Biology - Mitosis and SA:V Ratio

What is diffusion in cells?

Diffusion is a passive transport process where small, nonpolar molecules move directly through the semipermeable phospholipid bilayer from high to low concentration, without using energy.

Which molecules commonly diffuse in plants and why?

Gases like carbon dioxide and oxygen diffuse in plants. CO₂ enters for photosynthesis, and O₂ exits as a waste product.

Why is a high surface area to volume ratio important for cells?

It allows substances like CO₂ and O₂ to diffuse efficiently, meeting the cell’s needs and removing waste quickly.

What happens when a cell’s volume becomes too large compared to its surface area?

Diffusion becomes too slow to supply nutrients and remove waste, potentially disrupting homeostasis.

How can cells increase surface area to improve diffusion?

Cells can form extensions (like microvilli) or folds in their membranes.

What is the role of cell division in maintaining efficient diffusion?

When a cell grows too large, it may divide via mitosis to restore an optimal surface area to volume ratio.

When are cell division rates high in animals?

During growth, in tissues with high diffusion demand (skin, digestive tract), and during repair (e.g., wound healing).

When are cell division rates high in plants?

In regions of growth, such as meristems or developing leaves and roots, to maintain efficient diffusion and grow structures quickly.

How does diffusion relate to homeostasis in cells?

Efficient diffusion ensures cells get enough nutrients, remove waste, and maintain stable internal conditions.

Maintaining stable internal conditions in a cell or organism, aided by efficient diffusion.

Homeostasis

Diffusion Distance

The length a molecule must travel to reach its destination; shorter distances make diffusion more efficient.

Exchange Surface

The part of a cell or organ where substances move in and out, optimized to increase SA:V for faster diffusion.