Mr Khan had the following information to reflect on your project and your ideas on photosynthesis:

Trees grow larger primarily through a process of cell division and elongation, which involves the following key steps:

1. Cell Division: Trees, like all plants, start their growth by undergoing cell division in specific areas known as meristems. Apical meristems are found at the tips of branches and roots, while lateral meristems (cambium) are located in the vascular system, beneath the bark. These meristematic cells continuously divide, leading to the formation of new cells.

2. Cell Elongation: Once new cells are produced, they elongate or expand in size. This elongation occurs mainly in the regions just behind the tips of branches and roots, where cells differentiate into different types (e.g., xylem for water transport, phloem for nutrient transport, and various structural cells).

3. Vascular Tissue Development: The continuous activity of the cambium, which is a lateral meristem, results in the growth of vascular tissues such as xylem and phloem. Xylem transports water and nutrients from the roots to the rest of the tree, while phloem moves the products of photosynthesis (sugars) throughout the tree.

4. Bark Formation: The outermost layer of the tree, called the bark, also expands as the tree grows. The bark serves as a protective covering for the tree.

5. Height Growth: The apical meristem at the top of the tree is responsible for its vertical growth. As these cells divide and elongate, the tree increases in height.

6. Diameter Growth: The lateral meristems, especially the cambium, are responsible for the increase in trunk diameter. The cambium produces new xylem and phloem cells, pushing older layers outward, resulting in the growth rings seen in tree trunks.

7. Branch Formation: New branches and leaves develop from buds located at the axils of existing leaves or at the tips of branches. This branching contributes to the overall size and shape of the tree.

The combination of these processes allows trees to grow larger over time. The rate of growth and the eventual size of a tree depend on various factors, including species, environmental conditions, availability of resources (such as sunlight, water, and nutrients), and genetic factors. Trees can continue to grow larger for many years, often for centuries, depending on these factors.

The red tinge in trees, especially during the fall, is primarily due to a group of pigments called anthocyanins. Anthocyanins are water-soluble flavonoid pigments that are responsible for various shades of red, purple, and blue in plants, including trees.

Here's how anthocyanins contribute to the red coloration in trees:

1. Leaf Senescence: As the days grow shorter and temperatures drop in the autumn, deciduous trees prepare for the winter months by ceasing chlorophyll production in their leaves. Chlorophyll is the green pigment that is responsible for photosynthesis and the green color of leaves during the growing season.

2. Degradation of Chlorophyll: When chlorophyll breaks down and is no longer produced, other pigments in the leaves become more visible. As chlorophyll degrades and fades away, the yellow and orange pigments (carotenoids) that were already present in the leaves become visible. These pigments are responsible for the yellow and orange colors in autumn foliage.

3. Anthocyanin Production: Some tree species, especially certain maples, oaks, and dogwoods, also produce anthocyanins in response to environmental cues. These anthocyanins are produced in the presence of light and cooler temperatures. The red tinge in leaves is a result of anthocyanin accumulation in leaf cells.

4. Anthocyanin Role: The exact biological role of anthocyanins in trees is not fully understood, but they are believed to serve a protective function. Some hypotheses suggest that anthocyanins may help protect leaves from damage caused by excess light, cold temperatures, or various stressors. They may also act as antioxidants, scavenging harmful free radicals.

5. Variability: The intensity of red coloration can vary among different tree species and even among individual trees of the same species. It depends on factors like genetics, environmental conditions, and the specific types and concentrations of anthocyanins in the leaves.

As a result, the presence and intensity of the red tinge in tree leaves during the fall vary depending on the tree species, its individual characteristics, and the local environmental conditions. The combination of anthocyanin production, carotenoid presence, and chlorophyll breakdown creates the vibrant autumn foliage colors that are often associated with red, orange, and yellow hues.

Hi Planting Science teams! My name is Mindy Findlater and I am the scientist liaison working with your teacher and the mentors for you and your classmates. I am a teaching professor in biology at a school in California (UC Merced), and my favorite parts of biology are plants, genetics, and anything related to DNA. Outside of bio, I like exploring California (the ocean is my favorite part), watching hockey and football, and hiking.

It has been great to see you all get started on your projects! Please keep the updates coming, and also remember that you can choose a team name and image and add information to your "Info" section (the part at the top of your Updates page) as you design your projects. We are excited to see what you work on next!

Hi Planting Science teams! My name is Mindy Findlater and I am the scientist liaison working with your teacher and the mentors for you and your classmates. I am a teaching professor in biology at a school in California (UC Merced), and my favorite parts of biology are plants, genetics, and anything related to DNA. Outside of bio, I like exploring California (the ocean is my favorite part), watching hockey and football, and hiking.

It has been great to see you all get started on your projects! Please keep the updates coming, and also remember that you can choose a team name and image and add information to your "Info" section (the part at the top of your Updates page) as you design your projects. We are excited to see what you work on next!