1. 4/3 ATB
What is hibernation?
Today:
Go over test
Describe photoperiod

2. 4/10 ATB What is photoperiod? Today:
Begin quick chapter on photoperiod and hibernation.

3. Photoperiod & Hibernation

4. Photoperiod Photoperiod (or photoperiodism) – Examples:
What makes light so important?
Energy source for photosynthesis
But also plays an important influencing plant / animal behavior
Photoperiod (or photoperiodism) –
Duration of an organism's daily exposure to light and…
…the effects of the exposure on the organism
Examples:
Growth
Development

5. 4/11 ATB
Name at least three examples of how photoperiod can affect organism behavior.
Today:
Continue discussing lights affects on organisms
Turn in article questions
Test – next Tuesday?
PSSA’s
Pd 1 – E218 (Mr. Freeman)
Pd 3 – A202

6. Photoperiod – Affect on Plants
What main purpose of light in plants?
Photosynthesis
What is the graph below stating?
As light (irradiance) increases, the rate of photosynthesis increases until saturation point is met
Why doesn’t the rate of photosynthesis continue to increase?
Because the cellular machinery is saturated or at “full capacity”

7. Light Tolerances Remember: Shade tolerant vs. shade intolerant
Different plants have different tolerances for the length of the photoperiod
Look at the graph:
Which is the “shade” leaf? How do you know?
B. Faster growth with lower light. Saturation point reached sooner

9. Light – Other influences on Plants
Acts as a Timing mechanism
Keeps plants in tune with daily and seasonal changes
Triggers plant activities
Leaves unfolding or falling off
Production of flowers and seeds
Some bloom in lengthening days of spring to make the most out of the available sunlight
Some flower only during days of shortening daylight

10. Critical daylength - Example:
The duration of light (or dark) that it inhibits or promotes a response from the organism
Usually falls between hours
Example:
Only in 10 hours of daylight will a plant bloom

11. Short-day vs. Long-day Plants
Short-day Plants –
Only bloom when amount of light is LESS than their critical period
EX: Only flower when there is LESS than 10 hrs of light
Long-day organisms -
Only bloom when amount of light is MORE than their critical period
EX: Only flower
when there is MORE
than 10 hrs. of light

12. Short-day vs. Long-day Plants

13. It actually may be the length of the DARK period rather than the light that controls the organisms response.
The terms long day/short day plants are actually misnomers. Research has proved that when the long night period was interrupted by a brief exposure to light, the plants failed to flower. So the scientists concluded that what is essential for flowering is long and uninterrupted dark period rather than a short day length. A brief interruption of the dark period with light nullified the effect of long night. So short day plants were called long night plants and long day plants were called short night plants.

14. 4/12 ATB
What is a critical day length?
Today:
Circadian rhythms

15. Day-Neutral Day-neutral organisms –
not affected by daylength
Examples: Tomatoes, cucumbers, sunflower, dandelions and cotton
What could be some signaling factors for these organisms?
Rain, temperature or others

16. How do horticulturists (people who cultivate plants) exploit short-day and long-day responses?
Forcing plants to bloom throughout the year using artificial light
How you get flowers in middle of winter

17. Circadian rhythm Circadian rhythm - Biological clock
Rhythm of activity and inactivity covering 24 hours characteristic of living things
Biological clock
Timekeeper of physical / physiological activity in livings things
Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including human beings.
Circa = around
diem or dies = "day”

18. Examples: Growth of antlers in male deer (hormonal changes)
Reproductive cycle of deer / sheep – shortening days of fall
Birds -- breeding season during the longest days

19. Rhythms of Waking and Sleep
What is jet lag?
disruption of the circadian rhythms due to crossing time zones.
mismatch of the internal circadian clock and external time.
Characterized by sleepiness during the day, sleeplessness at night, and impaired concentration.
Traveling west “phase-delays” our circadian rhythms.
Traveling east “phase-advances” our circadian rhythms.

20. Figure 9.6: Jet lag.
Eastern time is later than western time. People who travel six time zones east fall asleep on the plane and then must awaken when it is morning at their destination but still night back home.

21. 4/13 ATB What is jet lag? Today
Finish chapter – hibernation and feeding habits
Finish article

22. Light also affects when species become active in search of food

23. Nocturnal Nocturnal - Organisms that are adapted to night activity
Usually have highly developed sense of smell and/or hearing and/or eyesight
Some organisms can function during the day or night (cats)
Others are strictly nocturnal (bats, bushbabies)
Many have large eyes in order to see in low light conditions

24. Diurnal Diurnal - Examples:
Organisms that are active during the day (sleep at night)
Examples:
Squirrels, many birds

25. Crepuscular Crepuscular -
Organisms that are active during twilight periods (during dawn and dusk)
Crepusculum - meaning "twilight”
Evolved as a possible way to avoid predators who may be active during the middle of the day or during the night
Examples:
Cats, dogs, rabbits, skunks, deer

26. Torpor Torpor (“temporary hibernation”) –
State in animals where body temp. falls, metabolism decrease and O2 intake falls
Usually to save energy during cold temps
Can be short term or long term
Body restores to normal when the animal becomes active
Seen as a way to save energy when the animal is not active
Will awaken to stimuli
Young bats w/o enough stored energy may die

27. Examples: Lungfish Hummingbirds, mice, bats
may use this when their pool dries up
Have lungs – can breath air
Hummingbirds, mice, bats

28. Hibernation Hibernation –
Body temps drops to (almost) environmental temp (almost freezing)
Substantial drop in metabolic rate
Lower oxygen intake
Animals may wake, but not from stimuli (like predators, making them easy prey if found)
What is the goal?
survive during periods of cold weather with little food
Organisms must eat large amounts of food prior to hibernation
Examples: Woodchuck, ground squirrels some rodents

29. Winter hibernation - Winter's Tale - BBC
Black bear and cubs in hibernation - BBC wildlife
‪Waking up from Hibernation - Animals: The Inside Story – BBC‬

30. Do bears hibernate? Most do not consider it a “true” hibernator
Body temp. does drop, but not as much as a “true hibernator”
Metabolism does decrease
Heart rate does decrease
Totally rely on large amounts of stored energy in their fat
Do not eat, drink, defecate or urinate

31. The End

32. 4/16 ATB What happens to an organisms body as they enter hibernation?
Today:
Review for the test
Test / Study Guide – Tomorrow
Don’t forget PSSA’s
Pd. 1 – E218 (Mr. Freeman)
Pd. 3 – A202

33. IV. Abiotic Factors: Light
Major concepts in this unit:
a. how light is measured
b. plant adaptations to light
c. circadian rhythms and animals
d. biological clocks
e. photoperiodism/phenology
f. Subunit: Raptors (highlight diurnal/nocturnal adaptations)
g. Subunit: Whitetail deer (highlight periodicity in animals)