C6 (Cell Division)

Question 1

Summary of Organisation of a multicellular organism can be summarised as..

Answer 1

Specialised cells, tissues, organs, organ systems, whole organism

Question 2

Specialised cells

Answer 2

Cells within multicellular organisms are differentiated/ specialised to carry a very specific function

Question 3

Erythrocytes

Answer 3

• Red blood cells
• Flattened biconcave shape (increased SA:V ratio)
• Essential to the role of transporting oxygen around body
• No nucleus or other organelles (increase space available for haemoglobin)
• Flexible, can squeeze through narrow capillaries

Question 4

Neutrophils

Answer 4

• Type of white blood cells, essential role immune system
• Multi-lobed nucleus, easier to squeeze through small gaps to get to site of infection
• Granulas cytoplasm, many lysosomes (contain enzymes to attack pathogens)

Question 5

Sperm cells

Answer 5

• Male gametes, deliver genetic info to female gamete
• Flagellum, capable of movement, many mitochondria for energy
• Acrosome contains digestive enzymes, digest protective layer around ovum.

Question 6

Palisade cells

Answer 6

Present in mesophyll, contain chloroplast for photosynthesis

• Rectangular box shape, can be closely packed to form continuous layers
• Thin cell walls, increasing rate of diffusion
• Large vacuole to maintain turgor pressure
• Chloroplasts can move within cytoplasm to absorb move light

Question 7

Root hair cells

Answer 7

Surfaces of roots near growing tips
Long extensions are called root hairs, increase SA
Maximises uptake of water and minerals from soil

Question 8

Guard cells

Answer 8

• Surfaces of leaves, from small opening called stomata
• When lose water, become less swollen and close to prevent water loss due to osmotic forces
• Cell wall thicker on one side, does not change symmetrically as vol changes

Question 9

Tissues

Answer 9

Made up of a collection of differentiated cells . Adapted for particular functions within organisms.

4 main categories of animal tissues:
-Nervous tissue, support transmission of electrical impulses
-Epithelial tissue, covers body surfaces (internal and external)
-Muscle tissue, contracts
-Connective tissue, hold other tissue together or act as transport mediums

Question 10

Organ systems

Answer 10

• Large multicellular organisms have coordinated organ systems
• Composes of a number of organs working together to carry out major functions

Question 11

Gaseous exchange system

Answer 11

Extracts oxygen for respiration from air, expels carbon dioxide

Question 12

Cardiovascular systems

Answer 12

• Moves blood around body

- Effective transport system

Question 13

Digestive system

Answer 13

Take in food, break down large insoluble molecules into small soluble ones

Absorbs nutrient into blood, retains water, removes undigested material

Question 14

Squamous Epithelium

Answer 14

• Made up of specialised squamous epithelium cells, known as pavement epithelium due to flat appearance
• Very thin due to squat or flat cells that make it up, one cell thick
• Present when rapid diffusion essential, forms lining of lungs

Question 15

Ciliated epithelium

Answer 15

• Cilia epithelial cells
• Hair like structure called cilia, move in rythmic manner (lines the trachea)
• Goblet cells, release mucus, trapping unwanted praticles

Question 16

Cartilage

Answer 16

• Connective tissue found in ear, nose, between bones
• Contains fibres of elastin and collagen
• Firm, flexible connective tissue compound of chondryate cells embedded into extracellular matrix

Question 17

Muscle

Answer 17

• Contract in order to move body
• Different types of fibres: (skeletal muscles, connect to bones)
• Contain myofibrils which contain contractive proteins

Question 18

Number of different plant cell tissues

Answer 18

Epidermis tissue (covers plant surfaces)

Vascular tissue (transport water and nutrients)

Question 19

Epidermis

Answer 19

Single layer closely packed cells covering surface

Usually covered by waxy, waterproof cuticle to reduce water loss

Question 20

Xylem tissue

Answer 20

Vascular tissue responsible for transport of water and mineral

Composed of vessel elements, elongated dead cells

Walls strengthened with lignin, provides support

Question 21

Phloem Tissue

Answer 21

Vascular tissue responsible for transport of organic nutrients (particularly sucrose)

Composed of columns of sieve tube cells separated by performed walls called sieve plates

Question 22

Inside the cell (stages)

Answer 22

Cell, nucleus, chromosomes, DNA, section of DNA is a gene

Question 23

Diploid mother cell (meaning)

Answer 23

Has a full set of DNA
(In process of cell division the diploid mother cell will replicate the whole set of DNA. One full set in each diploid daughter cell).

Question 24

What is the function of the spindle fibres

Answer 24

The pull the chromosome to opposite poles

Question 25

Why must the DNA be replicated in mitosis

Answer 25

Because it’s necessary when all daughter cells have to be identical. This is the case during growth, replacement and repairs of tissues.

Question 26

Cell cycle

Answer 26

• Gap phase 1 (cell groups and new organelles and proteins are made)
• G1 checkpoint (The cell checks chemicals needed replication present and for any damage to DNA before entering S-phase)
• Synthesis (cell replicates DNA ready to divide by mitosis)
• Gap phase 2 (cell keeps growing and proteins needed for cell division are made)
• G2 Checkpoint (cell checks if all DNA ha s been replicated without damage)
• M Phase (mitosis and cytokinesis)
• Metaphase checkpoint

Question 27

Cancer

Answer 27

A group of many different diseases caused by uncontrolled division of cells.

Question 28

Tumours

Types

Answer 28

An abnormal mess of cells
Benign (stops growing and don’t travel to other regions of body)
Malignant (continues to grow unchecked and uncontrolled, the basis of cancer)

Question 29

What are tumours often a result of?

Answer 29

Damage or spontaneous mutation of the genes that encode the proteins that are involved in regulating the cell cycle, including the checkpoint proteins.

Question 30

Interphase

Answer 30

Cell carries out normal functions, but also preps to divide.
Cells DNA unravelled and replicated (and its organelles).
ATP content increased

Question 31

Meiosis ll (second division)

Answer 31

-The 2 daughter cells undergo Prophase ll, Metaphase ll, Anaphase ll, Telophase ll and cytokinesis.

• In anaphase ll the pairs of sister chromatids are separated, each new daughter cell inherits one chromatid from each chromosome
• 4 genetically different haploid cells (gametes)

Question 32

Prophase

Answer 32

Chromosomes condense (shorter and fatter).
Tiny bundles (centrioles) start moving opposite ends, forming network of protein fibres (the spindles).
Nucleus envelope  breaks down and chromosomes lie free, cytoplasm

Question 33

Metaphase

Answer 33

The chromosomes (each with 2 chromatids) line up along middle at the spindle equator, become attached to the spindle by their centromere.
At metaphase checkpoint (cell checks all chromosomes are attached to spindle fibres before mitosis can continue).

Question 34

Anaphase

Answer 34

Centromeres divide, separating each pair of sister chromatids
Spindles contract pulling chromatids to opposite ends of the cell, centromere first.

Question 35

Telophase

Answer 35

Chromatids reach opposite poles on the spindle fibres
Uncoil and become long again (now called chromosomes)
Nuclear envelope forms around each pair of chromosomes (now 2 nuclei)

Question 36

Cytokinesis

Answer 36

Cytoplasm divides (get two identical daughter cells, genetically identical to original cell and each other)
Cytokinesis usually begins at Anaphase, ends Telophase (a separate process to mitosis)