Biology: Photosynthesis and Plant Minerals

Photosynthesis

• Photosynthesis occurs within chloroplasts, found inside plant cells.
• Chloroplasts need sunlight, water, and carbon dioxide for photosynthesis.
• Plants store excess carbohydrates created during photosynthesis as starch within chloroplasts.
• Leaves are thin and have stomata, tiny holes allowing gas exchange for photosynthesis.
• Water travels through the plant's veins to reach the leaves for photosynthesis.

Plant Minerals

• Fertilizers contain minerals that plants need to grow.
• Plants absorb these minerals through their roots.
• Magnesium is vital for chlorophyll production, giving leaves their green color.
• Lack of magnesium results in yellowing leaves and reduced photosynthesis.
• Nitrate provides nitrogen, essential for converting carbohydrates into proteins.
• Insufficient nitrogen leads to stunted growth, leaf death, and reduced chlorophyll production.

Carbon Cycle

• Living organisms require carbon, but not in its elemental form.
• Plants obtain carbon from carbon dioxide in the air during photosynthesis to make carbohydrates.
• These carbohydrates are then used to create proteins and fats, which contain carbon.
• Animals obtain their carbon by consuming plants or other animals.
• Decomposers obtain carbon by breaking down plant and animal waste.

Carbon Dioxide Back to the Air

• Plants and animals release carbon dioxide through respiration.
• Decomposers also release carbon dioxide into the air during the breakdown of plant and animal waste.
• When organisms die in oxygen-deprived environments, they form fossil fuels like coal, oil, and natural gas over millions of years.
• Coal, formed from ancient plant matter, is used to generate electricity, releasing more carbon dioxide into the atmosphere.

Ice Ages and Climate Change

• The Earth has experienced numerous periods of cold (ice ages) and warm periods in its history.
• Asteroids colliding with Earth can trigger ice ages by blocking sunlight and causing global cooling.
• The collision that wiped out the dinosaurs 67 million years ago caused mass extinction due to changes in the climate and food chains.

Meteoroids and their Impacts

• Meteoroids are space objects smaller than asteroids that become meteors when entering Earth's atmosphere.
• Most meteors burn up due to friction with the atmosphere but can cause shockwaves if large enough.
• Meteorite fragments that reach Earth can cause local damage, especially if large.

Climate Change Impacts

• Increasing Earth's temperature affects sea levels, weather patterns, and ecosystems.
• Rising sea levels threaten coastal cities and displace populations.
• Frequent droughts increase the risk of wildfires and impact agriculture.
• Changing weather patterns affect plant and animal life, disrupting food chains.

Water's Importance in Life

• Water acts as a solvent, dissolving essential compounds for survival.
• Water has a high specific heat capacity, regulating internal temperatures and preventing enzyme damage.
• Water is a metabolite involved in vital chemical reactions within organisms, like photosynthesis.
• Water provides a living environment for aquatic organisms, allowing them to breathe dissolved oxygen.

Root Hairs and Water Absorption

• Root hairs are specialized cells on plant roots that increase the surface area for water absorption.
• Root hairs absorb water and dissolved minerals from the soil.
• Water and mineral ions move from the soil into the root hair cells through the cell wall and membrane.

Xylem Vessels

• Xylem vessels are specialized, dead cells that form long tubes transporting water from roots to the rest of the plant.
• Water moves from the root hair cells into the xylem vessels in the root's center.
• The empty tubes of stacked xylem vessels allow uninterrupted water flow throughout the plant.