8. Specialised Plant And Animal Tissues

Question 1

What are tissues?

Answer 1

A group of cells that work together to perform a specific function

Question 2

What are the 4 main tissue types in the body?

Answer 2

Epithelial (lining tissue)
Connective tissue
Muscle tissue
Nervous tissue

Question 3

What is epidermal tissue?

Answer 3

It is present in plants.
It consists of flattened cells that lack chloroplasts and form a protective covering over leaves, stems and roots.
Some are impregnated with a waxy substance which reduces water loss.

Question 4

What is vascular tissue?

Answer 4

It is concerned with transport
There are 2 types xylem and phloem
Both are present in vascular bundles

Question 5

What is the function of xylem?

Answer 5

To carry water and minerals from the roots to all parts of the plant

Question 6

What is the function of phloem?

Answer 6

Sieve tubes transfer the products of photosynthesis, in solution, from the leaves to parts of the plant that do not photosynthesise, such as roots, flowers and growing shoots.

Question 7

What are meristematic tissue?

Answer 7

Made up of meristems, the stem cells of plants.

All other plant tissue derives from meristematic tissue

Question 8

What are cambium cells?

Answer 8

A tissue layer that provides partially undifferentiated cells for plant growth
It is found in the area between xylem and phloem.

Question 9

What happens when cambium cells differentiate into xylem vessels?

Answer 9

Lignin is deposited in their cell walls to reinforce and waterproof them, but it also kills the cell.
The ends of the cell break down.
This forms continuous columns with wide lumens.

Question 10

What happens when cambium cells differentiate into phloem vessels?

Answer 10

Sieve plates develop between each cell
Companion cells retain their organelles and continue metabolic functions to provide ATP for active loading of sugars into the sieve tubes.

Question 11

What is the main function of leaves?

Answer 11

Photosynthesis

Question 12

What is the main function of roots?

Answer 12

Anchorage in soil
Absorption of mineral ions and water
Storage

Question 13

What is the main function of the stem?

Answer 13

Support
Holds leaves up so they are exposed to more sunlight
Transport of water and minerals
Storage of products of photosynthesis

Question 14

What is the main function of the flower?

Answer 14

Reproduction

Question 15

What is an organ?

Answer 15

A collection of tissues working together to perform the same function

Question 16

What are stem cells?

Answer 16

Undifferentiated cells capable of becoming any type of cell in the organism.
They’re described as pluripotent.
They can divide by mitosis for growth and tissue repair.

Question 17

What are the potential uses of stem cells?

Answer 17

Bone marrow transplants to treat diseases of the blood, immune system and some types of cancer.
New drugs can be tested on stem cell tissue before animal tissue.
Scientists can research what goes wrong when they’re diseased.
Repair of damaged tissue or replacement of lost tissue.

Question 18

What are erythrocytes?

Answer 18

Red blood cells that carry oxygen from the lungs to respiring cells.

Question 19

What are neutrophils?

Answer 19

A type of white blood cell that is phagocytic.

They can ingest invading pathogens.

Question 20

How are erythrocytes adapted to carry out their function?

Answer 20

They are small so have a large SA:V ratio, increased by the biconcave shape, this means that oxygen can diffuse across their membrane into the cell.
They are flexible so can change shape so that they can travel through narrow capillaries.
Most organelles are lost at differentiation which provides more space for haemoglobin molecules.

Question 21

How are spermatozoa specialised?

Answer 21

Many mitochondria carry out aerobic respiration to provide energy for the undulipodium to move and propel the cell towards to ovum.
They are small and thin so can move easily
Enzymes released from the acrosome digest the outer protective covering of the ovum
The head of the sperm contains the haploid male gamete nucleus.

Question 22

What are epithelial cells?

Answer 22

Cells that constitute lining tissue on the inside and outside of the body.

Question 23

How are epithelial cells adapted?

Answer 23

Squamous epithelial cell are flattened in shape
Many of the cells in the epithelium have cilia
This allows them to waft substances along the surface of the tissue.

Question 24

What are palisade cells?

Answer 24

Closely packed photosynthetic cells within leaves.

Question 25

How are palisade cells adapted?

Answer 25

Small air spaces between them allow CO2 to diffuse into the cells
Their large vacuole pouches chloroplasts to the edge of the cell, reducing the diffusion distance for CO2
They contain many chloroplasts to carry out photosynthesis
Cytoskeleton threads move chloroplasts towards and away from the leaf surface as light intensity changes.

Question 26

What are guard cells?

Answer 26

Cells that surround stomata in the leaf epidermis.

Question 27

How are guard cells adapted?

Answer 27

They control gas exchange and water loss within the leaf.
In bright light the guard cells take in water by osmosis and become turgid.
In low light the guard cells lose water and become flaccid, causing the stomata to close.
This controls the rate of transpiration and therefore limits the levels of water loss from the leaf, stopping the plant from wilting.

Question 28

What are root hair cells?

Answer 28

Epidermal cells on the outer layer of young plant roots.

Question 29

How are root hair cells adapted?

Answer 29

Their hair like projections increases their surface area for absorption of water and mineral ions from the soil.
Mineral ions are actively transported into the root hair cells, lowering their water potential and causing water to follow by osmosis
The root cells have special carrier proteins in the plasma membrane in order to actively transport the mineral ions in, using ATP produced in the cell.