Specific excretory organs are absent in unicellular organisms belonging to the<u> phylum Porifera.</u>
The organisms of the phylum Porifera are classified under the kingdom Animalia and they lack specific organs in their bodies.
The word "Porifera" refers to pore-bearing organisms.
These animals have loosely organized cells and are found in freshwater marine ecosystems.
On their body, a large number of pores - Ostia - are present which perform various functions such as excretion.
However, respiratory gases and waste materials are exchanged through a diffusion process.
Moreover, in them, reproduction takes place through fragmentation and budding.
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Explanation:
1. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.
2. Cartilage is a connective tissue consisting of a dense matrix of collagen fibres and elastic fibres embedded in a rubbery ground substance. The matrix is produced by cells called chondroblasts, which become embedded in the matrix as chondrocytes. That is, mature cartilage cells are called chondrocytes.
3. Collagen is a part of the connective tissue that in the skin helps in firmness, suppleness and constant renewal of skin cells. Collagen is vital for skin elasticity.
Answer:
paired t-test
Explanation:
The paired t-test is used for samples or variables that belong to the same individual or entity under study. Recall that; if the experiment is to be carried out with each experiment unit being measured twice, then giving an outcome of pairs of observations; Hence, we apply the paired t-test.
Answer: c. bleeding, attachment loss, sulcus depth of >4 mm
Explanation:
Periodontitis is a serious infection of gum. It causes the damage of soft tissues and also destroy the bones that support the teeth.
This disease can cause loosening of teeth. But it is commonly preventable. It is because of poor hygiene of mouth. It results in bleeding of gums. It also results in decrease in depth of sulcus to 4mm.