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Diversity of Organisms

Structure and Function of Plants and Animals

Reproduction, growth, and development

Question #62: What patterns of reproduction and development are found in plants and animals and how

are they regulated?

Asexual Reproduction:

Budding -- part of individual undergoes repeated mitotic

divisions to produce a new individual that breaks off --

e.g. hydra, sea anemone.

Fragmentation part of parent falls off or is broken off

-- fragment undergoes repeated mitotic divisions to

produce an entire individual -- e.g. starfish, sponge.

Some species of animals have evolved from a

sexual mode of reproduction back to an asexual

mode:

Parthenogenesis -- development of new individuals from

ova that are not fertilized by male gametes

Sexual reproduction -- involves production of

haploid gametes and formation of zygotes

through fertilization

Fertilization may be external of internal to the

animal.

External fertilization-- usually seen in aquatic animals

such as fish -- -- probability of fertilization increased

by production of huge numbers of gametes.

Internal fertilization -- increases probability that egg

and sperm will meet and that fertilization will occur --

structural adaptations to facilitate passage of sperm

into female reproductive tract.

Development of a male

gametophyte

(in pollen grain)

(a)

Microsporangium

(pollen sac)

(b) Development of a female

gametophyte (embryo sac)

Microsporocyte

Microspores (4)

Each of 4

microspores

Generative cell

(will form 2

sperm)

(LM)

75 m 20 m

100

m

MEIOSIS

MITOSIS

Male

gametophyte

(in pollen grain)

Nucleus of tube cell

Ragweed

pollen

grain

(colorized

SEM)

Key to labels

Haploid (

n

)

Diploid (2

n

)

(LM)

Embryo sac

Ovule

Megasporangium

Megasporocyte

Integuments

Micropyle

Surviving

megaspore

Antipodal cells (3)

Polar nuclei (2)

Egg (1)

Synergids (2)

Ovule

Integuments

F

em

al

e

g

am

et

o

p

h

y

te

(em

b

ry

o

sa

c)

Figure 38.3

Double Fertilization

Stigma

Pollen

tube

2

3

1

2 sperm

Style

Ovary

Ovule

Micropyle

Pollen

grain

Polar

nuclei

Egg

Ovule

Polar

nuclei

Egg

Synergid

2 sperm

Endosperm

nucleus (3n)

(2 polar nuclei

plus sperm)

Zygote

(2n)

21.1: Embryonic development involves cell division,

cell differentiation, and morphogenesis,

Embryonic development of multi-cellular organisms

A single-celled zygote

cells

tissues

organs

organ systems

organisms

Figure 21.3a, b

(a) Fertilized eggs

of a frog

(2)

The three processes of development overlap in time

Figure 21.4a, b

Animal development. Most

animals go through some variation of the blastula and gastrula stages. The blastula is a sphere of cells surrounding a fluid-filled cavity. The gastrula forms when a region of the blastula folds inward, creating a tube—a rudimentary gut. Once the animal is mature, differentiation occurs in only a limited way—for the replacement of damaged or lost cells.

Plant development. In plants with seeds, a complete embryo develops within the seed. Morphogenesis, which involves cell division and cell wall expansion rather than cell or tissue movement, occurs throughout the plant’s lifetime. Apical meristems (purple) continuously arise and develop into the various plant organs as the plant grows to an indeterminate size.

Zygote (fertilized egg)

Eight cells Blastula (cross section)

Gastrula (cross section)

Adult animal (sea star) Cell

movement Gut

Cell division

Morphogenesis

Observable cell differentiation

Seed leaves

Shoot apical meristem

Root apical meristem

Plant Embryo inside seed Two cells

Zygote (fertilized egg) (a)

(b)

A summary of gene activity during

Drosophila

development

Hierarchy of Gene Activity in Early Drosophila Development

Maternal effect genes (egg-polarity genes)

Gap genes

Pair-rule genes

Segment polarity genes

Homeotic genes of the embryo

Other genes of the embryo

Segmentation genes

of the embryo

Widespread Conservation of

Developmental Genes Among Animals

Homeotic Genes are also called

Hox genes in animals

All homeotic genes contain a 180

NT homeobox region, coding for

a 60 AA homeodomain protein

Protein that acts as a selective transcription

factor

Figure 21.23

Adult fruit fly

Fruit fly embryo (10 hours)

Fly chromosome

Mouse chromosomes

Mouse embryo (12 days)

Adult mouse

Mechanisms of Plant Development

Cell lineage is much less important for pattern formation in

plants than in animals because most cells are totipotent

(reduced role of cytoplasmic determinants)

Development regulated by cell signaling and transcriptional

regulation

Signals can come from environment (sunlight, temp., gravity, etc.) and from cell

position

The embryonic development of most plants occurs inside

the seed making it harder to study

Morphogenesis and Differentiation can be studied at the

apical meristems

ALTERNATION OF GENERATION

GAMETOPHYTE GENERATION

All cells haploid (1N)

Grow from haploid spores

SPOROPHYTE GENERATION

Most cell diploid (2N)

Grow from diploid zygote

Produce haploid spores

Facilitates dispersal (happens

twice, with spores and gametes)

Question #63: What is the adaptive significance of alternation of generations in the

major groups of plants?

BRYOPHYTES: Nonvascular Plants

(not monophyletic)

Dominant Gametophyte

Mature sporophytes

Young sporophyte

Male gametophyte

Raindrop Sperm

Key

Haploid (n) Diploid (2n) Antheridia

Female gametophyte

Egg Archegonia

FERTILIZATION

(within archegonium) Zygote

Archegonium Embryo

Female gametophytes

Gametophore

Foot Capsule (sporangium) Seta Peristome

Spores Protonemata

“Bud”

“Bud”

MEIOSIS

Sporangium

Calyptra

Capsule with peristome (LM)

Rhizoid

Mature sporophytes Spores develop into threadlike protonemata.

1

The haploid protonemata produce “buds” that grow into gametophytes.

2

Most mosses have separate male and female gametophytes, with antheridia and archegonia, respectively.

3

A sperm swims through a film of moisture to an archegonium and fertilizes the egg.

4

Meiosis occurs and haploid spores develop in the sporangium of the sporophyte. When the sporangium lid pops off, the peristome “teeth” regulate gradual release of the spores.

8

The sporophyte grows a long stalk, or seta, that emerges from the archegonium.

6

The diploid zygote develops into a sporophyte embryo within the archegonium.

5

Attached by its foot, the sporophyte remains nutritionally dependent on the gametophyte.

(3)

SEEDLESS VASCULAR PLANTS

SPORE

bisexual gametophyte

Flagellated sperm generated by Antheridium swim

Evolution of Seed Plants

Reduced Gametophyte stage:

protected and nourished inside

sporophyte tissue

Heterosporous: separate male and

female gametophytes

Seed replaces spore for mechanism of

disperal

Megaspore develops within ovule

Microspore develop into pollen grain,

replacing flagellated sperm

Sporophyte dependent on gametophyte (mosses and other bryophytes).

(a) Large sporophyte and small, independent gametophyte (ferns and other seedless vascular plants).

(b)

Microscopic female gametophytes (n) in ovulate cones (dependent)

Sporophyte (2n), the flowering plant (independent) Microscopic male gametophytes (n) inside these parts of flowers (dependent)

Microscopic male gametophytes (n) in pollen cones

(dependent) Sporophyte (2n) (independent)

Microscopic female gametophytes (n) inside these parts of flowers (dependent)

Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms). (c)

Gametophyte (n)

Gametophyte (n) Sporophyte (2n) Sporophyte

(2n)

Gymnosperm Life Cycle

Demonstrates key adaptations: dominance of sporophyte generation;

the advent of the resistant, dispersible seed; evolution of pollen that

brings gametes together.

Angiosperm Life Cycle

Structural, physiological, and behavioral adaptations

Question #64:

How does the organization of cells, tissues, and

organs determine structure and function in plant and animal

systems?

Contact with the environment

Diffusion

(a) Single cell

Mouth

Gastrovascular

cavity

Diffusion

Diffusion

(b) Two cell layers

•Cells require contact with aqueous medium

•Surface to Volume Ratio important, especially for simple

organisms lacking circulatory systems

•In Complex Organisms: common theme is extensive folding and

branched internal surfaces

Length = 5 Surface Area = 150 Volume = 125 Surface/Volume Ratio = 1.2

(4)

Internal exchange surfaces of complex animals

External environment

Food CO2 O2

Mouth

Animal body

Respiratory system

Circulatory system

Nutrients

Excretory system Digestive

system

Heart

Cells

Interstitial fluid

Anus Unabsorbed matter (feces)

Metabolic waste products (urine) The lining of the small intestine, a diges-

tive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM).

A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).

Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). 0.5 cm

10 µm

5

0

µ

m

Cells

organized into Tissues

organized into Organs

organized into Organ Systems

Structure and Function in Animal Tissues

EPITHELIAL TISSUE

Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function.

A stratified columnar epithelium

A simple columnar

epithelium A pseudostratified ciliated columnar epithelium

Stratified squamous epithelia Simple squamous epithelia

Cuboidal epithelia

Basement membrane

40 µm

Epithelial tissue covers the

outside of the body and

lines organs and cavities

within the body with tightly

packed cells

Glandular Epithelial:

absorb or secrete

Organized by shape and

Pattern:

Simple: one layer

Stratified: multiple layers

Cuboidal: cube-shaped

(secretion)

Columnar: column

(secretion/absorption)

Squamous: floor tiles

(diffusion, or protection)

Connective tissue functions mainly to bind and support other tissues

Collagenous fiber Elastic fiber

Chondrocytes Chondroitin sulfate

Loose connective tissue

Fibrous connective tissue

100

µm

100 µm

Nuclei

30 µm

Bone Blood

Central canal

Osteon

700 µm 55 µm

Red blood cells White blood cell Plasma

Cartilage

Adipose tissue

Fat droplets

1

5

0

µ

m

CONNECTIVE TISSUE

The major types of

connective tissues in

vertebrates:

Loose connective tissue:

packing material

Adipose tissue: cushioning,

energy storage

Fibrous connective tissue:

Tendons (join muscles to

bones) and Ligaments (hold

bones together)

Cartilage: flexible support

Bone: mineralized, hard

support

Blood: transport and defense

Each has a structure

correlated with its specialized

function

Organs and Organ Systems:

Many organs have multiple tissue layers, held in place my mesenteries

inside body cavities

Organs are organized into Organ Systems

Morphology of a Flowering Plant

Flower:

Reproductive Adaptation of Angiosperms

Sepals: leaves enclose flower

Petals: attract pollinators

Stamens: male reproductive structure

consisting of - anther and filament

Carpels: female reproductive structure

consisting of - stigma, style, and ovary

Incomplete flowers- (grasses) lack at

least one of 4 major parts

Unisexual flower- have only male or

female parts

(5)

Examples of Differentiated Plant Cells

PARENCHYMA CELLS

COLLENCHYMA CELLS

SCLERENCHYMA CELLS

SUGAR-CONDUCTING CELLS OF THE PHLOEM WATER-CONDUCTING CELLS OF THE XYLEM

Parenchyma cells 60 m 80 m

5 m

25 m

Cell wall

Sclereid cells in pear

Fiber cells

Cortical parenchyma cells

Collenchyma cells

Vessel Tracheids 100 m

Tracheids and vessels

Vessel element

Vessel elements with partially perforated end walls

Pits

Sieve-tube members: longitudinal view

Companion cell

Sieve-tube member Sieve plate Nucleus

Cytoplasm Companion cell

30 m 15 m

Tracheids

Photosynthesis

Flexible support

Rigid support

Tissue Organization of Leaves

Flexible support

Photosynthesis

Protective layer

Protective layer

Question #65: How are structure and function related in the various organ systems

and how do the organ systems of animals interact?

41.4: Each organ of the mammalian digestive

system has specialized food-processing functions

IIeum of small

intestine Duodenum of small intestine

Appendix Cecum Ascending portion of large intestine

Anus Small intestine Large intestine Rectum Liver

Gall- bladder Tongue

Oral cavity Pharynx

Esophagus

Stomach Pyloric sphincter

Cardiac orifice

Mouth Esophagus

Salivary glands

Stomach

Liver Pancreas Gall- bladder

Large intestines Small intestines

Rectum Anus Parotid gland

Sublingual gland Submandibular gland Salivary glands

A schematic diagram of the human digestive system

Pancreas

Absorption of Nutrients

The small intestine has a huge surface area due to

the presence of villi and microvilli that are exposed

to the intestinal lumen absorption.

Epithelial cells

Key

Nutrient absorption

Vein carrying blood to hepatic portal vessel

Villi

Large circular folds

Intestinal wall Villi

Epithelial cells

Lymph vessel Blood

capillaries

Lacteal Microvilli (brush border)

Muscle layers

FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS

Systemic capillaries

Systemic capillaries

Systemic capillaries

Systemic capillaries

Lung capillaries

Lung capillaries

Lung and skin capillaries

Gill capillaries

Right Left Right Left Right Left

Systemic circuit Systemic

circuit Pulmocutaneous

circuit

Pulmonary

circuit Pulmonary circuit

Systemic circulation

Vein Atrium (A) Heart: ventricle (V) Artery Gill circulation

A

V V

V V V

A A A Left Systemic A A

aorta Right

systemic aorta

Figure 42.4

(6)

The effectiveness of gas exchange in some gills

Countercurrent exchange

Figure 42.21

Gill arch

Water flow Operculum

Gill arch

Blood vessel

Gill filaments

Oxygen-poor blood Oxygen-rich blood

Water flow over lamellae showing % O2

Blood flow through capillaries in lamellae showing % O2

Lamella

O2

Lungs

Branch from the pulmonary vein (oxygen-rich blood) Terminal bronchiole

Branch from the pulmonary artery (oxygen-poor blood)

Alveoli

Colorized SEM SEM

5

0

µ

m

5

0

µ

m

Heart Left lung Nasal cavity Pharynx

Larynx

Diaphragm Bronchiole Bronchus Right lung Trachea Esophagus

How a Bird Breathes

INHALATION Air sacs fill

EXHALATION Air sacs empty; lungs fill Anterior

air sacs

Trachea

Lungs Lungs

Posterior air sacs

Air Air

1 mm Air tubes

(parabronchi) in lung

Figure 42.25

Figure 44.13c, d

Juxta- medullary nephron

Cortical nephron

Collecting duct

To renal pelvis

Renal cortex

Renal medulla

20 µm Afferent arteriole from renal artery Glomerulus

Bowman’s capsule Proximal tubule

Peritubular capillaries

SEM Efferent arteriole from glomerulus

Branch of renal vein Descending limb Ascending limb Loop

of Henle

Distal tubule

Collecting duct

(c) Nephron

Vasa recta

(d) Filtrate and blood flow

Concept 48.5: The vertebrate nervous system is regionally

specialized

In bilateral organisms, particularly vertebrates, the nervous

system shows a high degree of cephalization and distinct CNS

and PNS components

CNS: Brain and Spinal cord

PNS: Nerves and Ganglia

Figure 48.19

Central nervous

system (CNS) Peripheral nervous system (PNS)

Brain Spinal cord

Cranial nerves

Ganglia outside CNS Spinal nerves

The Peripheral Nervous System

The PNS transmits information to and from the CNS

Crucial in regulating a vertebrate’s movement and internal

environment

The PNS has two functional components

The somatic nervous system and the autonomic nervous system

Peripheral nervous system

Somatic nervous system

Autonomic nervous system

Sympathetic division

Parasympathetic division

Enteric division

(7)

Parasympathetic division Sympathetic division Action on target organs: Action on target organs: Location of

preganglionic neurons:

brainstem and sacral segments of spinal cord

Neurotransmitter released by preganglionic neurons:

acetylcholine

Location of postganglionic neurons:

in ganglia close to or within target organs

Neurotransmitter released by postganglionic neurons:

acetylcholine

Constricts pupil of eye

Stimulates salivary gland secretion

Constricts bronchi in lungs

Slows heart

Stimulates activity of stomach and

intestines

Stimulates activity of pancreas

Stimulates gallbladder

Promotes emptying of bladder

Promotes erection of genitalia

Cervical

Thoracic

Lumbar

Synapse Sympathetic ganglia

Dilates pupil of eye

Inhibits salivary gland secretion

Relaxes bronchi in lungs

Accelerates heart

Inhibits activity of stomach and intestines

Inhibits activity of pancreas

Stimulates glucose release from liver; inhibits gallbladder

Stimulates adrenal medulla

Inhibits emptying of bladder

Promotes ejaculation and vaginal contractions Sacral

Location of preganglionic neurons:

thoracic and lumbar segments of spinal cord

Neurotransmitter released by preganglionic neurons:

acetylcholine

Location of postganglionic neurons:

some in ganglia close to target organs; others in a chain of ganglia near spinal cord

Neurotransmitter released by postganglionic neurons:

norepinephrine

Figure 48.22

Rest and Digestion

Fight or Flight

Segregation of Resources

Problem: In aquatic plants, minerals and water are in

same location. In land plants, the minerals and water

are in the ground while sunlight and most CO

2

are

above ground.

Solutions: Specialization of Tissues

Roots- lack waxy cuticle, lack chloroplasts, have very large

surface area that is increased with help from mycorrhiza.

Stems- connect the root tissue to leaf tissue. Vascular

tissue

Leaves- contain chloroplasts for photosynthesis, leaves

tend to be broad and flat and contain pores for gas

exchange.

Question #66: What adaptive features have contributed to the success of various plants and

animals on land?

Tall Plants

Problem: As plants get taller to compete for sunlight, the specialized tissues

(leaves, roots) get farther away from each other.

Solutions:

Root Pressure: using active transport of nutrients, water enters the roots

through osmosis pushing itself up the plant a small way.

Capillary Action: due to the adhesion of water to the walls of thin xylem

cells and the cohesion of water molecules to each other, water creeps up

the thin xylem tubes

Transpiration Pull: as water evaporates from leaves, more water moves up

the plant due to osmosis and cohesion of water molecules to each other.

Xylem moves water up and Phloem moves sugars and other nutrients up or

down to where it is needed.

Capillary

Action

Drying Out

Problem: How to avoid drying out above ground while at the

same time meet the need to exchange gases (take in CO2 and

release excess O2).

Solutions

Waxy cuticle on surface of leaf is waterproof and prevents

water loss from evaporation. Does not allow gas exchange

Drying Out

Solutions

Stomata- small openings in underside of leaves allow gas

exchange.

Guard Cells- regulate opening and closing of stomata

When guard cells are hydrated, they are swollen and stomata is

open

When guard cells are dehydrated, they are shriveled and

stomata is closed.

Gravity

Problem: Plants floating in water are supported by the water. Plants

on land have to overcome gravity to grow vertically.

Solutions:

Cell walls are rigid to support the cell

Roots, anchor plant and help hold it up

Turgor Pressure: the large vacuole inside cell pushes out on cell

when full

(8)

The evolution of amniotes from an amphibian

ancestor involved many adaptations for

terrestrial living including

the amniotic egg

waterproof skin

increasing use of the rib cage to ventilate the lungs.

Internal lungs vs. gills

Question #67: What are the responses of plants and animals to environmental cues,

and how do hormones mediate them?

Plant Hormones

Auxins: Stem elongation; root growth, differentiation, and branching;

development of fruit; apical dominance; phototropism and

gravitropism

Cytokinins: root growth and differentiation; stimulate cell division

and growth; stimulate germination; delay senescence.

Gibberelins: Promote seed and bud germination, stem elongation,

and leaf growth; stimulate flowering and development of fruit; affect

root growth and differentiation.

Abscisic Acid: Inhibits growth; closes stomata during water stress;

promotes seed dormancy.

Ethylene: Promotes fruit ripening; opposes some auxin effects;

promotes or inhibits growth and development of roots, leaves and

flowers, depending on species.

Control Systems

Phytochromes: Light sensitive pigments.

Detect duration and intensity of light.

Plants also show responses to

Environmental Stress: water deficit, oxygen

deprivation, salt stress, heat stress, cold

stress, herbivores.

Major human endocrine glands and some of their

References

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