6.4 Organisation And Specialisation Of Cells

Question 1

Levels of organisation in multicellular organism

Answer 1

Specialised cell > tissue > organs > organ system > whole organism

Question 2

Erythrocytes adaptation

Answer 2

Flattened biconcave shape - increase SA:V ratio
No nuclei - more space more haemoglobin
Flexible - squeeze through narrow blood capillaries
Thin membrane - short diffusion distance for oxygen

Question 3

Neutrophils

Answer 3

Play essential role in immune system
Multi lobed nucleus - easier to squeeze through gaps to get to infection sites
Granular cytoplasm - many lysosomes with enzymes to attack pathogens

Question 4

Sperm cells

Answer 4

Male gametes
Deliver genetic information to the female gamete
Sperm have a flagellum - to propel through body fluids
Many mitochondria - more energy to swim
Acrosome - head of sperm contains digestive enzymes (digest protective layers around ovum and allow sperm to penetrate causing fertilisation)

Question 5

Palisade cells

Answer 5

Contain chloroplasts to absorb large amounts of light for photosynthesis
Rectangular box shapes - closely packed to form a continuous layer
Thin walls - increase rate of CO2 diffusion
Large vacuole for maintain turgor pressure
Chloroplasts can move within the cytoplasm to absorb more light

Question 6

Root hair cells

Answer 6

Present at surfaces of roots near growing tips
Long extensions called root hairs - increase SA of cell
Maximises uptake of water and minerals from soil

Question 7

Guard cells

Answer 7

Pairs of guard cells control opening and closing of stomata
When guard cells lose water and become less swollen, they change shape and stoma closes to prevent further water loss from plant
Cell wall of guard cell is thicker on one side, so cells do not change shape symmetrically as volume changes

Question 8

Tissue

Answer 8

Made of collection of differentiated cells that have specialised functions

Question 9

4 types of tissues

Answer 9

Nervous - transmission of electrical impulses
Epithelial - adapted to cover body surfaces, internal and external
Muscle tissue - adapted to contract
Connective tissue - hold tissues together or as a transport medium

Question 10

Squamous epithelium

Answer 10

Made of specialised squamous epithelial cells
Very thin due to square flat cells - only one cell thick
Required for rapid diffusion across a surface
Forms lining of lungs and allows rapid diffusion of O2 into the blood

Question 11

Ciliated epithelium

Answer 11

Made of ciliated epithelial cells
Hair like structures - cilia that move in a rhythmic manner
Line the trachea to waft away mucus from lungs
Goblet cells also present, release mucus to trap particles

Question 12

Cartilage

Answer 12

Connective tissue
Found in outer ear, nose and between bones
Contains fibres of elastin and collagen
Composed of chondrocyte cells embedded in extra cellular matrix
Prevents ends of bones rubbing together and causing damage

Question 13

Muscle

Answer 13

Tissues that shortens in length to move bones which in turn move different parts of the body
Skeletal muscle fibres (attached to bone) contain myofibrils that have contractile proteins

Question 14

Different tissues in pants

Answer 14

Epidermis - adapted to cover plant surfaces

Vascular - adapted for transport of water and nutrients

Question 15

Epidermis

Answer 15

Single layer of closely packed cells covering surface of plants
Usually covered by waxy cuticle to reduce water loss
Stomata are found in the epidermis

Question 16

Xylem tissue

Answer 16

Vascular tissue
Transport of water and minerals around the plant
Composed of vessel elements (elongated dead cells)
Walls of these cells are strengthened with lignin, which is waterproof and provide structural support

Question 17

Phloem tissue

Answer 17

Vascular tissue
Transport organic nutrients, especially sucrose from leaves and stems to all parts of the plant where it is needed
Composed of sieve tube cells separated by perforated walls called sieve plates

Question 18

Organ

Answer 18

Collection of tissues adapted to perform a particular function in an organism

Question 19

Organ system

Answer 19

Composed of a number of organs working together to carry out a major function in the body

Question 20

Digestive system

Answer 20

Takes in food, breaks down larger insoluble molecules into small soluble ones
Absorbs nutrients in the blood, retains water needed by the body and removes undigested material from the body

Question 21

Cardiovascular system

Answer 21

Moves blood around the body to provide effective transport system for substances it carries

Question 22

Gaseous exchange system

Answer 22

Brings air into the body so oxygen can be extracted for respiration and carbon dioxide can be expelled