Understanding Leaf Abscission in Evergreen Trees Quiz

1. When do evergreen trees lose their leaves?

Only in the winter

Steadily all year

Never at all

During the fall

Evergreen trees do not shed all their leaves at once in a specific season like deciduous trees do. Instead, they shed their leaves gradually throughout the year, hence the term 'steadily all year'.

Explanation

Evergreen trees do not shed all their leaves at once in a specific season like deciduous trees do. Instead, they shed their leaves gradually throughout the year, hence the term 'steadily all year'.

2. What pigments are revealed in a leaf when the breakdown of chlorophyll occurs?

Carotenoid

Xanthophyll

Anthocyanin

Phycobilin

When chlorophyll breaks down in a leaf, the carotenoid pigments are revealed, giving leaves their yellow, orange, and red hues.

Explanation

When chlorophyll breaks down in a leaf, the carotenoid pigments are revealed, giving leaves their yellow, orange, and red hues.

3. The formation of the abscission layer cuts off transport of substances to and from the leaf. As the concentration of sugar trapped within a leaf increases, ______ pigments are produced.

Anthocyanin

Carotenoid

Chlorophyll

Melanin

When a leaf is cut off from its supply of nutrients due to the formation of the abscission layer, anthocyanin pigments are produced as a response to the increased sugar concentration. These pigments contribute to the red, purple, and blue colors seen in some autumn leaves.

Explanation

When a leaf is cut off from its supply of nutrients due to the formation of the abscission layer, anthocyanin pigments are produced as a response to the increased sugar concentration. These pigments contribute to the red, purple, and blue colors seen in some autumn leaves.

4. What is the protective layer that forms between the abscission layer and the stem made up of?

Hollow cells filled with air

Dead cells lacking any structure

Transparent cells without any substance

Densely colored cells filled with a waxy layer

The protective layer that forms between the abscission layer and the stem consists of densely colored cells filled with a waxy layer, providing protection and support to the plant during detachment.

Explanation

The protective layer that forms between the abscission layer and the stem consists of densely colored cells filled with a waxy layer, providing protection and support to the plant during detachment.

5. After leaf abscission, growth will resume from the _____.

Apical bud

Root tip

Axillary bud

Stem node

After leaf abscission, growth resumes from the axillary bud located in the leaf axil, as it has the potential to develop into a new shoot or branch.

Explanation

After leaf abscission, growth resumes from the axillary bud located in the leaf axil, as it has the potential to develop into a new shoot or branch.

6. What type of trees lose their leaves in preparation for winter?

Coniferous

Palm

Deciduous

Evergreen

Deciduous trees shed their leaves annually in preparation for winter, while evergreen trees retain their leaves year-round. Coniferous trees are typically evergreen with needle-like or scale-like leaves. Palms are a type of tropical or subtropical tree which do not shed their leaves in preparation for winter.

Explanation

Deciduous trees shed their leaves annually in preparation for winter, while evergreen trees retain their leaves year-round. Coniferous trees are typically evergreen with needle-like or scale-like leaves. Palms are a type of tropical or subtropical tree which do not shed their leaves in preparation for winter.

7. For a short-day plant, the _____ is critical in determining if flowering will occur.

Minimum number of hours of darkness

Amount of sunlight received

Soil pH level

Maximum number of hours of darkness

The correct answer, 'minimum number of hours of darkness', refers to the specific requirement short-day plants have for a certain duration of darkness to trigger the flowering process. Short-day plants bloom when the period of darkness exceeds a critical length, unlike long-day plants which require shorter nights to flower. The incorrect answers provided are not directly related to the critical factor affecting flowering in short-day plants.

Explanation

The correct answer, 'minimum number of hours of darkness', refers to the specific requirement short-day plants have for a certain duration of darkness to trigger the flowering process. Short-day plants bloom when the period of darkness exceeds a critical length, unlike long-day plants which require shorter nights to flower. The incorrect answers provided are not directly related to the critical factor affecting flowering in short-day plants.

8. For a long-day plant, which factor is critical in determining if flowering will occur?

Temperature of the soil

Maximum number of hours of darkness

Amount of rainfall

Maximum number of hours of sunlight

The correct answer is the maximum number of hours of darkness because long-day plants require a certain period of uninterrupted darkness to initiate flowering.

Explanation

The correct answer is the maximum number of hours of darkness because long-day plants require a certain period of uninterrupted darkness to initiate flowering.

9. Day-neutral plants flower regardless of?

Humidity

Soil pH

Temperature

Day length, night length, or photoperiod

Day-neutral plants are not influenced by the length of the day or night, or photoperiod, when it comes to flowering. Other factors like temperature, soil pH, and humidity do not affect their flowering process.

Explanation

Day-neutral plants are not influenced by the length of the day or night, or photoperiod, when it comes to flowering. Other factors like temperature, soil pH, and humidity do not affect their flowering process.

10. Which of these would inhibit flowering in a short-day plant with a critical night length of 12 hours?

12 hours of light, 12 hours of dark

18 hours of light, 6 hours of dark

12 hours of light, 6 hours of dark, a flash of red light, 6 hours of dark

24 hours of continuous light

Short-day plants require a critical night length to initiate flowering. Any interruption or extension of the dark period will inhibit flowering. In this case, providing 24 hours of continuous light, 18 hours of light with only 6 hours of dark, or equal amounts of light and dark would not allow the short-day plant to flower as the critical uninterrupted dark period is not met.

Explanation

Short-day plants require a critical night length to initiate flowering. Any interruption or extension of the dark period will inhibit flowering. In this case, providing 24 hours of continuous light, 18 hours of light with only 6 hours of dark, or equal amounts of light and dark would not allow the short-day plant to flower as the critical uninterrupted dark period is not met.

11. Which of these would stimulate flowering in a long-day plant with a critical night length of 12 hours?

12 hours of light, 6 hours of dark, a flash of green light, 6 hours of dark

12 hours of light, 6 hours of dark, a flash of red light, 6 hours of dark

12 hours of light, 12 hours of dark, a flash of red light, 6 hours of dark

6 hours of light, 12 hours of dark, a flash of blue light, 6 hours of dark

In long-day plants, flowering is stimulated by short nights and long days. Providing 12 hours of light followed by 6 hours of darkness, along with a flash of red light during darkness, helps stimulate the flowering process.

Explanation

In long-day plants, flowering is stimulated by short nights and long days. Providing 12 hours of light followed by 6 hours of darkness, along with a flash of red light during darkness, helps stimulate the flowering process.