6.4. ORGANISATION AND SPECIALISATION OF CELLS

Question 1

What are the levels of organisation in multicellular organisms?

Answer 1

specialised cells –> tissues –> organs –> organ systems –> whole organism

Question 2

What is a specialised cell?

Answer 2

• cells within an organism are differentiated
• specialised to carry out very specific functions

Question 3

What are Erythrocytes and how are they specialised (animal cells)?

Answer 3

• red blood cells
• flattened biconcave shape, increasing SA:V ratio
• no nuclei or many organelles, increases space available for haemoglobin (molecule that carries oxygen)
• flexible, can squeeze through narrow capillaries

Question 4

What are Neutrophils and how are they specialised (animal cells)?

Answer 4

• type of white blood cell that play a role in the immune system
• multi-lobed nucleus, easier to squeeze through small gaps to get to site of infections
• granular cytoplasm contains many lysosomes, contains enzymes used to attack to attack pathogen

Question 5

What are sperm cells and how are they specialised (animal cells)?

Answer 5

• male gametes that deliver genetic information to female gamete (egg/ ovum)
• tail/ flagellum, so are capable of movement and contain mitochondria to supply energy needed to swim
• acrosome on head contains digestive enzymes, released to digest protective layers around ovum and allow sperm to penetrate, leading to fertilisation

Question 6

What are palisade cells and how are they specialised (plant cells)?

Answer 6

• present in the mesophyll
• contain chloroplasts (that can move) to absorb large amounts of light for photosynthesis
• rectangular box shapes, can pack closely to form a continuous layer
• thin cell walls, increases rate of diffusion of C02
• large vacuole, maintain turgor pressure

Question 7

What are root hair cells and how are they specialised (plant cells)?

Answer 7

-present at the surface of roots near growing tips
- long extensions called root hair, increase SA of the cell
- increased SA maximises uptake of water and minerals from the soil

Question 8

What are guard cells and how are they specialised (plant cells)?

Answer 8

• pairs of these on the surface of leaves form stomata necessary for CO2 to enter plants for photosynthesis
• when guard cells lose water and become less swollen due to osmosis, they change shape and stoma closes to prevent further water loss
• cell wall is thicker on one side, cell does not change shape symmetrically as its volume changes

Question 9

What is a tissue?

Answer 9

• made up of a collection of differentiated cells that have a specialised function/s
• as a result, tissue is adapted to a particular function within the organism

Question 10

What are the four main categories of tissues in animals?

Answer 10

• nervous tissue
• epithelial tissue
• muscle tissue
• connective tissue

Question 11

What is nervous tissue adapted to?

Answer 11

• adapted to support transmission of electrical impulses

Question 12

What is epithelial tissue adapted to?

Answer 12

• adapted to cover body surfaces, internal and external

Question 13

What is muscle tissue adapted to?

Answer 13

• adapted to contract

Question 14

What is connective tissue adapted to?

Answer 14

• adapted either to hold other tissues together or as a transport medium

Question 15

What is Squamous epithelium tissue and how is it specialised (animal tissue)?

Answer 15

• made up of squamous epithelial cells (AKA pavement epithelium due to its flat appearance)
• very thin due to being made up of squat/ flat cells, as because it is only one cell thick
• present when rapid diffusion across a surface is essential
• forms the lining of the lungs and allows rapid diffusion of oxygen into the blood

Question 16

What is Ciliated epithelium tissue and how is it specialised (animal tissue)?

Answer 16

• made up of ciliated epithelial cells
• the cells have ‘hair-like’ structures called cilia on one surface that move in a rhythmic manner
• lines the trachea
• has goblet cells too, releases mucus to trap any unwanted particles present in the air

Question 17

What is cartilage tissue and how is it specialised (animal tissue)?

Answer 17

• connective tissue found in the outer ear, nose and at the ends of/between bones.
• firm, flexible and contains elastin and collagen, composed of chondrocyte cells embedded in the extracellular matrix
• prevents the ends of bones from rubbing together and causing damage
• many fish have whole skeletons made put of cartilage, not bone

Question 18

What is muscle tissue and how is it specialised (animal tissue)?

Answer 18

• needs to be able to shorten in length (contract) in order to move bones, which in turn move the different parts of the body
• different types of muscle cells, such as skeletal muscle fibres (attached to bone) containing myofibrils which contain contractile proteins

Question 19

What are the different tissues in plants?

Answer 19

• epidermis tissue
• vascular tissue

Question 20

What is vascular tissue adapted to?

Answer 20

• adapted for transport of water and nutrients

Question 21

What is the epidermis and how is it specialised (plant tissue)?

Answer 21

• single layer of closely packed cells covering the surfaces of plants
• covered by a waxy waterproof cuticle, reduce loss of water
• stomata are present in the epidermis, allowing CO2, O2 and water vapour in and out

Question 22

What is the xylem tissue and how is it specialised (plant tissue)?

Answer 22

• type of vascular tissue responsible for transport of water and minerals throughout plants
• composed of vessel elements, which are elongated dead cells
• cell walls are strengthened with a waterproof material called lignin, provide structural support

Question 23

What is the phloem tissue and how is it specialised (plant tissue)?

Answer 23

• another type of vascular tissue in plants, responsible for transport of organic nutrients, particularly sucrose, from leaves to stems where it is made by photosynthesis to all parts of the plant where it is needed
• composed of columns of sieve tube cells separated by perforated walls called sieve plates

Question 24

What is an organ?

Answer 24

• collection of tissues that are adapted to perform a particular function in an organism
• e.g. leaf is an organ in plants made up of vascular and epidermis tissues
• e.g. heart is an organ in animals made up of muscle and connective tissues

Question 25

What is an organ system?

Answer 25

• composed of a number of organs working together to carry out a major function in the body
• large multicellular organisms have coordinated organ systems

Question 26

What are some examples of organ systems in animals?

Answer 26

• digestive system
• cardiovascular system
• gaseous exchange system

Question 27

What is the digestive system?

Answer 27

• takes in food, breaks down large insoluble molecules into small soluble ones
• absorbs nutrients into the blood
• retains water needed by the body and removes any undigested material from the body

Question 28

What is cardiovascular system?

Answer 28

• moves blood around the body to provide an effective transport system for the substances it carries

Question 29

What is the gaseous exchange system?

Answer 29

• brings air into the body so oxygen can be extracted for respiration, and CO2 can be expelled