Multicellular Organisms

Question 1

What does it mean for cells to specialize?

Answer 1

Specific cell types have a different structure to permit them to perform a specific function, this is called cell specialization. For example: the sperm cell has a flagellum. This is to help them travel to the ovum.

Question 2

What is DNA?

Answer 2

DNA is a very long molecule that carries genetic information. the DNA in the nucleus consists of long, loosely packed strands called chromatin.

Question 3

What are genes?

Answer 3

A gene is a small section of DNA on a chromosome, that code for a particular sequence of amino acids, to make a specific protein. It is the unit of heredity, and may be copied and passed on to the next generation

Question 4

What is protein synthesis?

Answer 4

The cytoplasm contains a large collection of chemicals called amino acids. The coding DNA carries genetic information that cells or multicellular organisms use to produce a sequence of amino acids called a polypeptide. A polypeptide, or several polypeptide chains, fold to form a molecule called a protein. The production of a protein by cells using genetic information encoded in a specific gene.

Question 5

What are the 5 steps of protein synthesis?

Answer 5

1. Unwinding the DNA double helix exposes the gene
2. RNA polymerase binds to the DNA (complementary base pairs)
3. RNA polymerase makes the messenger RNA molecule (transcription)
4. mRNA is transported out of the nucleus to ribosomes in cytoplasm
5. Ribosomes attach to mRNA to assemble amino acids in codons (groups of 3) into a specific polypeptide (translation)

Question 6

How do cells differentiate and express?

Answer 6

Cells in a multicellular organism develop differently to become specialized. All of the cells are genetically identical, or have the same genome. Different types of cells form in multicellular organisms because their cells use some genes to produce specific proteins, but not others. This is called gene expression.

Question 7

What are the levels of organization within a multicellular organism?

Answer 7

Cell > Tissue > Organ > Organ System > Organism

Question 8

Examples of different animal tissues

Answer 8

Nerve – involved in transmitting information, made of neurons
Muscle – is responsible for movement, made up of muscle cells called fibres
Connective – connect other tissues and organs together, eg. blood, fat and bone cells
Epithelial – covers the external body surface, lines organs and cavities and acts as a protective barrier against pathogens etc.
Reproductive – responsible for the production of sex cells

Question 9

Examples of plant tissues

Answer 9

Dermal tissue – provides a protective cover
Vascular tissue – involved in transporting material
Ground tissue – store food energy, perform photosynthesis and provide structural support

Question 10

Plant organs and systems

Answer 10

root – physically anchors and support the plant, absorb water and minerals from the soil, store sugars produced during photosynthesis
stem – holds plant upright, consists of vascular tissue that transports water and sugar between roots and leaves
leaves – collect sunlight and make sugars by photosynthesis

Question 11

What is the cardiovascular system and its main organs?

Answer 11

The cardiovascular system consists of the heart, blood vessels, and blood. Its purpose is to transport nutrients, oxygen, and hormones to cells throughout the body and remove metabolic wastes. Protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defend the body against foreign microbes and toxins. Clotting mechanisms are also present that protect the body from blood loss after injuries.

Question 12

What is the circulatory system and its main organs?

Answer 12

The circulatory system consists of the heart, lungs, blood, arteries, capillaries and veins. The circulatory system carries blood and dissolved substances to and from different places in the body. The heart has the job of pumping these things around the body. The heart pumps blood and substances around the body in tubes called blood vessels.

Question 13

What is the digestive system and its main organs?

Answer 13

The digestive system consists of the mouth, oesophagus, stomach, small intestine, large intestine, liver, gallbladder, and pancreas. The purpose of the digestive system is to take in food, break it down into a useful form your cells can use (nutrients), and get those nutrients into your blood so that the circulatory system can take it to every cell in your body.

Question 14

What is the endocrine system and its main organs?

Answer 14

The endocrine system consists of the thyroid, parathyroid, pancreas, ovary and the hypothalamus.
The endocrine system is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs. These hormones regulate the body’s growth, metabolism, and sexual development and function.

Question 15

What is the integumentary system and its main organs?

Answer 15

The integumentary system consists of the epidermis, dermis, hypodermis, associated glands, hair, and nails.
The integumentary system is the set of organs forming the outermost layer of an animal’s body. It comprises the skin and its appendages, acting as a physical barrier between the external environment and the internal environment that it serves to protect and maintain.

Question 16

What is the lymphatic system and its main organs?

Answer 16

The lymphatic system consists of bone marrow, spleen, thymus gland, lymph nodes, and tonsils. The lymphatic system is our body’s ‘sewerage system’. It maintains fluid levels in our body tissues by removing all fluids that leak out of our blood vessels. The lymphatic system is important for the optimal functioning of our general and specific immune responses.

Question 17

What is the muscular system and its main organs?

Answer 17

The skeletal system consists of the skeletal, smooth and cardiac muscles. The muscular system is composed of specialized cells called muscle fibres. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement.

Question 18

What is the nervous system and its main organs?

Answer 18

The nervous system consists of the brain, spinal cord, and sensory organs. The nervous system is the major controlling, regulatory, and communicating system in the body. It is the centre of all mental activity including thought, learning, and memory. It is in control of body’s internal environment to maintain ‘homeostasis’ (an example beings: keeping the body at an appropriate temperature)

Question 19

What is the respiratory system and its main organs?

Answer 19

The respiratory system consists of the oral cavity, nasal cavity, pharynx, larynx, trachea, diaphragm, lungs, bronchi, alveoli and ribcage. Your respiratory system is the network of organs and tissues that help you breathe. This system helps your body absorb oxygen from the air so your organs can work. It also cleans waste gases, such as carbon dioxide, from your blood.

Question 20

What is the skeletal system and its main organs?

Answer 20

The skeletal system consists of muscles, cartilage, tendons, ligaments, joints and connective tissue.
The skeletal system works as a support structure for your body. It gives the body its shape, allows movements, makes blood cells and provides protection for organs and stores minerals.

Question 21

What is the urinary system and its main organs?

Answer 21

The urinary system consists of kidneys, renal pelvis, ureters, bladder and urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.

Question 22

What is the exchange of materials with the environments?

Answer 22

Diffusion is the main way in which substances move over short distances in organisms. The substances are transported in the bloodstream, from where they can diffuse in and out of cells.

Question 23

What is an example of gas exchange?

Answer 23

Breathing involves the exchange of gases in the lungs; a process that occurs by diffusion. Oxygen in inhaled air diffuses through the lungs and into the bloodstream. The oxygen is then transported throughout the body. Carbon dioxide is the waste gas produced by respiration. Carbon dioxide diffuses from body tissues into the bloodstream and is exhaled via the lungs. Alveoli are the tiny air sacs at the end of the bronchioles, in which gas exchange occurs.

Question 24

What is photosynthesis?

Answer 24

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

Question 25

What are the main parts of a leaf cell?

Answer 25

The waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, vascular bundle (xylem, phloem), lower epidermis, chloroplast

Question 26

What is a waxy cuticle?

Answer 26

This is usually thickest on the upper epidermis, but is also present on the lower epidermis. The waxy cuticle is transparent, so light passes through. Its function is to reduce water loss from the leave

Question 27

What is the upper epidermis?

Answer 27

The upper epidermis is a thin layer of cells. It does not contain chloroplasts, and allows light to pass to the mesophyll cells.

Question 28

What is the palisade mesophyll?

Answer 28

This is a tightly packed layer of cells containing many chloroplasts. Their function is to capture light for photosynthesis.

Question 29

What is the spongy mesophyll?

Answer 29

This layer contains chloroplasts to capture light that has not been absorbed by the palisade mesophyll, but also has an important role in gas exchange. The spongy mesophyll has large air spaces between the cells, hence the description ‘spongy’. This allows for the diffusion of gases between the cells and the air spaces.

Question 30

What are the vascular bundles?

Answer 30

Vascular bundles (veins) made up of xylem which carries water to the leaf, and phloem which transports foods from the leaf.

Question 31

What is the lower epidermis?

Answer 31

This layer is also transparent, containing no chloroplasts, except in the specialized guard cells, which open and close the stomata. The lower epidermis produces the waxy cuticle.

Question 32

What is a chloroplast?

Answer 32

Chloroplasts are a specialized organelle in plant cells, their main role is to carry out the process of photosynthesis. Chloroplasts are green-coloured because of the presence of a photosynthetic pigment called chlorophyll which captures energy from sunlight. The light energy captured by chlorophyll is needed to carry out the reactions of photosynthesis and produce glucose

Question 33

What is aerobic respiration?

Answer 33

Aerobic respiration is a chemical reaction that transfers energy to cells. The waste products of aerobic respiration are carbon dioxide and water.

Question 34

What it gas exchange in leaves?

Answer 34

Plants need to ‘breathe’ carbon dioxide from the atmosphere in order to photosynthesize, or change sunlight into usable chemical energy. They also need to release oxygen back into the atmosphere as a waste product of cellular processes. This gas exchange occurs through the stomata. While this happens, some water is lost from the plant. Guard cells are a pair of cells that surround each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Guard cells tend to open stomata during the day when there is lots of sunlight, and close stomata at night when the sun is not present and photosynthesis is not occurring. They will also close stomata if the air is dry or hot, which minimizes water loss through evaporation.

Question 35

Chemical Digestion Vs Mechanical

Answer 35

Mechanical Digestion – Involves the tearing, crushing and mashing of food. Example: When you take a bite and chew it with your teeth or when your stomach muscles contract and relax.
Chemical Digestion – When chemicals called enzymes help break down food into nutrients.

Question 36

Ingestion, Digestion, Egestion

Answer 36

Ingestion is the intake of food. Digestion is the physical or chemical breakdown of food, so that it can be absorbed into the bloodstream. Egestion is the removal of indigestible waste materials from the body.

Question 37

Why is the digestive system specialized?

Answer 37

• A large surface area, with villi and microvilli.
• A transport system (capillaries and lacteals) to maintain the concentration gradient.
• A thin epithelial layer, providing a short distance for absorption.
• Specialized cells produce enzymes and mucus, to aid digestion.

Question 38

What is the Ileum?

Answer 38

The ileum is the final section of the small intestine. The function of the ileum is mainly to absorb vitamin B12, bile salts, and any products of digestion that were not absorbed by the jejunum.

Question 39

What are villi?

Answer 39

Villi increases the internal surface area of the intestinal walls making available a greater surface area for absorption.

Question 40

Identify macromolecules and enzymes that break them down and where

Answer 40

Macromolecule: Proteins
Digestive enzyme: Proteins
Monomer that’s produced: Amino acids

M: Carbohydrates
D: Amylases
Mo: Glucose

M:Lipids
D: Lipases
Mo: Fatty acids and glycerol

Question 41

What is an open and closed system?

Answer 41

Open circulatory systems are those found in animals that have blood that do not flow in blood vessels. Insects have open circulatory systems because they don’t have veins, capillaries, and arteries that carry their blood. Closed circulatory systems are those that are found in animals that have veins, capillaries, and arteries that carry their blood. Humans and other large and active animals have this system.

Question 42

What is in blood?

Answer 42

Red blood cells, white blood cells, oxygen, carbon dioxide, digested food, plasma, hormones, platelets and waste.

Question 43

Structure and function of arteries

Answer 43

Arteries carry blood away from the heart. Pulmonary arteries transport blood that has a low oxygen content from the right ventricle to the lungs. Systemic arteries transport oxygenated blood from the left ventricle to the body tissues.

Question 44

Structure and function of veins

Answer 44

Veins carry blood toward the heart. After blood passes through the capillaries, it enters the smallest veins, called venules. From the venules, it flows into progressively larger and larger veins until it reaches the heart.

Question 45

Structure and function of capillaries

Answer 45

Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins).

Question 46

Whats the flow of deoxygenated blood and oxygenated blood

Answer 46

the deoxygenated blood enters the body then travels through the superior vena cava, right atrium, the right ventricle through to the pulmonary arteries and into the lungs. During this time the blood becomes oxygenated. It then continues through the pulmonary veins into the left atrium then the left ventricle onto the aortic valve and back into the body.