Cuz they are, ok
The thin bony columns in spongy bones are called trabeculae. They provide structural support and help distribute forces within the bone. Trabeculae also contain bone marrow, where blood cells are produced.
Because it contains air spaces which help regulate gas exchange in leaves and because most of the chloroplast are located in the palisade layer, it is here where the photosynthesis mainly takes place.
Underwater plants have long and thin leaves because they need to minimize resistance to water flow and reduce breakage from water currents. Broad leaves would create more drag and could be easily damaged. The thin leaves help optimize their ability to absorb sunlight and nutrients from the water.
Spongy bones contain what is called cancellous tissue, which is bone with a spongy or honeycomb appearance. This is where new blood cells are made.This cancellous bone framework is called the erythropoietic framework because it makes new blood cells.
Mesophyll tissue forms the bulk of the leaf. It makes up the green tissue of the leaf and consists of thin-walled cells containing chloroplasts (bits that contain the chlorphyll). In most dicot plants, the mesophyll is differentiated into palisade parenchyma and spongy parenchyma. The palisade parenchyma consists of thin-walled cells which are usually cylindrical. These cells contain large numbers of chloroplasts - the organelle used for capturing light and subsequesnt photosysnthesis.The spongy prenchyma, however, contains far fewer chloroplasts, so its main function is not photosynthesis. The spongy parenchyma has an open and net-like structure with large inter-cellular spaces that facilitate gas diffusion. The major function of the spongy parenchyma is the transport of oxygen, carbon-dioxyde and water vapour. It also is involved in the transport of water and the products of photosynthesis, the sugars. The spongy parenchyma is in close connection with the vascular bundles and the palisade parenchyma. When no clear differentiation exists between palisade and spongy parenchyma, the tissue is called mesophyll.Read more: http://wiki.answers.com/Why_is_the_palisade_layer_where_most_photosynthesis_occur#ixzz18UOwDLzu
Spongy bone looks like what a sponge looks like. It has many openings and a thin covering of hard bone over it.
The thin bony columns in spongy bones are called trabeculae. They provide structural support and help distribute forces within the bone. Trabeculae also contain bone marrow, where blood cells are produced.
Because it contains air spaces which help regulate gas exchange in leaves and because most of the chloroplast are located in the palisade layer, it is here where the photosynthesis mainly takes place.
take in water
A dildi
a fern
They grow.
Underwater plants have long and thin leaves because they need to minimize resistance to water flow and reduce breakage from water currents. Broad leaves would create more drag and could be easily damaged. The thin leaves help optimize their ability to absorb sunlight and nutrients from the water.
spongy bone tissue
Moss plants have small, flat, thin leaves
spongy (bone tissue)
I thin i is a tree what as lots of leaves.