2.3 Structure and function of plant parts Flashcards
The external structure of a typical angiosperm has two major systems:
Shoot and root system
_ is the plant part usually found above the ground and includes the organs such as stem, branches, leaves, buds, flowers and fruits.
The shoot system
T/F
Leaves and branches may be missing from an angiosperm depending on the reproductive stage of the plant.
False, it’s flowers and fruits
_ is the part of the plant that usually grows downward into the ground.
The root system
_ includes the primary or tap root, lateral or branch roots, root hairs and root cap.
The root system
_ are distinguished from
an underground stem in that, it does not bear either leaves or buds.
Roots
The external structure of a typical leaf consists of the _, _, _, _, _, _ and _.
petiole (leaf stalk), lamina (blade – broadest part), veins, midrib, margin, base and tips (apex)
The _ is the broadest part, which is flat, wide and commonly thin.
lamina
_ provides large surface area, which enables leaf to collect light.
Lamina
The _ thinness creates short distance for gas exchange through the _.
lamina, stomata
The _ is harder than the lamina and contains the vein (transporting vessels) of the leaf as well as supportive tissues with hard cell wall.
midrib
With regard to root, there are basically two types of roots, namely _ and _.
tap-roots and fibrous roots
A _ consists of one large, primary vertical root.
tap-root
_ has very few lateral roots that develop and grow from this main root.
tap-root
By penetrating deep into the soil, _ provide stability (anchorage) and absorb water located deep in the ground.
tap roots
Tap root system is a feature of _ plants.
dicot
A _ is usually formed by thin, moderately branching roots growing from stems.
fibrous root
T/F
The lateral roots in fibrous roots are different in length.
False, they are more or less similar size and length.
In grasses, _ develop as consists of fine hair – like root that spread out from the base of the stem.
fibrous roots
_ is very efficient for absorbing water and minerals close to soil surface.
Fibrous root
_ creates a thick network of roots that are good at holding soil together and protect soil from erosion.
Fibrous root
Fibrous roots are features of _ plants .
monocot
There are two internal layers of a leaf, namely; _ and _.
Outer layer and middle (inner) layer
Outer layer is also known as the _, a single layer of tightly packed cells that covers the upper and lower surface of the leaf
epidermis
The _ epidermis is usually covered by a waxy cuticle, which transmits sunlight for photosynthesis but restricts water loss by evaporation from the leaf tissue.
upper
The _ epidermis usually contains bean-shaped guard cells that leave open spaces known as stomata (singular
stoma).
lower
_ are “little mouths” or “ little noses”, which regulate O2 release, CO2 intake and water loss.
Stomata
In most leaves, stomata are
more abundant in the _ epidermis, reducing water loss due to direct sunlight.
lower
Middle layer is known as the _ (“middle leaf”) layer
mesophyll
_ lies between the upper and lower epidermis.
Mesophyll layer
_ includes tissues that are directly or indirectly involved in photosynthesis.
Mesophyll layer
There are two regions in the mesophyll layer:
The palisade and spongy layer
The _ layer is composed of regularly arranged and closely packed columnar (vertically elongated) cells.
palisade
The cells in the _ contain the largest number of chloroplasts per cell.
palisade layer
As the _ is immediately beneath the upper epidermis, it is in the best position to capture most of the sunlight and this enables it to carry out most of the photosynthesis.
palisade layer
The slight but precise separation of the columnar cells in the _ maximizes the diffusion of CO2 and capillary movement of H20.
palisade layer
_ lies below the palisade cells.
The spongy layer
_ are irregularly shaped with fewer chloroplasts.
Spongy cells
_ are very loosely arranged with numerous airspaces.
Spongy cells
The air spaces in the _, which are very close to the stomata allow the diffusion of O2, water vapor and CO2.
spongy layer
The _ is the outermost layer of the stem.
epidermis
The _ walls are greatly thickened with cuticles, which minimizes the rate of transpiration.
outer
In the _, the cells are compactly arranged, which in turn protect the underlying tissues from mechanical injury and prevent the entry of harmful organisms.
epidermis
_ lies below the epidermis.
Hypodermis
_ is mainly composed of
collenchyma cells that are specially thickened at the corners due to the deposition of thick cellulose.
Hypodermis
_ gives mechanical strength to the stem.
Hypodermis
_ consists of few layers of thin-walled, large, round, or oval cells, having intercellular space and serving for storage of food.
Cortex
_ is the innermost layer of the cortex that separates the cortex from the vascular bundles.
Endodermis
T/F
In endodermis, the cells are widely arranged and usually contain starch grains.
False, they are compactly arranged
_ serves as a food reserve and may be termed as a starch sheath.
Endodermis
_ are longitudinal strands of conducting tissues or transporting vessels, consisting essentially of xylem and phloem arranged in a ring around the central pith.
Vascular bundles
Each vascular bundle has a
patch of xylem towards the _ and a patch of phloem towards the _ and a strip of actively dividing young cells (cambium) in between them.
pith, endodermis
_ transports water and dissolved minerals to the photosynthetic tissues, mainly to the leaf while _ transports synthesized food to different tissues, either for utilization or storage.
Xylem, phloem
_ occupies the central portion of the stem, composed of thin-walled cells, which are rounded or polygonal, with or without intercellular space.
Pith
_ stores food and helps in the internal translocation of water
Pith
_ is the outermost layer made up of single-layer cells.
Peliferous layer
In piliferous layer, the _ is absent.
cuticle
_ consists the single-celled root hairs.
Piliferous layer
_ is a multi-layered large zone made of thin-walled oval or rounded loosely arranged cells with intercellular spaces.
Cortex
_ stores food and water.
Cortex
_ is the innermost layer of the cortex, made of barrel-shaped closely packed cells.
Endodermis
_ helps the movement of water
and dissolved nutrients from the cortex into the xylem
Endodermis
_ is a single layer inner to endodermis.
Pericycle
_ is the site of origin of lateral roots.
Pericycle
_ consist of xylem and phloem with meristematic (cambium) or actively dividing cells between them
Vascular bundles
_ is present in young roots while absent in old roots.
Pith
Pith is present in _ roots while absent in _ roots.
young, old
