Question

1. Plants and animals both circulate nutrients, hormones, and other necessary molecules through their systems. Compare and contrast the circulatory systems of plants and animals (you can pick a specific animal or keep it at a generic level). Include the physical nature of the circulation (what structures facilitate circulation), what substances circulate, and what structures/ processes control where those substances end up.

Answer 1

Circulatory system also known as cardiovascular in animals and vascular system in plants serves the main purpose of translocation of essential nutrients,exchange of gases at the tissue level and removal of waste products.The essential constituents of circulatory system in animals consists of blood,heart and blood vessels whereas in plants this comprises xylem and phloem primarily along with various other conducting Fibres and supportive tissues.

TRANSPORT OF GASES

Blood is the connective tissue which is involved in the transport of oxygen,carbon dioxide and their exchange at the tissue level.The exchange of gases between alveolar air and pulmonary blood is done by simple diffusion based on partial pressure of each gas.Carbon dioxide is transported as bicarbonate mainly.Carbon dioxide is generated in tissue and diffused freely into the venous plasma and into RBC.Oxygen is transported in the form of oxyhaemoglobin.

In plants Stomata are specialized epidermal structures that are responsible for gaseous exchange between plants and environment.Lenticels are also involved in same and account for nearly 1-5% of gaseous exchange.The exchange in plants is a result of Transpiration(loss of water in the form of water vapor).The guard cells,subsidiary cells and pore are called stomatal complex.Microfibrils present in guard cells assist opening of guard cells.

Transport of nutrients

The food digested is absorbed and circulated in the animals body through a vast Network of capillaries in the microvilli in small intestine and through blood.Each of the macromolecule needs to be broken down into small micromolecules so that they can be easily assimilated and absorbed.Fats move through in the form of bile micelles and glucose is transported with the help of GLUT transporter.Various amino acid transporters are also involves in movement of amino acids.Facilitated diffusion helps in the movement of charged molecules whereas simple diffusion for uncharged molecules.

In plants Roots is the primary structure for Absorption of nutrients and water.Aquaporin in one membrane transport protein which is involved in the movement of water molecules.Radial movement of water through roots takes place by Symplastic or Apoplastic pathway.Xylem is a complex tissue consisting of tracheids and vessels assisting in water and mineral transport.Tracheids are elongated whereas as vessels are shorter and wider.Sucrose which is the main sugar produced in plants are transported by phloem mainly due to difference in osmotic concentrations and pressure difference.Sucrose moves from sieve tubes to surrounding by active or passive transport.