Multicellular Organisms 3
Why are there small amounts of enzymes in a cell?
Enzymes can be continuously reused to catalyse reactions.
What is the part of an enzyme called that binds to a substrate to initiate a chemical reaction?
Active site
What is the purpose of villi and microvilli?
More opportunities for exchange of nutrients.
Where are proteins, carbohydrates, and lipids absorbed in the small intestine?
Lacteal - absorbs fatty acids and glycerol
Blood capillary - absorbs glucose and amino acids
Blood plasma vs filtrate in bowman's capsule
Blood plasma contains cells, proteins and big molecules where as filtrate does not. Filtrate will contain urea, glucose, salts and water.
What are the stages which occur in the kidneys?
Filtration and absorption
What is filtration?
A passive and non-selective process which removes unwanted material from the body as filtrate travels through the nephron.
What is reabsorption? What materials are reabsorbed?
Important substances which have been filtered out and reabsorbed back into the capillaries through active transport and osmosis. Susbtances reabsorbed include: glucose, amino acid, some ions. Process uses active transport and is selective.
How are water levels controlled in the body?
The kidneys regualte water in the body by controlling the excretion of water with urea in urine.
How is urea removed from the body?
Drain down the collecting duct to through the bladder and excreted from the body as urine.
What is the role of the kidneys?
Clean blood of waste products while controlling how much water is kept in the body.
Order that filtrate passes through the nephron:
efferent atriole - glomerulus - bowman's capsule - proximal tubule - loop of Henle - distal conveluted tubule - collecting duct
What is in filtrate?
water, glucose, amino acids and salts
What are the requirements of a plant? Where are these absorbed and stored?
Water, nutrients, minerals and sugar
Water, nutrients and minerals are taken in by roots.
Sugar is made in leaves.
What are the two types of tubes made from vascular tissue, capable of transporting these materials?
Xylem - responsible for movement of water, nutrients and minerals absorbed from soil through roots. The cells are tubular and elongated. (DEAD)
Pholem - composed of thin walled cells for transport of suagr from leaves to other parts of the body. (LIVE)
Function of roots
Absorb nutrients from soil, support and anchor plant while acting as storage.
What are the two types of roots?
Tap roots. These are deep in the ground present for trees and carrots.
Fibrous roots. These are shallow in the ground and present for grasses and colonisers.
How is water absorbed in plants?
Root hairs along the root's surface increase surface area, enters root from soil by osmosis as the difference in water pressure forces phloem sap from the source to the sink cells. Once entering the roots, becomes turgid, anchoring the plant so it stays upright.
Function of the root hairs along the root:
These are an extension of the root epidermal cells which can pentrate between soil particles, in close contact with soil and water.
How do minerals enter the plant?
Enter root from the soil by diffusion or active transport.
What is transpiration?
Accumulation of water in xylem vessels within root systems, creating root pressure with the upwards push forcing molcules of water upwards to the stem and leaves. The water molecules then move into air spaces of spongy mesophyll.
What is the role of the lymphatic system?
Acts as drainage system for removal of excess fluid from tissues, returning them to blood stream.
What is the lymphatic system made of?
One direction open network of vessels.
Blood plasma containing nutrients moves...
out of the atrieal end of capillary.
Tissue fluid with wastes...
reabsorbs back into blood.