BIOLOGY
HORMONES
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the nights are the right length
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the days are the right length
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a certain number of days have passed since they last flowered
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the soil reaches a certain temperature
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Detailed explanation-1: -night (out of 24 hours) that will cause a short day plant to flower. If the night length is 16 continuous hours, the critical length, the plant will flower.
Detailed explanation-2: -These are termed “long-day” plants. These bloom only when they receive more than 12 hours of light. Many of our summer-blooming flowers and garden vegetables are long-day plants, such as asters, coneflowers, California poppies, lettuce, spinach and potatoes.
Detailed explanation-3: -Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in plants and animals. Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods.
Detailed explanation-4: -It has long been known that plants use an internal time-keeping mechanism known as the circadian clock to measure changes in day length. Circadian clocks synchronize biological processes during 24-hour periods in people, animals, insects, plants and other organisms.
Detailed explanation-5: -Short-day plants form flowers only when day length is less than about 12 hours. Many spring-and fall-flowering plants are short-day plants, including chrysanthemums, poinsettias and Christmas cactus.