chapter 1 - cell structure and organisms

Question 1

cell wall

Answer 1

protects the cell from injury and gives the plant cell a fixed shape

Question 2

cell membrane

Answer 2

partially permeable membrane which regulates the type of substances entering and exiting the cell

Question 3

cytoplasm

Answer 3

jelly-like substances where chemical reactions take place

Question 4

nucleus

Answer 4

contains hereditary information which controls cell activities and cell division

Question 5

cell vacuoles

Answer 5

• large, sap-filled in plant cells, small, temporary in animal cells
• used to store dissolved substances

Question 6

chloroplasts

Answer 6

contain a green pigment called chlorophyll to absorb light energy to produce glucose through photosynthesis

Question 7

SER

Answer 7

synthesis of fats and proteins + involved in detoxification

Question 8

RER

Answer 8

transports proteins made by ribosomes to golgi apparatus for secretion out of the cell

Question 9

golgi apparatus

Answer 9

chemically modifies, stores and packages substances made by ribosomes on RER and the SER into vesicles for secretion out of the cell

Question 10

mitochondria

Answer 10

site of aerobic respiration where glucose is oxidised in the presence of oxygen to release energy for cellular activities

Question 11

ribosomes

Answer 11

• attached onto RER
• synthesis of proteins

Question 12

how protein is synthesised and transported in the cell for secretion?

Answer 12

proteins synthesised by the ribosomes on the rough endoplasmic reticulum enter into the RER. the manufactured proteins are transported to the golgi apparatus. the golgi apparatus stores and chemically modifies the proteins made by RER and packages them in vesicles. the secretory vesicles containing the modified proteins are pinched off from the golgi apparatus. the vesicles the move towards the cell membrane and fuses with the membrane and releases the contents in the vesicles into the outside of the cell

Question 13

diffrences between typical animal and plant cells (name 3)

Answer 13

• plant cells have a cell wall but animal cell doesn’t
• plant cells have chloroplasts but animal cell doesn’t
• plant cells has a large central vacuole but animal cells have small and numerous vacuoles

Question 14

describe structure of root hair cells and how it helps them to adapt to their functions

Answer 14

• long and narrow protrusion to increase the SA2VR for faster absorption of water and mineral salts
• large central vacuole that is concentrated with mineral salts and sugars to maintain a steep gradient for faster absorption of water via osmosis
• presence of numerous mitochondria to release more energy during aerobic respiration for active transport of mineral salts

Question 15

describe structure of xylem vessels and how it helps them to adapt to their functions

Answer 15

• thick and lignified cell wall that provides mechanical support by strengthening the vessel and prevent the palnt from collapsing
• narrow, hollow, lumen with no cross well : for faster transportation of water and mineral salts from the roots to leaves

Question 16

describe structure of red blood cells and how it helps them to adapt to their functions

Answer 16

• contains haemoglobin that binds with oxygen to form oxyhaemoglobin to transport oxygen
• lack of nucleus to provide more space in the cytoplasm to carry more haemoglobin to bind with and transport more oxygen
• circular and biconcave shape to increase the SA2VR for faster diffusion of oxygen in and out of the cell
• flexible cell membrane to allow red blood cells to squeeze into narrow capillaries