cells

Question 1

cells

Answer 1

basic structural and functional units

unicellular/multicellular

Question 2

protoplasm

Answer 2

plasma membrane, cytoplasm, nucleus

Question 3

cell surface membrane/ plasma membrane

• present in all living cells
• surrounds the cytoplasm
• partially permeable membrane
• made up of lipids and proteins (double phospholid layer)

Answer 3

selective barrier that allows certain substances to pass through, controlling the exchange of substances between the cell and its environment

Question 4

cytoplasm

• colloidal; found in sol (liquid) or gel (semi-solid) state
• contains enzymes and cell organelles (specialized structures to carry out specific functions)
• most cell activities occur here (endless chemical reactions take place)

Answer 4

site where most cell activities and reaction occur

Question 5

nucleus

• nuclear envelope: a membrane which separates the contents of nucleus from the rest of the cytoplasm
• nucleoplasm: dense material within nucleus
• nucleolous: plays a part in making of proteins
• chromatin: genetic materials

Answer 5

controls cellular activities such as cell growth and repairing of worn-out parts
essential role in cell division

Question 6

chromatin

• network of long thread-like structures found within the nucleus
• each chromatin thread is made up of protein and deoxyribonucleic acid (DNA)

Answer 6

hereditary information is stored in DNA

DNA contains instructions a cell needs for carrying out all the chemical reaction within itself

Question 7

rough endoplasmic reticulum (RER)

• a network of membranes in the shape of flatted sacs/spaces, with ribosomes attached
• outer surface is continuous with the nuclear envelope

Answer 7

transport proteins synthesized by the ribosomes to the Golgi apparatus for secretion out of the cell

Question 8

smooth endoplasmic reticulum (SER)

• a network of membranes, without ribosomes attached
• more tubular than RER

Answer 8

synthesize fats and steriods (e.g. sex hormones)

involved in detoxification by converting harmful substances into harmless materials

Question 9

Golgi apparatus

• a stack of flattened spaces surrounded by membranes (disc-shaped)

Answer 9

chemically modifies substances made (mainly proteins) by endoplasmic reticulum
store and replaces substances (mainly proteins) made by endoplasmic reticulum into vesicles for secretion out of the cell
vesicles can be seen fusing with one side of the Golgi apparatus and pinching off from the opposite site

Question 10

mitochondria

• oval-shaped with highly intricate internal folds

Answer 10

site where aerobic respiration occurs to oxidise glucose to release large amount of energy
these energy are used by cells to perform cellular functions and activities

Question 11

ribosomes

• small round structures
• either found attached to the surface of RER or exists/ lie freely in the cytoplasm

Answer 11

synthesize proteins in the cell
ribosomes attached to RER synthesize proteins that will be transported out of the cell
- RER transport proteins (made by ribosomes) to the Golgi apparatus for secretion out of the cell
ribosomes lying freely in cytoplasm synthesize proteins to be used within cytoplasm of cell

Question 12

vacuole
(animal/plant)

• fluid-filed space enclosed by a membrane

Answer 12

(animal)
animal vacuoles contain water and nutrients. animal cells contain many small vacuoles that exist temporarily
(plant)
a large central vacuole that contains cell sap
cell sap in the plat vacuole contains dissolved sugar, mineral salts and amino acids and some water. Plant vacuoles are enclosed by tonoplast (a partially permeable membrane)

Question 13

cell wall

• on the outermost part of the cell
• made up of cellulose
• fully-permeable membrane
• non-living, not part of the living protoplasm
• rigid structure

Answer 13

protects the cell from from injury

provide mechanical support

Question 14

chloroplast

• oval structures which contains green pigment known as chlorophyll

Answer 14

chlorophyll is essential for photosynthesis to occur

Question 15

centrioles

• a pair of small, hollow cylinders near nucleus
• only found in animal cells

Answer 15

plays an important role in cell division

Question 16

red blood cell

(transport oxygen from lungs to all parts of the body

Answer 16

contains haemoglobin - binds reversibly to oxygen
no nucleus (contains more haemoglobin) - enables it to carry more oxygen
biconcave in shape (increases surface area to volume ratio) - allows efficient diffusion of oxygen into and out of the cell/ increase the rate of diffusion of oxygen

Question 17

root hair cell

absorbs water and mineral salts

Answer 17

has long and narrow protrusion/elongated (increases surface area to volume ratio) - efficient absorption of water and mineral salts

Question 18

xylem vessel

to transport water and mineral salts from roots to leaves

Answer 18

no cross walls/no protoplasm (reduces resistance to water flowing through xylem) - efficient conduction of water and minerals
cell walls are thickened with lignin - provide mechanical support to prevent the vessel from collapsing

Question 19

organelle

Answer 19

mitochondrion
RER
Golgi apparatus
ribosomes
chloroplast

Question 20

cell

Answer 20

red blood cell
nerve cell
guard cell

Question 21

tissue

Answer 21

simple tissue: muscle tissue

complex tissue: blood, nerve tissue, phloem tissue

Question 22

organ

Answer 22

skin
heart
leaf

Question 23

organ system

Answer 23

circulatory system

root system

Question 24

organism

Answer 24

human
bird
fish