plant structure Flashcards
key functions of root
acquisition of water and mineral
anchor plant
what are the key functions of stem
transport- against gravity
transport water and minerals up xylem
sugars down phloem
create rigid structure
key features of leaf
photosynthesise
gaseous exchange
adaptations of cactii
Stem has adapted into photosynthesising surface and leaves have become needles for defence, rather than surfaces with large areas and lose water through transpiration
root system of a monocot
Monocot has fibrous roots, a large surface area for maximum uptake of water and minerals, no need to store sugars as these species will generally self seed in 1 year
root system of a eudicot
taproots are a storage system that maintains a sugar supply throughout the year which the plant can draw on to put on new stem and leaf growth the following spring
(corms, tubers and rhizomes are stem adaptations that perform the same function in both monocot and eudicot they are called perennating organs)
epidermis surface layer of plant
protection from pests- Urtica dioica (hair is a tube filled with chemical cocktail that stings)
hairs- stop pests feeding, can help with water retention as they trap air next to the leaf,
waxy- retain moisture and stop evaporation and protect internal tissues
cambium
growth layer
a layer of partially undifferentiated cells, to allow for secondary growth or thickening of stem, or growth at root and shoot
between xylem and phloem
massive amount of cell production in these areas
parenchyma
storage cells, create bulk for support storage of essential nutrients -sugars and water
rigidity
this is the mesophyll and pith of plant
where is apical/ lateral meristem
in the cambium tissue found in the buds and growing tips of roots
triggers the growth of new cells
lateral meristemic tissue is responsible for thickening stem of plant
examples of root adaptations
Hydreangea petiolaris- adapted roots for climbing
Ficus benjamina- a strangler fig, sticky seed lands on a tree host, puts long roots down until it ouches soil and then produces foliage that outcompetes tree host. Can also protect host form weather as it creates more anchorage
Nitrogen fixing nodules in pea and bean plants
Zea mays (Sweetcorn)- prop roots for anchorage, lateral roots grown sideways
key parts of root tissues
root hair cell comprises
epidermis xylem phloem cambrium and ENDODERMIS
key parts of stem tissue
epidermis xylem phloem cambium
Key parts of a leaf
veins are important for transport in leaf
epidermis
LAMINA stretchy flat surface that collects light- blade of the leaf
palisade mesophyll (chloroplasts)
spongy mesophyll (air spaces)
xylem phloem
stomata (incl. guard cells)
a plant cell
cell walls from cellulouse create rigidity and protection
cytoplasm
organelles including vacuole
chloroplasts
mitochondria
nucleus
ribosomes
entire and serrate
dentate
Key reasons for flowers on plants
attract pollinator with colour and scent
reproductive organs within
seeds produced in an ovary and ‘fruit’ (including rice, nut, maple etc)
Benefit of sexual reproduction/
Cross pollination
Mitosis or myosis?
Genetic variation is the key to evolution
Diversity from two parents, changes genetic coding of seeds
MYOSIS
pollen grain shapes
wind dispersal v. flower pollens
Wind dispersal
smoother (aerodynamic)
millions produced
smaller pollen grains
Flower pollens
often stickier/ textured surface
less pollen grains produced
larger pollen grains
pollen produced in anther at top of filament- this structure is called the stamen
stigma is the area at the top of the style which leads down to the ovule- this whole structure is called the pistil
stem is penduncle, between ovule and peduncle is receptacle
Monecious plants
plants have both male and female parts on one plant, they may be in different places, or occur at different times (to stop self seeding)
e.g Coryllus avallana pollen catkins and little alien flowers of bare stigmas
Dioecious plants
each plant has either male or female reproductive organs
e.g. Ilex aquifolium- holly, only the female plant will bear berries and only of it has been fertilised by a nearby male plant
hermaphrodite plants
plants with both pistil (female organs) and stamen (male organs) in the same flower.
Vanilla planifolia
Vanilla flower which is hand pollinated as pollination must occur in 6 hour window for best success and the bee that usually pollinates it is so rare.
Stem adaptation examples
-Protection e.g the thorns of Cretaceous monogyna plants in the Rosa genus thorns
-storage e.g perennial plants with tubers, corms and rhizomes Cyclamen hederifolium
-climbing Hedera helix hairs along stem
Leaf adaptations and examples
Hairs
Leaf hairs - Galium aperine to climb and stick to Animals and clothes, leaf hairs on underside of leaf maintain a higher level of humidity at stomata
Leaf adaptations
Waxy
Waxy leaves Ilex aquifolia
Fatsia japonica- prevent water loss and protect against pests and excessive moisture
Leaf adaptations colour
Colour to absorb different colour lights- Heuchyra absorb red light at Forest floor
Silvery leaves reflect light in hot conditions
Bracts are sometimes the brightly coloured surfaces that attract pollinators Hydrangeas
Leaf adaptations
Change in shape/ reduced size
Leaves may curl or roll at edges to protect themselves from increased light intensity and heat and stop moisture loss- Citron family
Needle trees retain less water so as not to freeze in cold conditions and to allow heavy snow to slough off them
Where there is low humidity and high winds on exposed sites small leaves stop moisture loss through transpiration
Salvia rosemarinus
Gorses, bilberries have small leaves Vaccinium myrtillus
Leaf adaptations - variegation
Variegated leaves are selectively bred for aesthetics and are generally more slow growing due to having less chlorophyll
Hedera helix White Wonder
Leaf adaptations Succulent leaves
Thick leaves that are storing excess water in vacuoles- drought resistant, minimise water loss and retain water
Agave Americana
Leaf adaptations-aromatics
Leaves with oils in can be used to attract or deter insects
E.g Salvia, aliums
What are aeranchyma cells and where are they found?
They are spongy cell tissues that can be in leaf/ root or
Stem which create air spaces/ channels that allow a plant to float.
They are straw like in cross section and hold tissues in sulight
Water lilies Nymphaea
Fairy moss Azolla filiculoides
Leaf adaptations-
Bulbs
Leaves that have adapted to store food. An organ of perennation
Onion Hyacinth Daffodil Narcissus Bluebell
Leaf adaptations of Eucalyptus
Aromatic has oils that deter pests and are antibacterial
Shape changes -Juvenile leaves are round and the shape changes as it grows to create a larger photosynthesising surface
The glaucous blue colour and silver reflects heat, retaining moisture and transpiration
Leaf adaptations
Musa banana
Can withstand wind damage without affecting photosynthesising surface - rips along linear horizontal veins
Leaf adaptations Aspidistra
Parallel veins glossy leaves and waxy surface mean leaves direct rain water to the base of the plant
Leaf adaptations totipotency
Leaf lamina cuttings can be taken from some plants as all cells are able to generate stem tissues - root bud and leaf, so if we cut it and plant it the leaf tissue callouses and forms roots and identical genetic clones.
Zamioculcas zamiifolia
Leaf adaptations of Nicotiana sylvestris
Glutinous- stick leaves as a pest defense
Summary Leaf adaptations list of what they can do
Reduce transpiration
Increase humidity
Reflect or capture light
Cool leaf surface due to size or shape
Store water
Protection from herbivory
Create bouyancy
