From Muni university, Arua-Uganda. Good

1. BIO 2203
INTRODUCTORY PLANT AND
ANIMAL PHYSIOLOGY AND
HISTOLOGY
Dr. Omony John Bosco

2. Part A: What is a plant?
Definition - by most definitions, a plant:
 is multicellular;
 is non-motile
 has eukaryotic cells
 has cell walls comprised of cellulose
 is autotrophic; and
 exhibits alternation of generations - has a distinctive diploid (sporophyte) and haploid
(gametophyte) phase.
• Examples - the Plant Kingdom includes the angiosperms (flowering plants), gymnosperms
(cone-bearing plants), ferns, and bryophytes (mosses & liverworts).
• Recent classification systems suggest that these organisms, in addition to the red algae and
green algae, should be classified in the Plant Kingdom (Plantae).

3. PLANT PHYSIOLOGY
Plant physiology deals with various functions and processes occurring in plants. For
examples; metabolism, water relations, mineral nutrition, development, movement, irritability
study(response to the environment), growth, and transport processes.
Definitions (numerous) - plant physiology is the study of:
 The functions and processes occurring in plants
 The vital processes occurring in plants
How plants work
• In essence, plant physiology is a study of the plant way of life, which include various aspects
of the plant lifestyle and survival including: metabolism, water relations, mineral nutrition,
development, movement, irritability (response to the environment), organization, growth,
and transport processes.

4. Cont.……….
• These functions are performed by the protoplasm. Maintenance of life and activity of
protoplasm requires the following;
- Water for absorption of inorganic materials from the soil, provides medium for the
transportation of gases and soluble food in plants. Many chemical changes are also carried
out in solution in the plant body.
- Air, plants require oxygen for respiration and carbon dioxide for manufacturing food.
- Optimum heat of about 30oc maintains high activities of the protoplasm and all vital
processes carried out on it, since most physiological processes are controlled by enzymes.
- Light has a stimulating effect on growth, it’s responsible for green coloration of plants,
utilization of carbon dioxide of air and manufacturing of sugar and starch.
- Food for its nutrition.
Therefore, plant physiology is the study of life processes of plants.

5. Why study plant physiology?
• Food source: plants are the route by which solar energy enters ecosystems
• Economically important products: plants produce countless products such as fibres,
medicines and wood.
• Applications to other disciplines: applicable in agriculture, chemistry, forestry,
horticulture etc.
• Career purpose: industries, research institutes, jobs! Etc
• Theoretical importance in application of the theories and knowledge obtained to explain
other related fields –
Botany without borders is a good online film that highlights the importance of plants. It was
created by Dr. K Niklas (cornell).
How can you become a plant physiologists?
• Go through undergraduate training
• Join professional societies
• Read plant physiology and do related researches
• Perform tasks in several careers.

6. PLANT LIFE: UNIFYING PRINCIPLES of Plants
Plants are diverse in: size, form , shape or morphology
Plants range in size from less than 1 cm tall to greater than 100 m.
The tiny plant duckweed (Lemna) seems to have little in common with a giant saguaro
cactus (redwood).
all plants carry out fundamentally similar processes and are based on the same
architectural plan.
major design elements of plants :
As Earth’s primary producers, green plants are the e.

7. From smallest to largest plants
Duckweed (Lemna)
saguaro cactus (redwood)

8. Cont’
d…
Terrestrial plants:
• are structurally reinforced to support their mass as they grow toward sunlight against the pull
of gravity.
• lose water continuously by evaporation and have evolved mechanisms for
avoiding desiccation.
• have mechanisms for moving water and minerals from the soil to the sites of
photosynthesis and growth
Scope of plant physiology
The field of plant physiology includes the study of all the internal activities of plants - those
chemical and physical processes associated with life as they occur in plants.

9. Cont’d...
This includes study at many levels of scale of size and time.
Levels of organization
atoms > molecules > cells > tissues > organs > whole plant > pop.
 At the smallest scale are:
molecular interactions of photosynthesis
internal diffusion of water, minerals, and nutrients
At the largest scale are:
the processes of plant development,
seasonality, dormancy, and reproductive control.

10. Cont’d...
Major subdisciplines of plant physiology include:
 phytochemistry (the study of the biochemistry/ chemistry of plants)
 phytopathology (the study of disease in plants).
The scope of plant physiology as a discipline may be divided into several
major areas of research.

11. Cont’d…
First, the study of phytochemistry (plant chemistry) is included within the domain of
plant physiology. In order to function and survive, plants produce a wide array of
chemical compounds not found in other organisms.

12.  Photosynthesis requires a large array of pigments, enzymes, and other compounds to
function
 Plants must also defend themselves chemically from herbivores, pathogens
and competition from other plants.
Producing toxins and foul-tasting or smelling chemicals.
Other compounds defend plants against disease, permit survival during drought, and
prepare plants for dormancy.
While other compounds are used to attract pollinators or herbivores to spread ripe
seeds.
Cont’d…

13.  Secondly, it includes the study of biological and chemical processes of
individual plant cells.
Plant cells have a number of features that distinguish them from cells of animals.
plant cells have a cell wall which restricts the shape of plant cells and thereby limits the flexibility
and mobility of plants.
They also contain chlorophyll, a chemical compound that interacts with light in a way that
enables plants to manufacture their own nutrients rather than consuming other living things as
animals do.
Thirdly, plant physiology deals with interactions between cells, tissues, and organs within a
plant.
Cont’d…

14. Cont’d…
Different cells and tissues are physically and chemically specialized to perform
different functions.
Roots and rhizoids anchor the plant and acquire minerals in the soil.
Leaves function to catch light in order to manufacture nutrients.
For both of these organs to remain living, the minerals acquired by the roots must be
transported to the leaves and the nutrients manufactured in the leaves must be transported
to the roots.
Plants have developed a number of means by which this transport may occur, such as
vascular tissue.
The functioning of the various modes of transport is studied by plant physiologists.

15. Cont’d…
Fourthly, plant physiologists study the ways that plants control or regulate
internal functions.
plants produce chemicals called hormones which are produced in one part
of the plant to signal cells in another part of the plant to respond.
Many flowering plants bloom at the appropriate time because of light- sensitive
compounds that respond to:
The length of the night, a phenomenon known as photoperiodism.
Ripening of fruit and loss of leaves in the winter are controlled in part by the production
the gas ethylene by the plant.

16. Cont’d…
Finally, plant physiology includes the study of how plants respond to conditions and
in the environment, a field known as plant ecology or environmental physiology.
Stress from water loss
 changes in air chemistry or
crowding by other plants can lead to changes in the way a plant functions. These changes
may be affected by genetic, chemical, and physical factors.

17.  Physiological and biochemical functions of plants on structures, whether the process is:
• gas exchange in the leaf
•water conduction in the xylem,
• Photosynthesis in the chloroplast, or
• ion transport across the plasma membrane.
 Despite their apparent diversity, all seed plants have the same basic body plan. The
vegetative body is composed of three organs: leaf, stem, and root.
OVERVIEW OF PLANT STRUCTURE

18. • The primary function of a leaf is photosynthesis,
• The primary function of stem is support, and
• The root is anchorage and absorption of water and minerals.
Leaves are attached to the stem at nodes, and the region of the stem
between two nodes is termed the internode.
The stem together with its leaves is commonly referred to as the shoot.
There are two categories of seed plants: gymnosperms (from the Greek for “naked seed”)
and angiosperms (based on the Greek for “vessel seed,” or seeds contained in a vessel).
Cont’d…

19. Gymnosperms are the less advanced type; about 700 species are known. The largest group
of gymnosperms is the conifers (“cone- bearers”).They include such commercially important
forest trees as pine, fir, spruce, and redwood.
Angiosperms, the more advanced type of seed plant, first became
abundant about 100 million years ago.
They dominate the landscape, easily outcompeting the gymnosperms. About 250,000
are known, but many more remain to be characterized. The major innovation of the
is the flower; hence they are referred to as flowering plants.
Cont’d…

20. In animals, embryonic cells can migrate from one location to another, resulting in the
development of tissues and organs containing cells that originated in different parts of the
organism.
 In plants, such cell migrations are prevented because each walled cell
and its neighbor are cemented together by a middle lamella.
As a consequence, plant development, unlike animal development,
depends solely on patterns of cell division and cell enlargement.
Plant cells have two types of walls: primary and secondary
Primary cell walls are typically thin (less than 1μm) and are
characteristic of young, growing cells.
Plant Cells Are Surrounded by Rigid Cell Walls

21. Secondary cell walls are thicker and stronger than primary walls and are deposited when
most cell enlargement has ended.
Secondary cell walls owe their strength and toughness to lignin, a brittle,
glue like material.
The evolution of lignified secondary cell walls provided plants with the structural
necessary to grow vertically above the soil and to colonize the land. Bryophytes, which lack
lignified cell walls, are unable to
grow more than a few centimeters above the ground.
Cont’d…

22. Plants are multicellular organisms composed of millions of cells with specialized
functions.
At maturity, they may differ greatly from one another in their structures.
However, all plant cells have the same basic eukaryotic organization
Certain structures can be lost during cell maturation, but all plant cells begin
with a similar complement of organelles.
Biological Membranes are phospholipid bilayers that contain proteins.
increase the fluidity of their membranes.
According to the fluid-mosaic model, all biological membranes have the
same basic molecular organization.
THE PLANT CELL

23. They consist of a double layer (bilayer) of either phospholipids or, in the case of chloroplasts,
glycosylglycerides, in which proteins are embedded.
However, the composition of the lipid components and the properties of the
proteins vary from membrane to membrane, conferring on each membrane its
unique functional characteristics.
Plastid membranes are unique in that their lipid component consists almost entirely of
glycosylglycerides rather than phospholipids.
In glycosylglycerides, the polar head group consists of galactose,
digalactose, or sulfated galactose, without a phosphate group.
Cont’d…

24. The nucleus (plural nuclei) is the organelle that contains the genetic
information.
genes and their intervening sequences are referred to as the nuclear genome.
The size of the nuclear genome in plants ranging from about 1.2 × 108 base pairs for the
diminutive dicot Arabidopsis thaliana to 1 × 1011 base pairs for the lily Fritillaria assyriaca.
The remainder contained in the two semiautonomous organelles
 chloroplasts and mitochondria.
In plant cells, the Golgi body plays an important role in cell wall formation. Secretory :
Secretory vesicles carry the polysaccharides and glycoproteins to the plasma membrane.

25. New Cells Are Produced by Dividing Tissues Called Meristems
Plant growth is concentrated in localized regions of cell division called meristems. Nearly all
nuclear divisions (mitosis) and cell divisions (cytokinesis) occur in these meristematic regions.
In a young plant, the most active meristems are called apical meristems;
they are located at the tips of the stem and the root.
Question: Enumerate other plant cell organelles and state the physiologic functions?

26. PLASMODESMATA
Tubular extensions of the plasma membrane
Transverse the cell wall and connect the cytoplasms of adjacent cells
Plant cells are interconnected in this way, their cytoplasms form a continuum
referred to as the symplast.
Two types: primary and secondary
Primary plasmodesmata: newly deposited cell plate is penetrated by numerous
pores, not form uninterrupted sheet
Its development provides direct continuity and communication b/n cells that are
clonally related (derived from the same mother cells)

27. Secondary plasmodesmata form between cells after their cell walls
have been deposited.
 Increasing the communication between cells that are clonally related
Allow symplastic continuity between cells that are not clonally related.

28. Plant Cell Types
•Parenchyma – “normal plant cells”– has large vacuoles, no secondary cell
wall, usually not mitotic, but can be stimulated to divide in injury. Examples:
 Most of the cells that make up ground tissue
 Photosynthetic cells in leaf mesophyll
 Cells that store starch in stems and roots
 Fruit cells – store sugar
 Sieve tube cells that make up phloem

29. •Collenchyma – cells are elongated, thicker primary wall but no secondary cell wall,
provides for growth and support. Examples:
 Cells that support young stems and petioles
 Some ground tissue
•Sclerenchyma – are formed from a short thick walled plant cells called sclereids.
Have rigid secondary cells walls (can’t elongate),

30. •May be dead and used for plant support. Examples:
The shells of nuts and outer coat of seeds
Fiber cells – used to make plant fibers that are used to make rope
Tracheids and Vessel Elements (make up xylem) – dead water conducting
cells used for support

31. Plant body and tissue types
All plant organs (roots, stems, leaves) are composed of the
same tissue types.
• Roots
• Stems
• Leaves
Dermal : the outer most layer
Vascular : conducting tissue and transport
Ground : bulk of inner layer
Dermal
Vascular
Ground
Dermal
Vascular
Ground

33. Outsidelayer =
epidermis– dermal
tissuefor protection
Cortex = ground
tissue– storage of
food, uptake of
minerals
Steele= xylem and
phloem – vascular
tissue
Root Hairs – increase
surface area for
increasedwater
absorption

34. 1. Dermal tissue
• Epidermis is the outermost layer of cells
• Like the “skin” of animals
• In stems and leaves,
epidermis has cuticle,
a waxy layer that prevents water
loss.
• Some have trichomes, hairs.
• Root epidermis has root hairs, for water
and nutrient absorption

35. 2. Vascular tissue
• Transports water and organic materials (sugars) throughout
the plant
• Xylem – transports water and dissolved
ions from the root to the stem and
leaves.
•Phloem – carries dissolved sugars from leaves
to rest of the plant

36. Xylem
• Transports water and dissolved minerals
• Tracheids: long, thin tube like structures without perforations at the ends
• Vessel elements: short, wide tubes perforated at the ends (together form a pipe, called
vessel).
• Both cells have pits (thin sections) on the walls
Tracheids Vessel elements

37. Xylem cells
• Xylem cells are dead!
• They are hollow cells and
consist
only of cell wall

38. Phloem
• Cells that transport organic materials
(sugars)
(unlike xylem)
• Phloem cells are ALIVE!
• However, they lack
nucleus and
organelles

39. Phloem: transports sugars
Sieve tube member
• Phloem composed of cells called sieve tube
members (STM)
• Companion cells join sieve tube members, are related,
and help to load materials into STM
• End walls of STM have large pores called
sieve plates
Companion cells
Sieve plates

40. 3. Ground tissue
• Makes up the bulk of plant organs.
• Functions: Metabolism, storage and support.
Root Stem Leaf

41. Functions of plant organs:
• ROOTS: Anchorage, water/nutrient absorption from
soil, storage, water/nutrient transport
• STEMS: Support, water/nutrient transport
• LEAVES: Photosynthesis (food production)

42. ROOTS
• ROOTS “the hidden half”
• Functions of roots:
• Ancorage
• Absorption of water & dissolved minerals
• Storage (surplus sugars, starch)
• Conduction water/nutrients

43. Anatomy of a root
epidermis
cortex
vascular

44. Root Epidermis
• Outermost, single layer of cells
that:
– Protects (from diseases)
– Absorbs water and nutrients
• ROOT HAIRS: tubular
extensions of epidermal cells.
• Increase surface area of
root, for better
water/nutrient absorption

45. Root Cortex
• Stores starch, sugars and other substances

46. Root Ground tissue
• In roots, ground tissue (cortex) provides
support, and often stores sugars and starch
(for example: yams, sweet potato, etc.)
yam!
Sweet potato!
cortex

47. Root Cortex: Endodermis
• Endodermis: the innermost layer of the cortex

48. Root cortex: Casparian strip
• The Casparian strip is a water-impermeable
strip of waxy material found in the
endodermis (innermost layer of the cortex).
• The Casparian strip helps to control the
uptake of minerals into the xylem: they have
to go through the cytoplasm of the cell!

49. STEMS
• Above-ground organs (usually)
• Support leaves and fruits
• Conduct water and sugars
throughout plant (xylem and phloem)

50. Stem anatomy
• Dermal, ground and vascular tissues…
pith
cortex
epidermis
Vascular
bundles

51. Types of stems
• Herbaceous vs. Woody stems

52. Tissues of stems
• Epidermis (Dermal tissue type)
• Provides protection
• Has cuticle (wax) prevents water loss
• Trichomes (hairs) for protection, to release
scents, oils, etc.

53. Stem Vascular tissue
• Vascular bundles – composed of both
xylem and phloem
• Xylem
– Conducts water
– Support
• Phloem
– Conducts food
– Support
Vascular
cambium

54. Vascular cambium
• Occurs in woody stems
• Vascular cambium located in the middle of
the vascular bundle, between xylem and
phloem

55. Vascular tissue: Trees
• Vascular tissue is located on the outer
layers of the tree.
wood
xylem
bark
phloem
Vascular
cambium

56. Girdling: cutting around a tree
• Damages the phloem and xylem, eventually
killing the tree!

57. Vascular tissue forms rings in trees
• Annual rings: xylem formed by the vascular
cambium during one growing season
• One ring = one year

58. 1489: Tree is planted
by Native American
1492: Columbus lands in
the Americas
1620: Pilgrims land
in Plymouth, Mass.
1776: Declaration
of US independence
1861: Start of
Civil War
1969: Man
lands on Moon
1917 & 1945: Tree
Survives two World
Wars
1971: Birth Year
of the IDIOT
who cut down
this tree!!!
History of the tree: annual rings
Dendrochronology : tree time-keeping

59. Ground tissue: Cortex & pith
pith
• the central spongy tissue of the stem of a vascular plant is called
pith
• Stores food (e.g. potato)
• Site of Photosynthesis (when green)
• Support cells
cortex

60. LEAVES:
• ‘Photosynthetic factories’ of the plant…
• Function: Photosynthesis – food production for the whole plant
• Blade: Flat expanded area
• Petiole: stalk that connects leaf blade to stem, and
transports materials
BLADE

61. Leaf Anatomy
• Leaf anatomy is correlated to photosynthesis:
Carbon dioxide + Water sugars + oxygen
dermal
ground
vascular
dermal

62. Leaf epidermis
• Is transparent – so that sun light can go
through.
• Waxy cuticle protects against drying out
• Lower epidermis: stomata with guard cells – for gas
exchange (CO2, H2O in; O2 out)

63. Leaf epidermis
• Trichomes (give fuzzy texture)
(“Panda plant”)

64. Leaf vascular tissue
• VEINS  vascular tissue of leaves.
• Veins are composed of xylem (water transport)
phloem (food transport)
and bundle sheaths,
cells surrounding the
xylem/phloem for
strength & support

65. Leaf Mesophyll
• Middle of the leaf (meso-phyll)
• Composed of photosynthetic ground cells:
• Palisade parenchyma
(long columns below epidermis;
have lots chloroplasts for
photosynthesis)
Spongy parenchyma
(spherical cells)
with air spaces around,
(for gas exchange)

66. Plant Growth
New Cells Are Produced by Dividing Tissues Called Meristems.
In a young plant, the most active meristems are called apical meristems
At the nodes, axillary buds contain the apical meristems for branch shoots.
Lateral roots arise from the pericycle, an internal meristematic tissue.

67. Meristems embryonic tissue (stem cells – undifferentiated) – can divide and become any
kind of plant cell.
 Primary Meristems (apical) – make plant grow longer – in root
tips and at buds or new shoots.
 Secondary Meristems (lateral) – make plant grow wider – in stem
– adding more xylem which becomes wood.
The phase of plant development that gives rise to new organs and to the basic plant form is
called primary growth.
 Primary growth results from the activity of apical meristems

68. Secondary growth involves two lateral meristems: the vascular cambium and the
cork cambium.
The vascular cambium gives rise to secondary xylem (wood) and secondary phloem.
 The cork cambium produces the periderm, consisting mainly of
cork cells.
Xylem (wood) Over the years, vascular cambium makes many layers of
secondary xylem on the inside, this is wood

69. •Only the most exterior xylem works to carry water. Interior
xylem dies and hardens more.
Phloem (part of bark) Formed outside the vascular cambium
only newest xylem closest to interior is alive and transports food
– rest dies and sloughs off so doesn’t become thick like wood
part.
Cork cambium forms outside the phloem and makes cork cells
which fill with suberin
The epidermis cracks off and the outside becomes the cork cells
Bark = Phloem, Cork Cambium, Cork

70. Heartwood = dead,
older xylem
Sapwood = new
xylem still carrying
water
Phloem – carries
food - old phloem
sloughs