The Organisation And Specialisation Of Cells

Question 1

what is the basic unit of life?

Answer 1

cells

Question 2

what is the level of organisation of a multicellular organism?

Answer 2

1. specalised cells
2. tissues
3. organs
4. organ systems
5. organisms

Question 3

what does it mean for a cell to be differentiated?

Answer 3

they are specialised to carry out of specific function.

Question 4

what are some examples of specialised animal cells?

Answer 4

• erythrocytes
• neutrophils
• sperm cells

Question 5

how are erythrocyes specialised?

Answer 5

• flattened bioconcave shape - increases surface area to volume ratio.
• no nuclei which increases the space available for haemoglobin
• flexible so they can squeeze through narrow capillaries.

Question 6

how are neurtophils specialised?

Answer 6

• play an important role in the immune system.
• characteristic multi lobed nucleus which makes it easier to squeeze through small gaps to the site of infecion.
• granular cytoplasm contains many lysosomes containing lysozyme used to attack pathogens.

Question 7

how are sperm cells specialised?

Answer 7

• male gametes with function to deliver genetic information to female gamete, the ovum.
• tail/flagellum so they are capable of movement
• contain many mitochondria to supply the energy needed to swim.
• acrosome on the head of the sperm contains digestive enzymes which are released to digest the protective layers around the ovum and allow the sperm to penetrate.

Question 8

what are some examples of specialised plant cells?

Answer 8

• palisade cells
• root hair cells
• guard cells

Question 9

how are palisade cells specialised?

Answer 9

• present in the mesophyll
• contain chloroplasts to absorb large amounts of light for photosynthesis.
• rectangular box shapes which can be closely packed to form a continuous layer
• thin cell walls which increases the rate of diffusion of cabron dioxide.
• large vacuole to maintain turgor pressure.
• chloroplasts can move within the cytoplasm to absorb more light.

-

Question 10

how are root hair cells adapted to their functions?

Answer 10

• long extensions called root hairs which increases the surface area of the cell. this maximises the uptake of water and minerals from the soil.

Question 11

how are guard cells specialised?

Answer 11

• pairs of guard cells form stomata; necessary for carbon dioxide entering plants for photsynthesis.
• when guard cells lose water, they change shape and the stoma closes to prevent further water loss.
• cell wall of guard cell thicker on one side so the cell does not change shape symmetrically as its volume changes.

Question 12

what is a tissue?

Answer 12

made up of a collection of differentiated cells that have a specialised function.

Question 13

what are the four main catergories of tissues in animals?

Answer 13

• nervous tissue (support transmission of electrical impulses)
• epithelial tissue (adapted to cover body surfaces)
• muscle tissue (adapted to contract)
• connective tissue (adapted to hold tissues together )

Question 14

how is squamous epithelium a specialised tissue?

Answer 14

• made up of specialised squamous epithelial cells
• very thin due to flat cells that make up it.
• 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 15

how is ciliated epithelium a specialised tissue?

Answer 15

• made up of ciliated epithelial cells
• hair like structures called cilia on one surface that moves in a rythmic manner
• lines the trachea causing mucus to be swept away from the lungs.

Question 16

how is cartilage a specialised tissue?

Answer 16

• connective tissue found in ear, nose, and ends of bones.
• contains fibres of elastin and collagen.
• firm, flexible conntective tissue composed of chondrocyte cells embedded in an extracellular matrix.
• cartilage prevents the ends of bones rubbing together and causing damage.

Question 17

how is muscle a specialised tissue?

Answer 17

• tissue that needs to shorten in length in order to move bones.
• skeletal muscle fibres contain myofibrils which contain contractile proteins.

Question 18

what are the different tissues in plants?

Answer 18

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

Question 19

how is the epidermis a specialised tissue?

Answer 19

• single layer of closely packed cells covering surfaces of the plants
• usually covered by a waxy, waterproof cuticle to reduce the loss of water.
• stomata that can open and close are present in the epidermis, allowing carbon dioxide in and water vapour and oxygen out.

Question 20

how is xylem tissue a specialised tissue?

Answer 20

• type of vascular tissue responsible for transport of water and minerals throughout plants.
• tissue is comoposed of vessel elements, which are elongated dead cells.
• walls of cells are strengthened by lignin, providing structural support to plants.

Question 21

how is phloem tissue a specialised tissue?

Answer 21

• another type of vascular tissue
• responsible for transport of organic nutrients from leaves and stems where it is made by photosynthesis to all parts of the plant where it is needed.
• composed of columns of sieve tube cells sepereated by perforated walls called sieve plates.

Question 22

what is an organ?

Answer 22

a collection of tissues adapted to perform a particular function.

Question 23

what are some examples of organ systems in animals?

Answer 23

• the digestive system
• cardiovascular system
• gaseous exchange system