good for? Give an example
Storing lots of food and water - i.e: Australian baobab tree can store up to 120,000 L of water in trunk
what are specialised vine stems good for?
clinging and climbing - have thicker, threadlike tendrils at ends to twine and grip surfaces e.g: devil’s ivy
what are woody tree trunks specialised for?
strength and support - can grow very tall
what are rhizomes specialised for? Give an example
vegetative asexual reproduction - have horizontal underground stems
i.e: ginger, flag iris
What are thorns specialised for?
Protection from herbivores
what does the phloem move?
sugars mainly
What does the xylem move?
water and nutrients
which type of meristem causes stem length growth?
apical meristems
which type of meristem causes stem girth growth?
lateral meristems
What is bark made from?
Cork from cork cambium and phloem
How does the pressure-flow hypothesis work?
- Sugar is loaded into sieve tube elements at source (usually leaves) by active transport
- Water from xylem follows sugar into sieve tube element via osmosis
- Creates high turgor pressure in phloem, forcing sugar and fluid to the sink (the root)
- Sugar leaves phloem via active transport and water leaves via osmosis
What is transpiration?
The process of water movement through a plant and its evaporation
What is translocation?
the movement of materials from leaves to other tissues throughout the plant
According to the cohesion-tension theory, what is the main driver of water movement in the xylem?
Transpiration
