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 are some examples of specialised animal cells?

Answer 2

• Erythrocytes
• Neutrophils
• Sperm cells

Question 3

How are erythrocytes adapted for their function?

Answer 3

• Have a flattened biconcave shape which increases their surface area to volume ratio
• No nucleus to maximise space for haemoglobin
• Flexible so they are able to squeeze through capillaries

Question 4

How are neutrophils adapted for their function and what is their role?

Answer 4

• Multi-lobed nucleus which allows them to squeeze through small gaps to a site of infection
• Granular cytoplasm contains many lysosomes that contain enzymes used to attack pathogens
• Role:

Question 5

How are sperm cells adapted for their function?

Answer 5

• Tail or flagellum to allow them to move
• Many mitochondria to supply energy needed to move the flagella
• Head of sperm contains enzymes which are released to digest the protective layers around the ovum, allowing the sperm to penetrate, leading to fertilisation

Question 6

What are some examples of specialised plant cells?

Answer 6

• Palisade cells
• Root hair cells
• Guard cells

Question 7

How are palisade cells adapted for their function?

Answer 7

• Rectangular shape so they can be closely packed in to form a continuous layer
• Thin cell walls, increasing rate of diffusion of carbon dioxide
• Large vacuole to maintain turgor pressure
• Chloroplasts can move within the cytoplasm in order to absorb more light

Question 8

How are root hair cells adapted for their function?

Answer 8

• Long extensions called root hairs which increase surface area
• This maximises the uptake of water and minerals

Question 9

How are guard cells adapted for their function?

Answer 9

• Cell wall is thicker on one side so the cell does not change shape symmetrically as the volume changes
• When they lose water and become less swollen, as a result of osmotic forces, they change shape and stoma closes to prevent further water loss
• Necessary for carbon dioxide to enter

Question 10

What are the four mains categories of tissues in animals?

Answer 10

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

Question 11

What does squamous epithelial look like?

Answer 11

Very flat

Question 12

Why is squamous epithelial tissue flat?

Answer 12

Due to the flat cells that make it up and also because it is only one cell thick

Question 13

Where is squamous epithelial tissue found and why?

Answer 13

• Present when rapid diffusion across a surface is essential

- For example lining of lungs as it allows rapid diffusion of oxygen into the blood (only one cell thick)

Question 14

What does ciliated epithelium look like?

Answer 14

-Made up of ciliated epithelial cells that have ‘hair-like’ structures called cilia on one surface that waft

Question 15

Where is ciliated epithelium found and why?

Answer 15

• Lines the trachea
• Causes pathogens that have been trapped by mucus to be wafted away from the lungs
• Prevents infection

Question 16

What is cartilage?

Answer 16

Connective tissue found in outer ear, nose and at the ends and between of bones

Question 17

What does cartilage contain?

Answer 17

Fibres of the proteins elastin and collagen

Question 18

Why is cartilage important?

Answer 18

• Prevents ends of bones from rubbing together and causing damage
• Allows trachea to bend when food is swallowed
• Holds trachea open

Question 19

What does skeletal muscle contain?

Answer 19

Microfibrils which contain contractile proteins

Question 20

Why is muscle important?

Answer 20

Shortens in length, to move bones, which allows us to move different parts of the body

Question 21

What are the specialised plant tissues?

Answer 21

• Epidermis
• Xylem tissue
• Phloem tissue

Question 22

How is epidermis tissues adapted for its function?

Answer 22

Covered by a waxy, waterproof cuticle to reduce the loss of water by evaporation
Contains guard cells to allow carbon dioxide to diffuse in and out
Single layer so thin for diffusion

Question 23

What is epidermis made up of?

Answer 23

Single layers of closely packed cells covering the surfaces of plants

Question 24

How is xylem tissue adapted for its function?

Answer 24

Strengthened with waterproof material called lignin which provides structural support and prevents water loss
Elongated dead cell vessels to allow constant flow

Question 25

What kind of tissue is xylem tissue?

Answer 25

Vascular tissue

Question 26

What is xylem tissue responsible for?

Answer 26

Transport of water and minerals throughout plants

Question 27

What is phloem tissue responsible for?

Answer 27

Transport of organic nutrients, particular sucrose, from leaves and stems where it is made by photosynthesis to all parts of plant where it is needed

Question 28

What is phloem tissue composed of?

Answer 28

Sieve tube elements separated by perforated walls called sieve elements

Question 29

What is an organ?

Answer 29

Collection of tissue that are adapted to perform a particular function

Question 30

What are the organ systems?

Answer 30

• Digestive system
• Cardiovascular system
• Gas exchange system