Sexual Reproduction in Humans Revision Structured Question

1. (a) Where are sperms produced in mammals?

(b)(i) In what part of the body does fertilisation occur in a mammal.

(ii) Give the name of a vertebrate with external fertilisation.

(c) In what way are the nuclei of gametes different from the nuclei of other body cells?

(d) What is the fertilised ovum called?

(e) What type of nuclear division occurs when the fertilised ovum begins to divide into many cells?

(f) In what organ does the developing mammalian embryo grow?

(g) Write a short account of the nutrition of the mammalian embryo using the following terms: umbilical cords, placenta, capillary, amino acids.

2.  Figure 2.1 is a diagram of a developing mammalian fetus and part of the uterus wall.

4.1D Sec 2 Qn 4A.jpg

(a) On the diagram, label structure A, B and C.

(b) State the function of R.

(c)What type of tissue is found in S?

(d) Figure 2.2 shows a section through structure B taken at P-Q.

4.1D Sec 2 Qn 4B.jpg

(i) On the diagram label W and X.

(ii) With reference to structures W and X, state how they are involved in the nutrition, excretion and gas exchange of fetus.

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Answer:

1. (a) Testes of male

(b) (i) In the  oviduct of the female

(ii) Fish/frog

(c) The nuclei of gametes have only one set of chromosomes, while the other body cells have two sets.

(d) Zygote

(e) Mitosis

(f) Uterus

(g) Amino acids in the maternal blood spaces diffuse into the capillaries in the placenta. From these capillaries, the amino acids are carried to the embryo via the umbilical vein in the umbilical cord.

2. (a) A – Amnion

B – Umbilical cord

C – Placenta

(b) Acts as a shock absorber

(c) smooth muscle tissue

(d) (i) W – Umbilical artery

X – Umbilical vein

(ii) Nutrition: Dissolved food molecules e.g. glucose and amino acids are carried from the placenta to the fetus via X

Excretion: Waste products e.g. urea are carried from the fetus to the placenta via W.

Gas exchange: Oxygen is brought to the fetus from the placenta via X while carbon dioxide is carried away from the fetus to the placenta.

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Sexual Reproduction in Humans Revision MCQ Question

1. The diagram shows the reproductive organ of a human male.

Geylang mtd Q36.PNG

Which tube carries both sperms and urine?

2. The diagram shows parts of the male reproductive system.

ping yi q32.PNG

What will be the effect of removing gland X?
A.    To prevent the storage of sperm before fertilisation.
B.    To slow down the production of sperm.
C.    To stop the secretion of a male hormone.
D.    To release nutrients in the seminal fluid.

3. The level of oestrogen in the blood of a woman changes during a normal menstrual
cycle. Which graph shows these changes?

Pasir ris crest Q15.PNG

4. After sexual intercourse, sperms can survive for 3 days in the uterus and oviducts. Ovulation can occur any time from day 13 to day 15 and an ovum can live for 2 days after ovulation.

How long is the longest possible fertile phase of the menstrual cycle?
A.    2 days
B.    3 days
C.    5 days
D.   7 days

5. The graph below shows the changes in the level of oestrogen (represented by X) and
progesterone (represented by Y) in blood.

St gab Q34.PNG

With reference to the graph only, what are the approximate dates on which ovulation
occurred?
A.    Day 4 and 32
B.    Day 13 and 42
C.    Day 17 and 45
D.    Day 26 and 56

6. Which of the following is the correct order of events in human reproduction?
A.    fertilization –> ovulation –> implantation –> birth
B.    ovulation –> fertilization –> implantation –> birth
C.    ovulation –> implantation –> fertilization –> birth
D.   fertilization –> implantation –> ovulation –> birth

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Answer: BDBDBB

Asexual Reproduction Revision Structured Question

1. (a) Many plants increase their numbers by vegetative reproduction. How does Man make use of this process? Give a named example.

(b) Vegetative reproduction ensures that all of the offspring are genotypically identical. Explain briefly what this means.

2. Grafting is a technique used to increase the numbers of a particular variety of plant. The figure below shows how a stem cutting from a variety of commercially important fruit tree, A, may be grafted on to roots of a variety of no particular value, B.

O lvl 4.1A Sec 2 Q2.jpg

(a) State the type of reproduction shown by this process.

The new trees will eventually bear fruit.

(b) Explain which of the two varieties will be responsible for the characteristics of the fruit produced.

Variety:

Explanation:

(c) Describe the pathway followed by water from its absorption by the roots until it enters the stem cutting.

(d) Suggest three ways of ensuring the graft in the figure above will be successful.

1.

2.

3.

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Answer:

1(a) Stem cutting in sugar cane. This method of growing sugar cane is very rapid and the offsprings are identical to parent plant.

(b) Since there is no formation of fusion of gametes, no variation is introduced. Therefore offsprings are genetically identical.

2(a) Vegetative propagation

(b) A. Variety A bears flowers from which fruits develop. When pollen grains land on the stigma of the flowers of variety A, a fruit eventually forms when male gametes fuses with the female gamete in the ovule. Hence, variety A is responsible for the characteristics of the fruit.

(c) Water enters root hairs by osmosis. Once in root hair cell, it dilutes its cell sap so that water passes to the cortex cells. This process continues until water enters the xylem of variety B. From there, water moves up the stem cutting via the xylem by transpiration pull.

(d) 1. Stem cutting must be tied to the root stock

2. The junction should be protected by wax to prevent entry of microbes.

3. Stem cutting and root stock should be of similar diameter so both cambium can be in contact.

Asexual Reproduction Revision MCQ Question

1. Which statement is true of asexual reproduction in plants?

A.    Insects are needed to transfer pollen
B.    New plants grow from seeds
C.    Offsprings are genetically identical to their parents
D.    Two types of gamete are involved

2. Which of the following are genetically identical?

A.    Brothers and sisters in the same family
B.    Cuttings taken from the same plant
C.    Gametes from the same parent
D.    Seeds produced by the same tree

3. The offspring from asexual reproduction in plants are likely to

A.    be more resistant than their parent to disease
B.    develop into a new variety
C.    grow bigger than their parent
D.    have the same flower colour as their parent

4. A new plant may arise from a bud on the modified underground stem of a herbaceous perennial. This form of reproduction is called

A.    binary fission
B.    sexual reproduction
C.    vegetative propagation
D.    perennation

 

=========================================

Answer: CBCD

The Endocrine System (Effector) Revision Structured Questions

1. (a) The following diagram shows the blood glucose level in a person after ingesting a carbohydrate heavy meal.

St Pat P4 Sec B Q9.PNG

Using named examples, outline how the endocrine glands regulate blood glucose level from the first hour till the seventh hour.

(b) The response to changing blood glucose is a hormonal response while the response to bright and dim light is a nervous response. Compare and contrast the two different types of responses.

2.  Fig. 2.1 shows the changes in the blood glucose level of a healthy person and a person suffering from diabetes after eating a meal containing bread.

ping yi Q3 a.PNG

(a)(i)  Explain why there is a delay between eating the meal and the increase in the blood glucose concentration.

(ii)  Using the information in the graph, describe two differences between the response to eating the meal shown by the healthy person and the person with diabetes.

(iii)  Explain what causes the fall in the blood glucose concentration of the healthy person.

(b) Fig. 3.2 shows the relative change in the blood glucose concentration when a healthy person had nothing to eat for 24 hours.

ping yi Q3 b.PNGOn the graph in Fig. 3.2, sketch and label a line to show the relative change in the concentration of glucagon in the blood over the same period of time.

==================================================

Answer:

1. (a) After a heavy meal, there is an increase in blood glucose concentration. This triggers the islets of Langerhans to produce insulin. lnsulin is released by the endocrine glands into the bloodstream.

It results in various effects such as:
– lncreasing cell permeabilitg to glucose therefore increasing the uptake of glucose.
– lncreases the conversion of glucose to glycogen for storage in liver and muscle cells.
– lncreases the oxidation of qlucose in cells and tissue via the process of respiration.
Therefore resulting in a decrease in blood glucose concentration back to normal.

(b)

  • Nerves transmit signals by electrical impulses.
    Hormones transmit signals by chemical methods.
  • Electrical impulses are transmitted via nerves and straight to the brain.
    Hormones are excreted into the bloodstream by-passing the brain.
  • Nerve impulses can result in either voluntary or involuntary responses.
    Hormones always result involuntary responses.
  • Nerve impulses have long-lived responses.
    Hormones have long-lived and short-lived responses.
  • Nerve impulses result in very fast responses.
    Hormones result in slower responses.

2(a)(i)  Time taken for passage of food from mouth to reach intestine; Time taken for digestion (of starch in mouth); Time taken for absorption (of glucose in ileum)

(ii)  The increase in blood glucose concentration is faster / gradient of increase is steeper in the person with diabetes;
The increase in blood glucose concentration is greater in the person with diabetes;
The decrease in blood glucose eoncentration is slower in the person with diabetes

(iii) Insulin; released from pancreas/ lslets of Langerhans;
Excess glucose converted into glycogen

(b)  Line starts near 0 (accept less than 20), increases slowly; levels off about 14-16 hour; line decreases slowly after 14-16 hour

The Endocrine System (Effector) Revision MCQ Questions

1. In which of the following do hormones travel around the body?

A.    In glands
B.    In nerves
C.    In the blood plasma
D.    In the white blood cells

2. Which of the following results from increased secretion of adrenaline?

A.    Decreased breathing rate
B.    Decreased heart rate
C.    Decreased sweating
D.    Increased breakdown of glycogen

3. A small wild mammal was brought into the laboratory. Every time it was handled, the rate of its heartbeat increased considerably. This response was due to the secretion of a substance by

A.    adrenal gland
B.    pancrease
C.    testis
D.    thyroid

4. The diagram below shows how blood glucose levels are regulated in the human body.

geylang Q33 a.PNG

Which one of the following correctly identifies hormones X and Y?

Geylang Q33 b.PNG5. The person with diabetes mellitus is receiving treatment with insulin injections, The graph shows how this person’s blood glucose concentration changed during part of one
day. At what point was the insulin injection given?

Kuo chuan Q34.PNG

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Answer: CDACA

 

Homeostasis Revision Structured Questions

1.

1.11 P2 Q2.jpg

(a) Label the four structures indicated by the lines on the figure.

(b) Nate three structures shown in the figure that are concerned with temperature regulation and in each case indicate their function.

(c) Where in Man is the horny layer thickest?

2. Fig.2 shows the blood pressure in the main artery of the arm of a person before and immediately after having a hot bath.

1.11 P2 Q10.jpg

Fig. 2

(a) Using Fig. 2, calculate the rate of the person’s heartbeat before having the bath.

(b) While in the bath, the person’s body temperature rose from 36.7 to 38.5 degree Celcius. State two likely effects of the change in body temperature on the person’s face. Explain what causes each effect.

(c)(i) Suggest an explanation for the change in the person’s blood pressure immediately after having the bath.

(ii) What was the effect on the rate of heart beat of having the bath?

(d) Suggest two effects of prolonged exposure to temperatures below 0 degree Celcius.

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Answer:

1(a) Epidermis, sebaceous gland, sweat gland, dermis, epidermis (from the top left hand corner, clockwise direction)

(b) Capillary loops – Can dilate or constrict, regulating blood flow to the skin

Sweat gland – Produces sweat which on evaporation, helps to cool the body

Fat cell – Insulates against heat loss

(c) Palms of hands, soles of feet

2(a) No. of heartbeat in 6 seconds = 6

Hence, rate of heartbeat = 60/6 x 6 = 60 times per minute

(b) Effect 1 – Person’s face feels warm and looks flushed. As body temperature increases, arterioles in skin dilate so that more blood flows to the skin and heat in the blood is lost to the surrounding.

Effect 2 – Sweat forms on face. |Sweat glands are activated and produce sweat. As sweat evaporates, latent heat is removed and the body cools down.

(c)(i) As arterioles in skin dilate, pressure of blood flowing through decreases.

(ii) Increase the rate of heartbeat.

(d) 1. Shivering/Vasoconstriction

2. Body temperature may drop to as low as 35 degree Celcius

 

 

 

Homeostasis Revision MCQ Question

1. Which of the following structural features of the skin does not play a part in temperature regulation in a mammal?

A.    Hair erector muscles
B.    Fat in the dermis
C.    Malpighian layer
D.    Nerve endings

2. The graph shows changes in a person’s internal body temperature over a period of time.

1.11 Q23.jpg

During which period would the arterioles supplying blood to surface capillaries first become constricted?

3. Four processes that take place in the human body are listed.

1.    absorption of amino acids through the villi
2.    maintenance of constant body temperature
3.    production of lactic acid in muscles
4.    regulation of blood glucose concentration

Which two processes are directly controlled by negative feedback?

A.    1 and 3
B.    1 and 4
C.    2 and 3
D.    2 and 4

4. The graph below shows body temperature, plotted against external temperature, for two different organisms. Which one of the following could identify these organisms?

1.11 Q12.jpg

A.    1: Amphibian, 2: Fish
B.    1: Fish, 2: Mammal
C.    1: Insect, 2: Reptile
D.    1: Mammal, 2: Insect

5. By experiment, it was found that the heat loss per unit weight of a small mammal was greater than that of a large mammal, although their body temperature remained constant. Which one of the following conclusions can be draw from this result?

A.    Small mammals are more active than large mammals.
B.    Large mammals are better adapted than small mammals to their physical environment.
C.    Small mammals have a higher metabolic rate than large mammals.
D.    Large mammals have a greater surface area than small mammals.

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Answer: CDDDA

Learning Outcomes for O Level Biology SEAB 5158

Learning Outcomes as according to the 2018 O Level 5158 Biology (with SPA) Syllabus

 

CELL STRUCTURE AND ORGANISATION

Cell Structure & Organisation

  • identify cell structures (including organelles) of typical plant and animal cells from diagrams, photomicrographs and as seen under the light microscope using prepared slides and fresh material treated with an appropriate temporary staining technique:
    – chloroplasts
    – cell surface membrane
    – cell wall
    – cytoplasm
    – cell vacuoles (large, sap-filled in plant cells, small, temporary in animal cells)
    – nucleus
  • identify the following membrane systems and organelles from diagrams and electron micrographs:
    – endoplasmic reticulum
    – mitochondria
    – Golgi body
    – ribosomes
  • state the functions of the membrane systems and organelles identified above compare the structure of typical animal and plant cells state, in simple terms, the relationship between cell function and cell structure for the following:
    – absorption — root hair cells
    – conduction and support — xylem vessels
    – transport of oxygen — red blood cells
    differentiate cell, tissue, organ and organ system

 

MOVEMENT OF SUBSTANCES

Movement of Substances

  • define diffusion and describe its role in nutrient uptake and gaseous exchange in plants and
    humans
  • define osmosis and describe the effects of osmosis on plant and animal tissues
  • define active transport and discuss its importance as an energy-consuming process by which substances are transported against a concentration gradient, as in ion uptake by root hairs and uptake of glucose by cells in the villi

 

BIOLOGICAL MOLECULES

Biological Molecules

  •  state the roles of water in living organisms
  • list the chemical elements which make up
    – carbohydrates
    – fats
    – proteins
  • describe and carry out tests for
    – starch (iodine in potassium iodide solution)
    – reducing sugars (Benedict’s solution)
    – protein (biuret test)
    – fats (ethanol emulsion)
  • state that large molecules are synthesised from smaller basic units
    – glycogen from glucose
    – polypeptides and proteins from amino acids
    – lipids such as fats from glycerol and fatty acids
  • explain enzyme action in terms of the ‘lock and key’ hypothesis
  • explain the mode of action of enzymes in terms of an active site, enzyme-substrate complex, lowering of activation energy and enzyme specificity
  • investigate and explain the effects of temperature and pH on the rate of enzyme catalysed reactions

 

NUTRITION IN LIVING ORGANISMS

Nutrition in Plants

  • identify and label the cellular and tissue structure of a dicotyledonous leaf, as seen in transverse section using the light microscope and describe the significance of these features in terms of their functions, such as the
    – distribution of chloroplasts in photosynthesis
    – stomata and mesophyll cells in gaseous exchange
    – vascular bundles in transport
  • state the equation, in words and symbols, for photosynthesis
  • describe the intake of carbon dioxide and water by plants
  • state that chlorophyll traps light energy and converts it into chemical energy for the formation of carbohydrates and their subsequent uses
  • investigate and discuss the effects of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis (e.g. in submerged aquatic plant)
  • discuss light intensity, carbon dioxide concentration and temperature as limiting factors on the rate
    of photosynthesis

Nutrition in Humans

  • describe the functions of main regions of the alimentary canal and the associated organs: mouth, salivary glands, oesophagus, stomach, duodenum, pancreas, gall bladder, liver, ileum, colon, rectum, anus, in relation to ingestion, digestion, absorption, assimilation and egestion of food, as
    appropriate
  • describe peristalsis in terms of rhythmic wave-like contractions of the muscles to mix and propel the contents of the alimentary canal
  • describe the functions of enzymes (e.g. amylase, maltase, protease, lipase) in digestion, listing the substrates and end-products
  • describe the structure of a villus and its role, including the role of capillaries and lacteals in absorption
  • state the function of the hepatic portal vein as the transport of blood rich in absorbed nutrients from the small intestine to the liver
  • state the role of the liver in
    – carbohydrate metabolism
    – fat digestion
    – breakdown of red blood cells
    – metabolism of amino acids and the formation of urea
    – breakdown of alcohol
  • describe the effects of excessive consumption of alcohol: reduced self-control, depressant, effect on reaction times, damage to liver and social implications

 

TRANSPORT IN LIVING ORGANISMS

Transport in Flowering Plants

  •  identify the positions and explain the functions of xylem vessels, phloem (sieve tube elements and companion cells) in sections of a herbaceous dicotyledonous leaf and stem, using the light microscope
  • relate the structure and functions of root hairs to their surface area, and to water and ion uptake
  • explain the movement of water between plant cells, and between them and the environment in terms of water potential (calculations on water potential are not required)
  • outline the pathway by which water is transported from the roots to the leaves through the xylem vessels
  • define the term transpiration and explain that transpiration is a consequence of gas exchange in
    plants

Transport in Humans (Circulatory System)

  • identify the main blood vessels to and from the heart, lungs, liver and kidney
  • state the role of blood in transport and defence
    – red blood cells — haemoglobin and oxygen transport
    – plasma — transport of blood cells, ions, soluble food substances, hormones, carbon dioxide, urea, vitamins, plasma proteins
    – white blood cells — phagocytosis, antibody formation and tissue rejection
    – platelets — fibrinogen to fibrin, causing clotting
  • list the different ABO blood groups and all possible combinations for the donor and recipient in blood transfusions
  • relate the structure of arteries, veins and capillaries to their functions
  • describe the transfer of materials between capillaries and tissue fluid
  • describe the structure and function of the heart in terms of muscular contraction and the working of valves
  • outline the cardiac cycle in terms of what happens during systole and diastole (histology of the heart muscle, names of nerves and transmitter substances are not required)
  • describe coronary heart disease in terms of the occlusion of coronary arteries and list the possible causes, such as diet, stress and smoking, stating the possible preventative measures

 

RESPIRATION IN HUMANS

Respiration in Humans

  • identify on diagrams and name the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries
  • state the characteristics of, and describe the role of, the exchange surface of the alveoli in gas exchange
  • describe the removal of carbon dioxide from the lungs, including the role of the carbonic anhydrase enzyme
  • describe the role of cilia, diaphragm, ribs and intercostal muscles in breathing
  • describe the effect of tobacco smoke and its major toxic components — nicotine, tar and carbon monoxide, on health
  • define and state the equation, in words and symbols, for aerobic respiration in humans
  • define and state the equation, in words only, for anaerobic respiration in humans
  • describe the effect of lactic acid in muscles during exercise

 

EXCRETION IN HUMANS

Excretion in Humans

  • define excretion and explain the importance of removing nitrogenous and other compounds from the body
  • outline the function of the nephron with reference to ultra-filtration and selective reabsorption in the production of urine
  • outline the role of anti-diuretic hormone (ADH) in osmoregulation
  • outline the mechanism of dialysis in the case of kidney failure

 

HOMEOSTASIS

Homeostasis

  • define homeostasis as the maintenance of a constant internal environment
  • explain the basic principles of homeostasis in terms of stimulus resulting from a change in the internal environment, a corrective mechanism and negative feedback
  • identify on a diagram of the skin: hairs, sweat glands, temperature receptors, blood vessels and fatty tissue
  • describe the maintenance of a constant body temperature in humans in terms of insulation and the role of:
  • temperature receptors in the skin, sweating, shivering, blood vessels near the skin surface
  • co-ordinating role of the hypothalamus

 

COORDINATION AND RESPONSE IN HUMANS

The Nervous System

  • state the relationship between receptors, the central nervous system and the effectors
  • state that the nervous system — brain, spinal cord and nerves, serves to co-ordinate and regulate bodily functions
  • outline the functions of sensory neurones, relay neurones and motor neurones
  • discuss the function of the brain and spinal cord in producing a co-ordinated response as a result of a specific stimulus in a reflex action

Receptors – The eye

  • describe the structure of the eye as seen in front view and in horizontal section
  • state the principal functions of component parts of the eye in producing a focused image of near and distant objects on the retina
  • describe the pupil reflex in response to bright and dim light

Effectors – The endocrine system

  • define a hormone as a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver
  • explain what is meant by an endocrine gland, with reference to the islets of Langerhans in the pancreas
  • state the role of the hormone adrenaline in boosting blood glucose levels and give examples of situations in which this may occur
  • explain how the blood glucose concentration is regulated by insulin and glucagon as a homeostatic mechanism
  • describe the signs, such as an increased blood glucose level and glucose in urine, and the treatment of diabetes mellitus using insulin

 

CONTINUITY OF LIFE

Asexual reproduction

  • define asexual reproduction as the process resulting in the production of genetically identical offspring from one parent

Sexual reproduction in plants

  • define sexual reproduction as the process involving the fusion of nuclei to form a zygote and the production of genetically dissimilar offspring
  • identify and draw, using a hand lens if necessary, the sepals, petals, stamens and carpels of one, locally available, named, insect-pollinated, dicotyledonous flower, and examine the pollen grains using a microscope
  • state the functions of the sepals, petals, anthers and carpels
  • use a hand lens to identify and describe the stamens and stigmas of one, locally available, named, wind-pollinated flower, and examine the pollen grains using a microscope
  • outline the process of pollination and distinguish between self-pollination and cross-pollination
  • compare, using fresh specimens, an insect-pollinated and a wind-pollinated flower
  • describe the growth of the pollen tube and its entry into the ovule followed by fertilisation (production of endosperm and details of development are not required)

Sexual reproduction in humans

  • identify on diagrams, the female reproductive system and give the functions of: ovaries, oviducts, uterus, cervix and vagina
  • briefly describe the menstrual cycle with reference to the alternation of menstruation and ovulation, the natural variation in its length, and the fertile and infertile phases of the cycle with reference to the effects of progesterone and estrogen only
  • describe fertilisation and early development of the zygote simply in terms of the formation of a ball of cells which becomes implanted in the wall of the uterus
  • state the functions of the amniotic sac and the amniotic fluid
  • describe the function of the placenta and umbilical cord in relation to exchange of dissolved nutrients, gases and excretory products (structural details are not required)
  • discuss the spread of human immunodeficiency virus (HIV) and methods by which it may be controlled

Molecular Genetics

  • outline the relationship between DNA, genes and chromosomes
  • state the structure of DNA in terms of the bases, sugar and phosphate groups found in each of their nucleotides
  • state the rule of complementary base pairing
  • state that DNA is used to carry the genetic code, which is used to synthesise specific polypeptides (details of transcription and translation are not required)
  • state that each gene is a sequence of nucleotides, as part of a DNA molecule
  • explain that genes may be transferred between cells. Reference should be made to the transfer of genes between organisms of the same species or different species — transgenic plants or animals
  • briefly explain how a gene that controls the production of human insulin can be inserted into bacterial DNA to produce human insulin in medical biotechnology
  • discuss the social and ethical implications of genetic engineering, with reference to a named example

Heredity, Inheritance and Evolution

  • define a gene as a unit of inheritance and distinguish clearly between the terms gene and allele
  • explain the terms dominant, recessive, codominant, homozygous, heterozygous, phenotype and genotype
  • predict the results of simple crosses with expected ratios of 3:1 and 1:1, using the terms homozygous, heterozygous, F1 generation and F2 generation
  • explain why observed ratios often differ from expected ratios, especially when there are small numbers of progeny
  • use genetic diagrams to solve problems involving monohybrid inheritance (genetic diagrams involving autosomal linkage or epistasis are not required)
  • explain co-dominance and multiple alleles with reference to the inheritance of the ABO blood group phenotypes (A, B, AB and O) and the gene alleles (IA, IB and l°)
  • describe the determination of sex in humans — XX and XY chromosomes
  • describe mutation as a change in the structure of a gene such as in sickle cell anaemia, or in the chromosome number, such as the 47 chromosomes in the condition known as Down syndrome
  • name radiation and chemicals as factors which may increase the rate of mutation
  • describe the difference between continuous and discontinuous variation and give examples of each
  • state that variation and competition lead to differential survival of, and reproduction by, those organisms best fitted to the environment

 

MAN AND HIS ENVIRONMENT

Ecology

  •  briefly describe the non-cyclical nature of energy flow
  • explain the terms producer, consumer and trophic level in the context of food chains and food webs
  • explain how energy losses occur along food chains, and discuss the efficiency of energy transfer between trophic levels
  • describe and interpret pyramids of numbers and biomass
  • describe how carbon is cycled within an ecosystem and outline the role of forests and oceans as carbon sinks

Environment & Humans

  • evaluate the effects of
    – water pollution by sewage and by inorganic waste
    – pollution due to insecticides including bioaccumulation up food chains and impact on top carnivores
  • outline the roles of microorganisms in sewage treatment as an example of environmental biotechnology
  • discuss reasons for conservation of species with reference to the maintenance of biodiversity and how this is done, e.g. management of fisheries and management of timber production