OVERMUGGED 2024 S3 IP RGS Biology WA2 Revision - Worksheet

REVISION WA2 SEC 3 & SEC 4 KOVAN | BUKIT TIMAH | MARINE PARADE 87702540 OVERMUGGED@GMAIL.COM WWW.OVERMUGGED.COM FOLLOW US ON IG:

© OVERMUGGED | www.overmugged.com | 2024 1 UPPER SECONDARY IP BIOLOGY Cells, Homeostasis, Nervous System, Human Eye RGS S3 WA2 revision Name: Date: Specialised cells Cell Structure Function Red blood cell (Animal cell) Lack nucleus and other organelles Allows red blood cells to pack more haemoglobin per cell to transport oxygen more efficiently around the body Circular, biconcave shape  surface area to volume ratio for rapid diffusion of oxygen into or out of the cell Lack mitochondria To ensure red blood cells do not respire the oxygen they are meant to transport Intestinal epithelial cell (Animal cell) Surface of each epithelial cell covered in small projections called microvilli  surface area to volume ratio for efficient absorption of nutrients Root hair cell (Plant cell) Long and narrow protrusion  surface area to volume ratio for efficient absorption of water and mineral salts No waxy cuticle, concentrated cell sap Provides a steep water potential gradient for greater rate of osmosis Contain numerous mitochondria Provides energy required for active transport of ions into the cell Xylem vessel (Plant cell) Long hollow tubes with no cross walls and protoplasm Continuous and smooth passage of water to transport water and mineral salts Lignin deposit on walls Supports the plant and prevents the vessel from collapsing

© OVERMUGGED | www.overmugged.com | 2024 2 The Nervous System The shortest pathway for nerve impulses to travel from receptor to effector is the reflex arc and explains why reflexes occur so quickly.

© OVERMUGGED | www.overmugged.com | 2024 3 The Human Eye The pupil constricts in bright light to reduce the amount of light entering the eye, protecting the retina from overstimulation. The pupil dilates in dim light to increase the amount of light entering the eye, enhancing dim light vision. The ciliary muscles and suspensory ligaments work together to change the shape of the lens, which increases or decreases the extent to which light rays are refracted. This fine adjustment allows the focal point to land directly on the retina for a clear image to form. A thinner and less convex lens refracts light to a smaller extent while a thicker and more convex lens refracts light to a greater extent.

© OVERMUGGED | www.overmugged.com | 2024 4 Homeostasis – thermoregulation Thermoreceptors in the skin detect changes in skin surface temperature while thermoreceptors in the hypothalamus detect changes in internal body temperature. Being in an extremely warm environment or consuming warm food and drinks will stimulate several corrective mechanisms to bring body temperature down towards the norm. On top of the aforementioned corrective mechanisms, metabolic rate decreases to reduce the rate of heat production. Breathi