Bio (Overall)

Question 1

Define Growth

Answer 1

An irreversible increase in size (mass) as a result of an increase in the number of cells in an organism

Question 2

Define Development

Answer 2

Development is defined as an increase in complexity as cells differentiate into tissues and begin to carry out specific functions.

Question 3

List and describe briefly the 3 stages of growth

Answer 3

1. Cell division - This is the increase in the number of cells as mitosis occurs
2. Cell enlargement - Increase in the size of the cells after mitosis
3. Cell differentiation - specialization of cells as they develop into tissues and assume special roles. This can be considered as development

Question 4

Why are growth and development important to an organism

Answer 4

Growth and development are important for an organism to become a more mature individual, capable of reproducing. On the fusion of gametes, an organism is merely a cell. The cell then divides and development occurs to form all the tissues and organs of the organism . Growth and development continue as the individual matures and becomes more capable of reproducing new organisms

Question 5

What are apical meristems? (plants)

Answer 5

The growing regions on a seedling as it grows into a plant from a seedling, they are found at the tips of roots and shoots

Question 6

List the 5 main hormone groups found in plants. briefly describe their functions

Answer 6

1. Auxins - These are produced by cells in the tip of the shoot. they promote primary growth by increasing rate of cell elongation of cells immediately behind the tip of the shoot; e.g indole acetic acid
2. gibberellins - stimulate growth of shoots and leaves;
3. cytokinins - stimulate cell division;
4. abscisic acid - a powerful growth inhibitor, often acting antagonistically to growth promoteres
5. ethene (ethylene) - promotes fruit ripening, particularly in bananas, melons and tomatoes.

Question 7

List 3 simple investigations designed to demonstrate growth in plants

Answer 7

• measuring changes in height or growth of the plant as it is growing
• measuring changes in mass of the entire plant;
• measuring the surface area of the leaves or roots
• counting the number of leaves.

Question 8

List atleast 2 differences between the endocrine and exocrine glands

Answer 8

1. Difference in the means of transport and secretion: In Endocrine glands blood transports the secretion from the gland to the target organ and in the exocrine glands a duct transports the secretion from the gland to its target organ
2. Different types of secretion: Endocrine glands secret hormones like insulin whereas exocrine glands secrete substances like saliva or pancreatic juices

Question 9

What are hormones

Answer 9

Hormones are chemicals that cause a change in some cells of the body called target cells. This change results in a specific response

Question 10

List 4 examples of hormones in humans and briefly explain their purpose

Answer 10

Thyroxin: thyroxin is responsible for the regulation of basal metabolic rate and regulation of growth and development

Insulin: Helps to regulate blood glucose.

adrenalin: This hormone is responsible for the ‘fight or flight ‘ resposnse when someone is in stressful situations
oestregen: Responsible for the promotion and development of secondary female characteristics
testosterone: responsible for the development of secondary sexual characteristics

Question 11

Define the term ‘gland’

Answer 11

A gland is a structure which secretes a specific substance

Question 12

What are the functions of the following hormones: pituitarary growth hormone, Antidiuretic hormone (ADH) and thyroid stimulating hormone

Answer 12

The pituitary growth hormone stimulates growth of the entire body: too much causes gigantism;too little causes dwarfism

The antidiuretic hormone (ADH) stimulates the kidneys to reabsorb more water from filtrate when the blood becomes too concentrated

thyroid stimulating hormone stimulates the thyroids into activity

Question 13

Define Metabolism

Answer 13

Metabolism is the term used to describe all chemical reactions going on in the body

Question 14

List and explain 2 disorders that occur in the thyroid gland

Answer 14

Goitre - Goitre occurs due to overactivity of the thyroid gland (hyperthyroidism). Goitre is a swollen thyroid gland. Hyperthyroidism include symptoms such as restlessness, irritability and loss of body mass

Cretinism - Cretinism is a condition found in children that results in retarded physical, mental and sexual development. results from underactivity of the thyroid gland (hypothyroidism) which can be cause by a deficiency of iodine in the diet

Question 15

What are secondary sexual characteristics?

Answer 15

Secondary sex charactersitics are physical characteristics that seperate that seperate the male sex from the female sex. The development of these characteristics prepares the organism for reproduction

Question 16

describe diabetes and list atleast 3 symptoms

Answer 16

Diabetes is a deficiency in insulin production which causes there to be no control of blood glucose level

Symptoms include

Hyperglycaemia or high blood glucose level;

glucose present in urine;

breakdown of muscle tissue

loss of weight

tiredness.

Question 17

The pancreas is both an endocrine and exocrine gland, where is it found?

Answer 17

It is found just below the stomach.

Question 18

State the purpose of the pancreas as a: 1.Endocrine gland

2. Exocrine gland

Answer 18

As an endocrine gland the pancreas secretes hormones into the blood such as insulin which helps to regulate blood glucose

As an exocrine gland it secretes enzymes into the duodenum via the pancreatic duct

Question 19

Where are the adrenal glands found in the body?

Answer 19

These glands are located just above the kidney and prepare the body for action. They secrete adrenalin, which is known as the ‘fight or flight’ hormone.

Question 20

What is the purpose of adrenalin and what are some effects that occur when it is secreted

Answer 20

1. The purpose of adrenalin is to prepare the body to handle dangerous life-threatening situation
2. The effects of adrenalin are:
   - pupils of the eyes dilate - Animal can ‘see’ better;
   - Increased mental awareness- Increases ability to respond to situation;
   - In the liver, glycogen is converted to glucose - more glucose is available for the muscles to work harder;
   - heartbeat rate increases - blood is taken more quickly to muscle cells;
   - digestion is inhibited - blood flow is directed from the gut area to more important areas like muscles

Question 21

List some differences between the Nervous system and the endocrine system

Answer 21

1. In the nervous system messages travel as electical impulses along nerves while in the endocrine system messages travel as chemicals in the blood
2. In the nervous system messages travel rapidly whereas in the endocrine system messages travel slowly
3. In the nervous system messages are carried to specific regions of the body, In the endocrine system messages are transported to all parts of the body but only produce a reaction in target cells
4. In the nervous system messages have an immediate effect on the body but in the endocrine system messages have a slower effect on the body
5. In the nervous system effects are short lasting, on the other hand effects caused by the endocrine system may be long lasting

Question 22

What is Germination

Answer 22

Germination is the growth of a seed into a seedling

Question 23

List and briefly describe the 3 conditions required for germination

Answer 23

1. water - it moves rapidly into the micropyle and to all the cells. Enzymes are activated and starch is broken down to glucose so that it can be used in respiration
2. oxygen - it is needed for respiration
3. warmth, or a suitable temperature which is the optimum temperature for the enzymes

Question 24

Draw (or sketch) and label diagram of a seed

Answer 24

View seed diagram for answer

Question 25

Explain the purpose of each: testa, cotyledon, micropyle, radicle and plumule

Answer 25

Testa - The testa is a protective seed coat, it’s purpose is to protect the embryo

Cotyledon - The cotyledon is the storage of food within the seed

Micropyle - the micropyle’s purpose is to absorb water and help in the germination of the seed

radicle - the radicle is a part of the embryo and it grows into the root as the seed develops

plumule - the plumule is a part of the embryo and it grows into the shoot as the seed develops

Question 26

Define the terms ‘autotroph’ and ‘heterotroph’

Answer 26

An autotrph is an organism thay is able to make it’s own food (organic substances) from simple substances (inorganic substances). A plant is an autotroph - When it photosynthesises it makes glucose from carbon dioxide

A heterotroph is an organism that takes in organic food when it feeds. It must have a supply of organic food sicne it cannot manufacture it for itself

Question 27

Describe the difference between epigeal germination and hypogeal germination

Answer 27

Epigeal germination is seen when cotyledons rise out of the soil as the seedling grows. Hypogeal germination is seen when the cotyledons stay underground during germination

Question 28

What is photosynthesis?

Answer 28

Photosynthesis is the process by which a plant makes it’s own food

Question 29

Explain the Light-dependent state of photosynthesis

Answer 29

Chloroplasts are organelles seen in green plant cells. they contain the green pigment chlorophyll which ‘traps’ the light energy from the Sun. The energy is used to split water (H2O) into hydrogen (H) and oxygen (O) The oxygen is a waste product and diffuses out of the leaf.

Question 30

Explain the Light-independent stage

Answer 30

The hydrogen comnbines with carbon dioxide (CO2) to make glucose (C6H12O6) This stage of photosynthesis does not need light and can happen during the dark

Question 31

List atleast 3 ways in which the leaves of a plant are adapted to carry out photosynthesis

Answer 31

• They are generally broad and flat with a large surface area to absorb a lot of light and carbon dioxide.
• They lie at 90 degrees to the sunlight and are spaced around the stem to catch as much light as possible.
• Stomata (small holes) are present in the lower epidermis to allow gases to get in and out easily
• Chloroplasts are most numerous in the cells in the palisade layer which is in the top part of the leaf, closest to the sunlight.

Question 32

Explain the functions of guard cells during photosynthesis

Answer 32

Their function is to regulate the size of the opening of the stomatal pore. They vary the size of the opening of the stoma by changing their shape,

Question 33

Explain how the stomatal opening varies as a result of changes in the turgidity of the guard cells

Answer 33

• when they are turgid the stoma opens;

- when they are flaccid, the stoma closes.

Question 34

What are some observations that can be made about the stomata of the plant

Answer 34

Most stomata open during thr day and close at night

stomata generally close when a plant sufferes water stress, or when transpiration rate exceeds the rate of water absorption by the roots;

the stomata of some desert plants close during the day and open at night.

Question 35

Describe how carbon dioxide gas in the atmosphere gets to a photosynthesising cell inside a leaf

Answer 35

Carbon dioxide is in the atmosphere around the leaf and gets to the photosynthesizing cell by diffusion (it diffuses through the stomata). A photosynthesising cell uses carbon dioxide, and so the carbon dioxide diffuses into the cell from the surrounding air space where its concentration is greater.

Question 36

Describe how water gets to the chloroplast

Answer 36

Water moves by osmosis from the spil into the roots of the plant. It then travels up the xylem vessels in the stem and into the leaves. From the xylem in the leaf, water moves by osmosis to the palisade cells where it is used during photosynthesis.

Question 37

Define Nutrition

Answer 37

Nutrition is the process by which living organisms obtain or create food