Eukaryotic Cell Diversity

Question 0

What is a protist?

Answer 0

A large and diverse group of eukaryotic micro-organisms. Most are single celled but a small number are multi-cellular.

Question 1

What is the main difference between eukaryotes & prokaryotes?

Answer 1

The presence of organelles & DNA enclosed in a nucleus.

Question 2

Suggest a problem for single-celled organisms which are very large.

Answer 2

The absorption of sufficient nutrients & the excretion of wastes. This is due to the volume to surface area ratio.

Another problem is transport & communication between distant cell areas.

Question 3

List two ways in which large single-celled organisms can combat problems relating to their size regarding nutrients & waste.

Answer 3

Many Protists have evolved a flattened, lobed shape to increase surface area.

Many have also evolved the ability to engulf food, such as the amoeba.

Question 4

What is the process by which single-celled organisms engulf food called?

Answer 4

Endocytosis.

Question 5

Explain the process of endocytosis.

Answer 5

A flexible cell surface & the ability to extend lobes of cytoplasm known as pseudopods a.

Question 6

What strategy to large unicellular Protists have to address the problem of communication within the cell?

Answer 6

Extra large nuclei or more than one nucleus to reduce distance between the nucleus and other parts of the cell.

Question 7

Name an advantage of colony formation

Answer 7

Colonies are larger in size than individual organisms, which may reduce predation by filter feeders.

Question 8

What are chlorophyta?

Answer 8

Photosynthetic eukaryotes, some of which are unicellular, some colony-forming and others multicellular.

They are a division of the eukaryotic green algae.

Question 9

What is the difference between colonies and multicellular organisms?

Answer 9

Colonies contain identical individuals.

Question 10

What is volvox? Does it count as a colony or a multicellular organism?

Answer 10

It is a very simple multicellular organism because it contains differentiated cells. Several thousand cells can be present, some of which are somatic. Others are reproductive & can lead to the formation of a new colony.

Question 11

List some of the features of fungi.

Answer 11

The majority of fungi consist of microscopic filaments called hyphae, which grow at their tips and branch repeatedly.

A mass of hyphae is called mycelium.

Hyphae have rigid cell walls.

Question 12

Are fungi multicellular or unicellular? Why are they difficult to classify?

Answer 12

They are generally considered to be multicellular. It is difficult to classify them because they can be made up of divisions in the hyphae to make cell-like compartments, or have no divisions and multiple nuclei in each hypha.

Question 13

Are there single-celled fungi?

Answer 13

Yes, many spend part or all of their life cycle in single-celled or yeast form.

Question 14

What are the three main tissue types in flowering plants?

Answer 14

Ground tissue, vascular tissue & dermal tissue.

Question 15

Define plant.

Answer 15

Multicellular eukaryotes which photosynthesise, they evolved from green algae. They are non motile with rigid cell walls.

Question 16

Describe plant ground tissue.

Answer 16

It provides packing and support and energy storage.

Question 17

What is a palisade cell and where is it found?

Answer 17

Photosynthetic cells found in the ground tissue of plants.

Question 18

What are parenchyma cells?

Answer 18

The basic structural element of plants which form the majority of stems, roots & leaves.

Question 19

What is a plasmodesmata?

Answer 19

Small pores linking the cells of plants. They are lined by a plasma membrane and have a strand of cytoplasm in the middle.

Question 20

Name & briefly describe the two types of vascular tissue in plants.

Answer 20

Xylem: transports water and dissolved ions from the roots around the rest of the plant.

Phloem: transports the produce of photosynthesis around the plant.

Question 21

What is plant dermal tissue?

Answer 21

Epidermis of a plant, it covers the entire plant. It is usually a single cell thick.

In shoots it has a cuticle.

Question 22

What are stomata?

Answer 22

Pores in the epidermis of leaves. They open & close to facilitate the gas exchange needed for photosynthesis.

Question 23

List the principle types of animal cells.

Answer 23

Epithelial cells
Endocrine cells
Muscle cells
Neurones
Connective tissue
Adipocytes
Blood cells
Immune system cells
Germ cells

Question 24

Give examples of epithelial cells.

Answer 24

Epidermis (outer layer of skin)
Lining of intestine, blood vessels and lungs.
Cells of glands (such as salivary or mammary)

Question 25

What is the function of epithelial cells?

Answer 25

Protection, barrier, absorption, secretion.

They form sheets of closely linked, polarised cells.

Question 26

What are endocrine cells? Give examples.

Answer 26

Hormone-producing cells which produce and secrete chemical messengers into circulation. They are found in the pancreas and adrenal gland.

Question 27

What are the three types of muscle cell and how do they differ?

Answer 27

Smooth muscle: found in internal organs such as the intestine & blood vessels. Controls involuntary movement such as peristalsis.

Skeletal muscle: movement of limbs.

Cardiac: contractions of the heart.

All contain contractile proteins.

Question 28

Outline the features of neurones.

Answer 28

Found in the brain, spinal cord & ganglia within the body. They allow rapid and specific communication.

Polarised cells with long processes, special membrane properties allow electrical signalling.

Question 29

List the different types of animal support cells.

Answer 29

Osteoblasts & osteoclasts (bone cells)
Cartilage
Fibroblasts.

Question 30

What is the role of fibroblasts?

Answer 30

They produce much of the extra cellular material.

Question 31

What are adipocytes?

Answer 31

Energy storage & protective cells with cytoplasm composed mainly of lipids. They are found under the skin and around certain organs.

Fat tissue.

Question 32

List two notable features of mammalian red blood cells.

Answer 32

They contain haemoglobin which binds to oxygen.

They loose their nucleus when mature.

Question 33

What are leukocytes?

Answer 33

Immune system cells for defence.

Question 34

Name the two main types of leukocytes and the way in which they function.

Answer 34

B lymphocytes & plasma cells: produce antibodies

Macrophages: ingest pathogens

Question 35

What are germ cells & in what way are they different?

Answer 35

Reproductive cells (eggs and sperm). They contain half the normal number of chromosomes.

Question 36

How do the absorptive properties of epithelial cells arise?

Answer 36

Because of the presence and arrangement of specific proteins called transporters. Transporters associated with the absorption of nutrients are located in the part of the cell membrane which comes into contact with food. The apical surface.

Question 37

Give an example of a polarised cell.

Answer 37

Epithelial cells are different one side of the cell to the other. Absorption is facilitated by micro villi.

Question 38

What is the name used for the units of DNA that encode different proteins?

Answer 38

Genes.

Question 39

Give two examples of cellular interactions that occur in the gut.

Answer 39

1) coordinated smooth muscle contraction involves interactions between individual smooth muscle cells.
2) smooth muscle cells are stimulated to contract or relax by the actions of the neurones.