2.1.6 - Cell division (set C - specialised cells)

Question 1

What does it mean if a cell is differentiated?

Answer 1

They are specialised to carry out very specific functions

Question 2

Explain what erythrocytes are and how they are specialised?

Answer 2

Red blood cells which have a flattened bio cave shape, which increases their surface area to volume ratio (essential for transporting oxygen) the cells have no nuclei in mammals to increase space for haemogolobin (molecule that carries oxygen)

• flexible so they can squeeze threw capilarries

Question 3

Explain what neutrophils are and how they are specialised?

Answer 3

Type of white blood cell involved in the immune system, have a characteristic multi-lobed nucleus which makes it easer to squeeze through small gaps to get to sites of infection

• granular cytoplasm contains many lysosomes (containing enzymes to attack pathogens)

Question 4

Explain what sperm cells are and how they are specialised?

Answer 4

Male gametes which function is to deliver genetic information to female gametes - they have a flagellum (tail) so they are capable of movement and contain many mitchondria to supply energy for swimming

• acrosome on the head contains digestive enzyme - allowing the sperm to penetrate the egg

Question 5

Explain what palisade cells are and how they are specialised?

Answer 5

Present in the mesophyll, they contain chloroplast capable of movement to absorb maximum light - cells are rectangular box shaped and closely packed to form a continuous layer - with large vacuole (maintains turgor pressure)

• have thin cell walls to increase diffusion of carbon dioxide

Question 6

Explain what root hair cells are and how they are specialised?

Answer 6

Present at the surface of roots (near the growing tips) they have long extensions (root hairs) which increase the SA maximising uptake of water and minerals from the soil

Question 7

Explain what guard cells are and how they are specialised?

Answer 7

Pairs of guard cells on the surface of leaves form small openings (stomata) - when guard cells loose water and become less swollen (due to osmotic forces) they change shape, preventing further water loss

• cell wall of guard cell is thicker on one side - so cell doesn’t change shape symmetrically

Question 8

Define a tissue?

Answer 8

A tissue is made up of a collection of differentiated cells that have a specialised function or functions - each tissue is adapted for a particular function within the organism

Question 9

Give the 4 main categories of tissues in animals?

Answer 9

• nervous tissue - adapted to support transmission of electrical impulses
• epithelial tissue - covers internal and external surface
• muscle tissue - adapted to contract
• connective tissue - holds other tissues together or as a transport medium

Question 10

Explain what the specialised animal tissue ‘squamous epithelium’ is and its structure?

Answer 10

Made up of specialised squamous epithelial cells, has a flat appearance and is very thin due to it being made up by single flat cells

• present when rapid diffusion across a surface is essential - forms the lining of the lungs

Question 11

Explain what the specialised animal tissue ‘ciliated epithelium’ is and its structure?

Answer 11

Made up of ciliated epithelial cells which have ‘hair-like’ structures called cilia on one surface which move in a rhythmic manner, important for sweeping and wafting mucus away in the trachea

• goblet cells are also present - releasing mucus - ciliated epithelium line the trachea

Question 12

Explain what the specialised animal tissue ‘cartilage’ is and its structure?

Answer 12

A firm, flexible connective tissue composed of chondrocyte cells embedded in an extracellular matrix - found in the outer ear, nose and at the ends and between bones (prevents rubbing and damage)

• it contains fibres of the protein elastin and collagen

Question 13

Explain what the specialised animal tissue ‘muscle’ is and its structure?

Answer 13

A tissue which is able to shorten in length (contract) in order to move bones - there are different types of muscle fibres

skeletal muscle fibres contain myofibrils which contain contractile proteins

Question 14

Give the names of 4 specialised animal tissues?

Answer 14

• squamous epithelium
• ciliated epithelium
• cartilage
• muscle

Question 15

Give two different types of tissues in plants - state what their adapted from?

Answer 15

• epidermis tissue - adapted to cover plant surfaces
• vascular tissue - adapted for transport of water and nutrients

Question 16

Give the name of 3 specialised plant tissues?

Answer 16

• epidermis
• xylem tissue
• phloem tissue

Question 17

State what the epidermis of plants is and its structure?

Answer 17

Single layer of closely packed cell which cover the surface of plants, they have stomata present which allows carbon dioxide in and out and water vapour and oxygen in and out

• usually covered by a waxy, waterproof cuticle which reduced water loss

Question 18

State what the xylem tissue of plants is and its structure - give the type of tissue?

Answer 18

Type of vascular tissue responsible for transport of water and minerals

• composed of vessel elements, which are elongated dead cells - the walls of the cells are strengthened with a waterproof material lignin providing structural support to the plant

Question 19

State what the phloem tissue of plants is and its structure?

Answer 19

Another type of vascular tissue in plants, responsible for the transport of organic nutrients particularly sucrose

• composed of columns of sieve tube cells separated by perforated walls called sieve plates

Question 20

Define an organ?

Answer 20

A collection of tissues that are adapted to perform a particular function in an organism - for example the mammalian heart is made up of muscle tissue and connective tissue

Question 21

Define an organ system - give an example?

Answer 21

Each organ is composed of an number of organs working together to carry out a major function in the body

Eg the digestive system which takes in food, breaks down large insoluble molecules into soluble molecules which are absorbed into the blood

Question 22

Explain what epithelial cells are and how they are adapted?

Answer 22

• Cover surface of organs
• cells joined by interlinking cell membranes and a membrane at their base
• some have cilia (eg ciliated epithelial cells in trachea) others are very thin for diffusion (squamous epithelial)

Question 23

Give two examples of organs and name the tissues that make them up?

Answer 23

• the lungs - contains squamous epithelia tissue (in alveoli) and ciliated epithelial tissue (in bronchi) - also have elastic connective tissue
• leaves - contain palisade tissue for photosynthesis as well as epidermal tissue and xylem and phloem tissue in the veins