Specialised Cells and Stem Cells

Question 1

Outline the levels of organisation of a multicellular organism (in order). (F)

Answer 1

• specialised cells
• tissues
• organs
• organ systems
• organism

Question 2

Define the term “specialised”. (F)

Answer 2

Having particular structure to serve a specific function.

Question 3

Define the term “differentiation”. (F)

Answer 3

The process of a cell becoming differentiated. Involves the selective expression of genes in a cell’s genome.

Question 4

Define the term “cell”. (F)

Answer 4

The basic unit of life.

Question 5

Define the term “tissue”. (F)

Answer 5

A collection of specialised cells that perform a particular function or functions.

Question 6

Define the term “organ”. (F)

Answer 6

A collection of tissues that perform a particular function in an organism.

Question 7

Define the term “organ system”. (F)

Answer 7

A collection of organs that perform a particular function in an organism.

Question 8

Explain why multicellular organisms have specialised cells.

Answer 8

• can divide labour between cells

- more efficient overall

Question 9

Describe the structure of erythrocytes and link to their function. (F)

Answer 9

Transport oxygen around the body.

• flattened biconcave shape to increase SA:V: can carry more haemoglobin
• lack nuclei and many other organelles: more space for haemoglobin
• flexible: can squeeze through capillaries

Question 10

Describe the structure of neutrophils and link to their function. (F)

Answer 10

Essential in immune system.

• multi-lobed nucleus: easier to squeeze through gaps to access site of infection
• granular cytoplasm contains many lysosomes: contain enzymes that attack pathogens

Question 11

Describe the structure of sperm cells and link to their function. (F)

Answer 11

Deliver genetic information to the female gamete.

• tail/flagellum: capable of movement
• many mitochondria: energy for swimming
• acrosome on head contains digestive enzymes: digest protective layers on egg for penetration and fertilisation

Question 12

Describe the structure of palisade cells and link to their function. (F)

Answer 12

Absorb light for photosynthesis.

• many chloroplasts: absorb lots of light
• rectangular box shape: closely packed to form a continuous layer
• thin cell walls: increase rate of diffusion of carbon dioxide
• large vacuole: maintain turgor pressure to keep its shape
• mobile chloroplasts: can absorb more light

Question 13

Describe the structure of root hair cells and link to their function. (F)

Answer 13

Absorb mineral ions and water from soil.

• root hair extensions: increase SA of cell to maximise water and mineral ion uptake from soil

Question 14

Describe the structure of guard cells and link to their function. (F)

Answer 14

Allow entry of carbon dioxide for photosynthesis.

• change shape when they lose water because of osmotic forces: close stoma to prevent further water loss
• cell wall is thicker on one side: bend outwards to open stomata

Question 15

State the 4 main categories of tissues in animals.

Answer 15

• nervous
• epithelial
• muscle
• connective

Question 16

State the adaptation of nervous tissue.

Answer 16

Support the transmission of electrical impulses.

Question 17

State the adaptation of epithelial tissue.

Answer 17

Cover body surfaces (internal and external)

Question 18

State the adaptation of muscle tissue.

Answer 18

Contract

Question 19

State the adaptation of connective tissue.

Answer 19

• hold other tissues together

- transport medium

Question 20

Describe the structure of squamous epithelium and link to its function. (F)

Answer 20

Present when rapid diffusion across a surface is essential i.e. lining of the lungs.

• very thin due to flat cells: rapid diffusion
• one cell thick: rapid diffusion

Question 21

Describe the structure of ciliated epithelium and link to its function. (F)

Answer 21

Removes unwanted particles.

• cilia on surface that move in a rhythmic manner: beat unwanted particles away from important areas
• goblet cells release mucus: trap unwanted particles and is swept away by cilia

Question 22

Describe the structure of cartilage and link to its function. (F)

Answer 22

Prevents the ends of bones rubbing together and causing damage i.e. in between bones.

• fibres of elastin and collagen: firm and flexible
• chondrocyte cells embedded in an extracellular matrix:

Question 23

Describe the structure of muscle and link to its function. (F)

Answer 23

Needs to contract in order to move bones and different parts of the body.

i. e. Skeletal Muscle
- myofibrils with contractile proteins: can contract

Question 24

State the 2 main categories of tissues in plants.

Answer 24

• epidermis

- vascular

Question 25

State the adaptation of epidermis tissue.

Answer 25

To cover plant surfaces.

Question 26

State the adaptation of vascular tissue.

Answer 26

Transport of water and nutrients.

Question 27

Describe the structure of the plant epidermis and link to its function. (F)

Answer 27

Protects the plant. - closely packed cells: prevent pathogen entry - waxy, waterproof cuticle: reduce water loss - stomata that can open and close: allow carbon dioxide, water vapour and oxygen to enter and exit the plant.

Question 28

Describe the structure of the xylem tissue and link to its function. (F)

Answer 28

Transport of water and minerals throughout plants. - parenchyma cells - xylem vessel - pits: water entry and exit - strengthened with lignin: provide structural support for plats

Question 29

Describe the structure of the phloem tissue and link to its function. (F)

Answer 29

Transport of organic nutrients from leaves and stems to areas of plant that require it. - sieve tube cells: allow movement of nutrients - companion cells: keep sieve tube elements alive - sieve plates: allow movement of nutrients

Question 30

State an example of an organ from an animal and outline its function and structure.

Answer 30

- heart - pumps blood around the body - muscle and connective tissue

Question 31

State an example of an organ from a plant and outline its function and structure.

Answer 31

- leaf - photosynthesis - epidermal and vascular tissue

Question 32

Describe the function of the digestive system.

Answer 32

- takes in food - breaks down large insoluble molecules into small soluble molecules - retains water - removes undigested material

Question 33

Describe the function of the cardiovascular system.

Answer 33

- moves blood around the body | - transport system for substances in blood

Question 34

Describe the function of the gaseous exchange system.

Answer 34

- brings air into body - oxygen extraction for respiration - carbon dioxide removal

Question 35

State 3 examples of organ systems in animals.

Answer 35

- digestive - cardiovascular - gaseous exchange

Question 36

Define the term “stem cell”. (F)

Answer 36

Undifferentiated cells with the potential to differentiate into a variety of the specialised cell types of the organism.

Question 37

Define the term “undifferentiated”. (F)

Answer 37

An unspecialised cell originating from mitosis or meiosis.

Question 38

Define the term “totipotent". (F)

Answer 38

A stem cell that can differentiate into any type of cell and form a whole organism.

Question 39

Define the term “pluripotent”. (F)

Answer 39

A stem cell that can differentiate into any type of cell, but not form a whole organism.

Question 40

Define the term “multipotent”.(F)

Answer 40

A stem cell that can only differentiate into a range of cell types within a certain type of tissue.

Question 41

Define the term “embryonic stem cell”. (F)

Answer 41

A stem cell found in an embryo. When it is a zygote, it is totipotent. When a blastocyst is formed (8 cells), it is pluripotent.

Question 42

Define the term “tissue (or adult) stem cell”. (F)

Answer 42

A stem cell found after birth, which is multipotent but may be artificially triggered to become pluripotent.

Question 43

Describe the characteristic abilities of stem cells as compared to specialised cells.

Answer 43

- can differentiate into any type of cell | - unspecialised