Biology Pointers for Sem 1 Exam 2022-2023

Pointer for Sem 1 Exam 2022-2023 MCQ

Chapters 12 - 15

1. Glycolysis: glucose into pyruvate acid
2. Location of aerobic respiration: mitochondria
3. Fermentation
4. Light dependent reaction
5. Photophosphorylation
6. Photosynthesis
7. ATP is made up of
8. The ways ATP is generated
9. Net products of aerobic respiration
10. Reaction during photophosphorylation
11. Picture of chloroplast
12. Blood sugar level
13. Reabsorption of kidney
14. Homeostasis Glucagon
15. ADH
16. Endocrine
17. Graph about limiting factors of PHOTOSYNTHESIS
18. Saltatory conduction
19. Plant hormones
20. Products of respiration and materials of photosynthesis
21. Calvin Benson cycle (page 280 figure 13.13 statement what happened with this what happened with this )
22. Types of neurons
23. Reflex arc
24. Receptors in sense organs (tables of receptors and function)
25. Postsynaptic (receptor)
26. Roles of synapse (to transfer neurotransmitter to the post synaptic cleft, continue action potential,biar ga overloop 328)
27. Striated muscle structure
28. Muscle contraction (protein in muscle contraction )
29. Germination (gibberellin)
30. Cell elongation (hormone in plant) -> auxin

Structured Questions

31. Krebs cycle diagram

32. Link reaction and Krebs cycle 4 points

33. Kidney diagram (label and explain) 4 points

34. Action potential graph (label n explain)

35. Cross section of a leaf diagram 10 points

36. Ultrafiltration of nephron and blood vessels (8 points)

37. Abscisic acid (5 points)

38. Chemiosmosis in synthesis of ATP (2 points)

Chapter 12: Energy and Respiration

MCQ Questions:

1. Glycolysis

Understand bolded words in p.250

• • Phosphorylation: Glucose is activated through a reaction with ATP, producing a six-carbon sugar with two phosphate groups attached (fructose 1,6 bisphosphate). (two molecules of ATP are consumed per molecule of glucose respired -> converted to ADP + Pi)
  • Lysis (splitting): fructose 1,6 bisphosphate gets split, forming two molecules of triose phosphate (three-carbon sugar)
  • Oxidation: triose phosphate gets oxidised by the removal of hydrogen, catalysed by dehydrogenase enzyme. The enzyme works together with NAD (coenzyme) that accepts hydrogen. It then becomes reduced NAD.
  • ATP synthesis: this happens twice in the reaction by which each triose phosphate molecule is converted to pyruvate.

1. Location of aerobic respiration

GLYCOLYSIS takes place at the cytosol

LINK REACTION, KREB CYCLE (at the matrix) and ETC (oxidative phosphorylation) occurs at the inner membrane (cristae) of the mitochondria

1. Fermentation (p.259)

Fermentation occurs in anaerobic respiration, when there is no supply of oxygen. Oxygen usually acts as the final electron acceptor/ hydrogen acceptor. The oxidation of NADH and FADH cannot take place, so the supply of NAD doesn’t exist. This means glycolysis would not be able to take place (because NAD to NADH process is needed in phosphorylation of the triose monophosphate to triose biphosphate

Therefore, there needs to be another way to keep a continuous supply of pyruvate. Oxygen is replaced as the hydrogen acceptor

Types: alcoholic and lactic acid fermentation

Observe the diagram (glucose -> pyruvate (cannot continue into Krebs Cycle, but becomes alcohol or lactate)

REMEMBER the pathways of fermentation

Alcoholic fermentation (produces CO2); Hydrogen acceptor: ethanal; YEAST

2x pyruvate —CO2 removed→ 2x ethanal —alcohol dehydrogenase→ 2 x ethanol

NADH2→NADH

Lactate fermentation (no CO2); Hydrogen acceptor: lactate; VERTEBRATE

MUSCLE (HUMANS)

2x pyruvate —lactate dehydrogenase→2x lactate

NADH2→NADH

1. ATP is made up of

Adenosine, Ribose sugar, Three Phosphates

1. The ways ATP is generated

Page 245

1. Substrate-level phosphorylation

• Glycolysis: 2 ATP synthesised when 2 phosphates removed from triose biphosphate
• Krebs Cycle: 2 ATP synthesised when 2 x ATP produced during succinyl to succinate

1. Chemiosmosis in ETC

• Hydrogen and electron carriers pump protons into the cristae (intermembrane space) of the mitochondria, where the concentration gradient in hydrogen ions increase
• It creates a potential difference -> potential energy -> Hydrogen flows back to matrix, energy used for synthesis of ADP and Pi into ATP

Keyword: CHEMIOSMOSIS -> POTENTIAL GRAD, ATP SYNTHESIS

1. Net products of aerobic respiration

Page 252

Structured Questions:

31. Krebs cycle diagram

LABEL THE DIAGRAM

32. Link reaction and Krebs cycle

Write an essay and explain the steps

These processes occur in the matrix of the mitochondria. Pyruvate is actively transported from the cytosol into the matrix and the link reaction starts when carbon dioxide is removed from it through decarboxylation. Oxidation also occurs when hydrogen is removed and NAD acts as the hydrogen acceptor, reduced into NADH. The remaining is an acetyl group, which combines with coenzyme A into acetyl coenzyme A.

Then, the Krebs cycle starts when the acetyl coenzyme A combines with the product from the previous cycle: oxaloacetate, to form a 6-carbon compound citrate, and it converts to its isomer isocitrate. Then carbon dioxide is removed from isocitrate and NAD is reduced to NADH, becoming alpha ketoglutarate (5 carbons).

It then gets rid of carbon dioxide again, becoming a 4-carbon compound -> succinyl. Succinyl is converted into succinate, with the synthesis of ADP and Pi into ATP.

Succinate is then converted into fumarate, with FAD being reduced to FADH2.

Fumarate becomes malate, then malate is converted into oxaloacetate, with the reduction of NAD again into NADH.

LINK REACTION

1. DECARBOXYLATION: Carbon dioxide is removed from the pyruvate
2. OXIDATION: removal of hydrogen catalysed by dehydrogenase enzyme; NAD converted to NADH as it accepts the hydrogen
3. The product formed is the acetyl group, which combines with a coenzyme forming acetyl coenzyme A

KREBS CYCLE

1. Acetyl coenzyme A reacts with oxaloacetate, forming citrate
2. Two molecules of CO2 given off and NAD becomes reduced to NADH as the citrate becomes a 5 carbon (alpha-ketoglutarate) and then a 4 carbon (succinyl coenzyme A)
3. One molecule of ATP formed as succinyl coenzyme A is converted into succinate
4. FAD becomes reduced to FADH2, as succinate is converted into fumarate
5. NAD becomes NADH again when malate into oxaloacetate

38. Chemiosmosis in synthesis of ATP (2 points)

Chemiosmosis is the final stage of aerobic respiration, when the hydrogen atoms are transported along a series of carriers, from NADH or FADH2 to be combined with Oxygen to form water. Oxygen is the FINAL ELECTRON ACCEPTOR.

As electrons pass between the carriers in the etc, energy is released and the energy is used for ADP and Pi to be synthesised into ATP.

Carrier proteins (sequence of hydrogen carriers and electron carriers) use the energy of oxidation to pump protons into the intermembrane space of the mitochondria, where they cause the pH to drop and the concentration gradient to increase. There is a potential difference, therefore there is potential energy.

When the protons flow back to the matrix, the potential energy is used to synthesise ATP.

Chapter 13: Photosynthesis

MCQ Questions:

1. Light dependent reaction

Mention the substrate and the product (Page 279 product and roles)

Substrate: water, NADP, ADP, Phosphate

Products: ATP and NADPH, oxygen as waste product

3

1. Photophosphorylation

Page 279 read about it

1. Photosynthesis

Case study; read the question

1. Reaction during photophosphorylation

Page 279

1. Picture of chloroplast

Label a diagram in page 269

1. Graph about limiting factors of PHOTOSYNTHESIS

How they become limiting factors (light, carbon dioxide)

If there is not enough carbon dioxide, photosynthesis cannot occur

• At high light intensity, temperature has a higher effect on photosynthesis rate because light dependent reactions are highly temperature sensitive
• At low light intensity, temperature has little effect on photosynthesis
• When light is maximum and carbon dioxide is not much, the limiting factor is carbon dioxide so it already occurs at maximum rate

1. Products of respiration and materials of photosynthesis

It’s quite tricky but it’s easy; Study about aerobic respiration in plants, product is related between respiration and photosynthesis

Photosynthesis provides glucose as the product, which is then used in aerobic respiration.

1. Calvin Benson cycle

Figure 13.13 you have to read and understand the process

Not about diagram, understand the diagram

Statement; what happened with this, what happened with this….

Carbon dioxide combines with RuBP using an enzyme (Rubisco) to form a 6 carbon molecule that immediately splits into two 3-carbon molecules → 2 G3Ps

The G3Ps are reduced to triose phosphates, and as it happens, ATP becomes ADP + Pi and NADPH is oxidised to NADP.

For every 5 triose phosphates (5 x 3 = 15), 3 RuBP are formed again (3 x 5)

Structured Questions:

35. Cross section of a leaf diagram (10 points)

Homeostasis in plants, coordination in plants

Transport in plants

Page 162 about the figure 7.21

Page 144 about figure 7.2 (diagram of leaf)

Explain process and relate it with structure

Page 304 find structure that relate to function give example (podocytes have feet like structure, afferent and efferent arteriole

​​

FUNCTIONS:

• Guard cells: regulate transpiration by opening and closing the stomata
• Stomata: open and close to regulate temperature, moisture, etc
• Cuticle: contains wax and hair to trap moist air and regulate the temperature, reduce water loss when water is scarce
• Upper epidermis
• Lower epidermis
• Transfer cells: protein pumps transfer sucrose
• Palisade mesophyll cells: have chloroplasts arrange vertically to maximise capturing of sunlight
• Spongy mesophyll: contains spaces that maximise gas exchange of carbon dioxide and oxygen

Chapter 14: Homeostasis

MCQ Questions:

1. Blood sugar level

Page 294

Read about it; He gives a statement which one is correct

When blood glucose is high (hypoglycaemia), the beta cells of the islets of Langerhans in the pancreas secrete insulin, an enzyme that triggers glycogenesis, Glucose is converted into glycogen in places like muscles (but not the brain, there is no glycogen reserve in the brain). Insulin also triggers the conversion of glucose to fatty acids in the liver.

When blood glucose is low (hyperglycaemia), the alpha cells secrete glucagon, an enzyme that triggers gluconeogenesis, when glycogen is converted back to glucose and reduces rate of respiration to prevent much loss of glucose

1. Reabsorption of kidney (Which steps do reabsorption occur and what substances are reabsorbed in each step?)

Step 2: Reabsorption in the proximal convoluted tube

• Active transport of sugars, amino acids, etc.
• Facilitated diffusion of ions
• Pinocytosis of proteins

Step 5: Reabsorption of water in the collecting duct

• Water is reabsorbed through aquaporins in the collecting duct back into the medulla and then is returned to the bloodstream and body

1. Homeostasis Glucagon

Glucagon causes glycogen to be converted back to glucose as well as reduces rate of respiration.

1. ADH

What happens to the body when ADH exists?

KEYWORDS: Aquaporins, water reabsorption, volume of urine

Antidiuretic hormone is secreted when the water content of the blood is low.

• It changes the permeability of the cell walls of the collecting duct
• Aquaporin-2 (channel that can open, selectively permeable to water) opens as a response to ADH
• Rate of water diffusion (increases)
• Presence of ADH ensures that a max volume of water can be reabsorbed into the medulla

Low water content: ADH is secreted (antidiuretic) to prevent dilute urine, but instead, produces a more concentrated urine and increase water reabsorption

1. Endocrine System

TRUE OR FALSE

Pages 294 and 318

Study endocrine in chapters 14 and 15

Difference between?

Page 294 info

• Endocrine system and nervous system are coordinated by the pituitary gland, working in tandem with the brain’s hypothalamus
• Communicates by chemical messengers transmitted in the bloodstream
• Hormones ‘broadcast’ all over the body but only influence target cells
• Cause changes in metabolic activity
• Long lasting effects
• Effects take around many minutes, several hours, or longer

Page 318 info

• Hormones are the chemical messengers in the endocrine system
• Secreted from the cells in glands known as endocrine glands
• Contain capillary networks that specialised secretory cells that make and release hormones
• Released into blood stream and transported around the body
• Target organs
• Cells on target organs have specific receptor molecules where the hormone binds
• Hormone works by triggering changes to specific metabolic reactions in their target organs
• CIrculate in the bloodstream only briefly; liver breaks them down, excreted
• Hormones work by causing changes in metabolism over an extended period of time

Structured Questions:

33. Kidney diagram (4 points)

Labelling only the diagram

(left most is the renal artery, right to it is renal vein, bowman’s capsule, proximal convoluted tube, distal convoluted tube, collecting duct, loop of Henle

‘

36. Ultrafiltration of nephron and blood vessels (8 points - 4 STRUCTURES RELATED TO FUNCTION)

Explain process and relate with structure page 304 (structure related with function, give example to show the connection)

• Afferent and efferent arterioles in the Bowman’s capsule: the afferent arteriole is wider than the efferent arteriole, which creates a high blood pressure for ultrafiltration. The afferent can also dilate or constrict to influence rate of ultrafiltration. Efferent is smaller to increase pressure of blood (hydrostatic pressure)
• Podocytes: they have feet-like structures, leaving narrow slits and acts as a barrier to large, important proteins
• Basement membrane: filtration barrier, prevents important materials from being part of the urine and lost from the body
• Endothelial cells: regulation of blood flow in the kidneys and acts as a filtration barrier

Chapter 15: Control and Coordination

MCQ Questions:

1. Saltatory conduction

Explain (jumping2 node of ranviers)

There is myelin sheath wrapped around the axon, where action potential cannot pass through. This forces the action potential to ‘jump’ rather than pass through the entire long axon, shortening the time of impulse transfer.

1. Plant hormones

Make comparison of auxin, gibberellin, abscisic acid (ADA)

• Auxin: promotes plant growth (loosen polysaccharide and cellulose myofibrils so plants can grow taller, easier)
• Gibberellin: germination of seeds (cause seeds to germinate when there is water)
• Abscisic acid: plant hormone

1. Types of neurones

Sensory, intermediate, motor neurones

1. Reflex arc

Page 321 figure 15.4

1. Receptors in sense organs

Table of receptors 322 table 15.1 (light, touch, which location)

1. Postsynaptic

What happens in the postsynaptic?

Neurotransmitter binds onto the binding site / receptor (neurotransmitter receptor opens the sodium channel) Action potential is generated

1. Roles of synapse

Page 328 Roles of synapse → transmit of impulses, delay the information to prevent overload

• Filter out low-level stimuli
• Prevents overstimulation
• Flexibility of responses
• Allow information integration

1. Striated muscle structure

Diagram of the structure, Page 333

One example of the structure

Sarcomere, sarcolemma, sarcoplasmic reticulum, t-tubule, harus tau

1. Muscle contraction

Page 332

Information is quite tricky, it’s easy but because the trickiness, during muscle contraction, Understand about the proteins in muscle contraction actin myosin, tropomyosin, troponin

1. Germination

Gibberellin Page 340

Gibberellin in the embryo, when exposed to water, moves to the protein store through diffusion and activates germination. Hydrolytic enzymes catalyse the mobilisation of the food reserve, releasing sugars, amino acids, and fatty acids for germination and growth

1. Cell elongation (hormone in plant) -> Auxin
   1. Hydrogen go to cell wall
   2. When H+ fill cell wall, pH go down cuz acidic
   3. Hydrogen bond bond disturbed -sir Radit said
   4. Cellulose fibre exposed (loosen up not close)
      1. “Low pH triggers breakage of cross-links between cellulose microfibril and binding polysaccharides”
   5. Enzymes can easily attack the glycosidic bond
      1. “Hydrolytic enzymes attack exposed binding polysaccharides”
   6. Break them apart (the bonds)
   7. The cell wall can expand now
      1. “Wall resistance to stretching is decreased – turgor of cell causes stretching/elongation of cell wall”
   8. Thus elongation happens

Structured Questions:

34. Action potential graph

Labelling action potential graph (like the one in the test) and explaining what happens

• Part A: Resting potential

Potential gradient is maintained, outside is less positive than the inside (difference of -70mV) because while potassium enters and sodium exits through active transport at the same rate, the potassium is transferred back out through facilitated diffusion and sodium back inside. However, the potassium membrane is more permeable, so more potassium ions exit, thus outside is less positive.

At this stage, no impulse is transmitted at all.

• Part B: Depolarization

An impulse is transferred, triggered by stimulus at a receptor cell. Energy of stimulus opens sodium channels, so sodium enters and the inside becomes more positive.

• Part B.5: Action potential

An action potential is generated and passes

• Part C: Repolarization

After action potential passes, the potassium channel opens so potassium exits and the interior becomes less positive again

• Part D: Hyperpolarization

Becomes very negative lower than resting potential

• After Part D: back to resting potential

35. Abscisic acid (5 points)

• Origin: mature leaves, dormant seeds, ripe fruits and seeds
• Roles
  • It induces bud and seed dormancy
  • Stress hormone
  • Triggers the closing of stomata
• It is synthesised in most organs of mature plants, in tiny amounts (mature leaves, etc.)