Biology - CARNES AP BIO · PDF file•Learning Objectives: ... Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level STIMULUS: rises to set point; Dropping blood

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

PowerPoint® Lecture Presentations for

Biology

Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

BIG IDEA II Biological systems utilize free energy and molecular building blocks

to grow, to reproduce and to maintain dynamic homeostasis.

Enduring Understanding 2.C

Organisms use feedback mechanisms to regulate growth and

reproduction, and to maintain dynamic homeostasis.

Essential Knowledge 2.C.1

Organisms use feedback mechanisms to maintain their internal

environments and respond to external environmental changes.


Essential Knowledge 2.C.1: Organisms use feedback mechanisms to

maintain their internal environments and respond to external environmental changes.

• Learning Objectives:

– (2.15) The student can justify a claim made about the effect(s) on a biological

system at the molecular, physiological or organismal level when a given scenario in

which one or more components within a negative regulatory system is altered.

– (2.16) The student is able to connect how organisms use negative feedback to

maintain their internal environments.

– (2.17) The student is able to evaluate data that show the effect(s) of changes in

concentrations of key molecules on negative feedback mechanisms.

– (2.18) The student can make predictions about how organisms use negative

feedback mechanisms to maintain their internal environments.

– (2.19) The student is able to make predictions about how positive feedback

mechanisms amplify activities and processes in organisms based on scientific

theories and models.

– (2.20) The student is able to justify that positive feedback mechanisms amplify

responses in organisms.


Negative feedback mechanisms maintain dynamic homeostasis for a particular variable by regulating physiological processes, returning the changing condition back to its target set point.

• Illustrative Examples Include:

– Temperature Regulation in Animals

– Plant Responses to Water Limitations


Temperature Regulation in Animals http://bcs.whfreeman.com/thelifewire/content/chp41/41020.html

http://bcs.whfreeman.com/thelifewire/content/chp41/41020.html


Plant Responses to Water Limitations http://www.phschool.com/science/biology_place/labbench/lab9/guard.html

http://www.phschool.com/science/biology_place/labbench/lab9/guard.html


Positive feedback mechanisms amplify responses and processes in biological organisms.

• The variable initiating the response is moved farther away from

the initial set-point.

• Amplification occurs when the stimulus is further activated

which, in turn, initiates an additional response that produces

system change.


Lactation in Mammals http://bcs.whfreeman.com/thelifewire/content/chp42/4202s.swf

http://bcs.whfreeman.com/thelifewire/content/chp42/4202s.swf


Onset of Labor in Childbirth http://www.johnwiley.net.au/highered/interactions/media/Foundations/content/Foundations/homeo4a/bot.htm

http://www.johnwiley.net.au/highered/interactions/media/Foundations/content/Foundations/homeo4a/bot.htm


Ripening of Fruit in Plants


Alteration in the mechanisms of feedback often results in deleterious consequences.

• Illustrative examples include:

– Diabetes mellitus in response to decreased

insulin.

– Grave’s disease (hyperthyroidism).


Maintenance of Glucose Homeostasis http://bcs.whfreeman.com/thelifewire/content/chp50/5002002.html

Beta cells of

pancreas are stimulated

to release insulin

into the blood.

Insulin

Liver takes

up glucose

and stores it

as glycogen.

Body cells

take up more

glucose.

Blood glucose level

declines to set point;

stimulus for insulin

release diminishes.

STIMULUS:

Rising blood glucose

level (for instance, after

eating a carbohydrate-

rich meal)

Homeostasis:

Blood glucose level

(about 90 mg/100 mL)

Blood glucose level

rises to set point;

stimulus for glucagon

release diminishes.

STIMULUS:

Dropping blood glucose

level (for instance, after

skipping a meal)

Alpha cells of pancreas

are stimulated to release

glucagon into the blood. Liver breaks

down glycogen

and releases

glucose into

blood. Glucagon

Figure 45.12

http://bcs.whfreeman.com/thelifewire/content/chp50/5002002.html


Diabetes Mellitus http://www.dnatube.com/video/2792/Animation-about-diabetes-and-the-body

http://www.dnatube.com/video/2792/Animation-about-diabetes-and-the-body












Thyroid Hormone: Control of Metabolism & Development http://www.biologyinmotion.com/thyroid/index.html

• The hypothalamus and anterior

pituitary control the secretion

of thyroid hormones through

two negative feedback loops:

– The hypothalamus secretes TSH-

releasing hormone (TRH), which

stimulates the anterior pituitary to

secrete thyroid-stimulating hormone

(TSH).

– TSH then stimulates the thyroid gland

to synthesize and release the thyroid

hormones T3 and T4.

– These hormones exert negative

feedback on the hypothalamus and

anterior pituitary by inhibiting the

release of TRH and TSH.

http://www.biologyinmotion.com/thyroid/index.html


Graves’ Disease


PowerPoint® Lecture Presentations for

Biology

Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

BIG IDEA II Biological systems utilize free energy and molecular building blocks

to grow, to reproduce and to maintain dynamic homeostasis.

Enduring Understanding 2.C Organisms use feedback mechanisms to regulate growth and

reproduction, and to maintain dynamic homeostasis.

Essential Knowledge 2.C.2 Organisms respond to changes in their external environments.


Essential Knowledge 2.C.2: Organisms respond to changes in their external environments.

• Learning Objectives:

– (2.21) The student is able to justify the selection of

the kind of data needed to answer scientific questions

about the relevant mechanisms that organisms use to

respond to changes in their external environments.


Organisms respond to changes in their environments through behavioral and physiological mechanisms.

• Illustrative examples include:

– Photoperiodism and phototropism in plants

(physiological response)

– Shivering and sweating in humans (physiological

response) – WATCH BOZEMAN VIDEO #19!

– Taxis and kinesis in animals (behavioral response)

– Chemotaxis in bacteria (behavioral response)

– Hibernation and migration in animals (behavioral

response) – WATCH BOZEMAN VIDEO #19!


Response & Natural Selection in Plants

• Response to information and communication

of information are vital to natural selection in

plants.

– In phototropism, changes in the light source

lead to differential growth, resulting in maximum

exposure of leaves to light for photosynthesis.

– In photoperiodism, changes in the length of

night regulate flowering and preparation for

winter.


Phototropism and Photoperiodism in Plants

• In plants, physiological events involve interactions

between environmental stimuli and internal

molecular signals (hormones).


Early Experiments on Phototropism

Figure 39.5

In 1880, Charles Darwin and his son Francis designed an experiment to determine

what part of the coleoptile senses light. In 1913, Peter Boysen-Jensen conducted an experiment to

determine how the signal for phototropism is transmitted.

EXPERIMENT

In the Darwins’ experiment, a phototropic response occurred only when light could

reach the tip of coleoptile. Therefore, they concluded that only the tip senses light. Boysen-Jensen

observed that a phototropic response occurred if the tip was separated by a permeable barrier (gelatin)

but not if separated by an impermeable solid barrier (a mineral called mica). These results suggested

that the signal is a light-activated mobile chemical.

CONCLUSION

RESULTS

Control Darwin and Darwin (1880) Boysen-Jensen (1913)

Light

Shaded

side of

coleoptile

Illuminated

side of

coleoptile

Light

Tip

removed

Tip covered

by opaque

cap

Tip

covered

by trans-

parent

cap

Base covered

by opaque

shield

Light

Tip separated

by gelatin

block

Tip separated

by mica


Fig. 39-8

Cross-linking polysaccharides

Cellulose microfibril

Cell wall becomes more acidic.

2

1 Auxin increases proton pump activity.

Cell wall–loosening enzymes

Expansin

Expansins separate microfibrils from cross- linking polysaccharides.

3

4

5

CELL WALL

Cleaving allows microfibrils to slide.

CYTOPLASM

Plasma membrane

H2O

Cell wall Plasma

membrane

Nucleus Cytoplasm

Vacuole

Cell can elongate.

Auxin


Photoperiodism and Responses to Seasons


Shivering & Sweating in Humans http://education-portal.com/academy/lesson/homeostasis-and-temperature-regulation-in-humans.html#lesson

http://education-portal.com/academy/lesson/homeostasis-and-temperature-regulation-in-humans.html#lesson














Taxis and Kinesis in Animals

• Environmental cues not only trigger some

simple behaviors in animals, but also

provide stimuli that animals use to change

or orient both simple and complex

movements in a particular direction.

– Kinesis: a change in activity or turning rate in

response to a stimulus.

– Taxis: an oriented movement toward (positive)

or away from (negative) some stimulus.


Kinesis

Dry open

area

Sow

bug

Moist site

under leaf


Taxis


Chemotaxis in Bacteria http://www.evolutionnews.org/2013/05/visualizing_che071811.html

http://www.evolutionnews.org/2013/05/visualizing_che071811.html


Oriented Movement: Migration


Nocturnal & Diurnal Activity

• Nocturnal activity is an animal behavior

characterized by activity during the night

and sleeping during the day.

• Diurnal animals, such as squirrels and

songbirds, are active during the daytime.

• Many times, these cycles are of adaptive

value to the organism.


Animal Dormancy

• Torpor: a DAILY FLUCTUATION in physiological state in which

activity is low and metabolism decreases; an adaptation that

enables animals to save energy while avoiding difficult and

dangerous conditions (these organisms are easily awakened)!

• Hibernation: (winter dormancy) - a long-term physiological

state in which metabolism decreases, the heart and

respiratory system slow down, and body temperature is

maintained at a lower level than normal during winter

months.

• Estivation: (summer dormancy) - a physiological state in

which metabolism decreases, the heart and respiratory

system slow down, and body temperature is maintained at a

lower level than normal during summer months.

Documents

Biology - CARNES AP BIO · PDF file•Learning Objectives: ... Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level STIMULUS: rises to set point; Dropping blood