IB SL Bio Correction

26

D

explain each of the feeding types:

Autotrophs (chemoautotrophs, photoautotrophs)

Heterotrophs (consumers, detritoveres, saprotrophs)

Mixotrophs

CAutotrophs (“self-feeders”)

• Organisms that synthesize their own organic molecules from simple inorganic substances (e.g., CO₂ and water).

• Examples: Plants, algae, some bacteria.

Types of Autotrophs:

a) Photoautotrophs → Use light energy to synthesize organic molecules.

• Example: Plants, cyanobacteria (photosynthetic bacteria).

b) Chemoautotrophs → Use chemical energy from inorganic compounds (e.g., sulfur, iron).

• Example: Nitrifying bacteria in soil.

2. Heterotrophs (“other-feeders”)

• Organisms that obtain organic molecules by consuming other organisms.

• Examples: Humans, animals, fungi.

Types of Heterotrophs:

a) Consumers → Ingest living or recently killed organic material.

• Example: Humans, lions, cows.

b) Detritivores → Ingest non-living organic matter (decomposing plant/animal material).

• Example: Earthworms, dung beetles.

c) Saprotrophs → Externally digest dead organic material by secreting digestive enzymes and absorbing nutrients.

• Example: Fungi, bacteria.

3. Mixotrophs (“both-feeders”)

• Organisms that can switch between autotrophic and heterotrophic modes of nutrition.

• Example: Euglena (a unicellular organism that photosynthesizes but can also consume food).

Different stages of meiosis

Meiosis

• Purpose: Produces genetically unique haploid gametes (sperm/egg).

• Occurs in: Sex organs (ovaries/testes in humans).

• Phases:

1. Interphase: DNA replication (chromosomes double).

2. Meiosis I:

• Prophase I: Homologous chromosomes pair up & crossing over occurs (genetic variation).

• Metaphase I: Homologous pairs line up in the middle.

• Anaphase I: Homologous chromosomes separate.

• Telophase I & Cytokinesis: 2 daughter cells form.

3. Meiosis II: (Like mitosis but with half the DNA)

• Prophase II: No DNA replication.

• Metaphase II: Chromosomes line up.

• Anaphase II: Sister chromatids separate.

• Telophase II & Cytokinesis: 4 genetically unique haploid cells form.

A (maltose is made of two glucose molecules, while sucrose is made of one glucose and one fructose molecule. in the diagram, molecules are different)

A

B

C

C

A

Describe where the potassium and sodium ions are at different phases of nerve impulse translation

A

B

C

B

B

detail blood clotting step by step

1. platelets (detect damage, release clotting factors)

2. clotting factors (activate enzymes leading to thrombin production)

3. thrombin (enzyme, converts fibrinogen to fibrin)

4. fibrinogen (soluble protein, becomes fibrin)

5. fibrin (insoluble protein, forms clot through fibrin mesh)

People Can Take Funny Falls

Where is FSH secreted from and what is is role

Pituitary gland + stimulates follicle development in ovaries and estrogen

Where is estrogen from and what does it do

Developing follicle + rebuilds uterine lining, inhibits FSH, stimulates LH

Where is LH from and what does it do

Pituitary gland + triggers ovulation, promotes corpus luteum

Where is progesterone from and what does it do

Corpus luteum + maintains endometrium, inhibits LH and FSH

Explain the menstruation phase (when, what happens with dif hormones)

Days 1-5

low estrogen + progesterone —> uterine lining sheds

FSH rises —> new follicle starts developing

Explain the follicular phase (when and what)

days 1-13

FSH stimulates follicle growth

Estrogen rises, rebuilding endometrium lining

Describe ovulation (when and what)

Day 14

High estrogen, LH sugre, egg released

Explain the literal haste (when and what)

Days 15-28

LH causes follicle to become corpus luteum

CL secretes progesterone, which maintains lining

If no fertilisation progesterone and estrogen fall

Exalting how enzymes lower activation energy

1. Stabilising transition state of a reaction

2. Weakening bonds in a sbstrate so they are broken more easily

Explain why DNA replication is semi-conservative

Each new DNA molecule is mad of one original strand and one new synthesised strand

C

B

What does the RER do?

• Synthesizes and processes proteins for export or membrane insertion.

• Studded with ribosomes.

what does the SER do

4. Smooth Endoplasmic Reticulum (SER)

• Synthesizes lipids, steroids, and detoxifies drugs.

• No ribosomes attached.

what does the golgi apparatus do

5. Golgi Apparatus

• Modifies, sorts, and packages proteins/lipids into vesicles.

• Involved in secretion and lysosome formation.

what does the centriole do

13. Centrioles (animal cells)

• Involved in cell division (spindle formation).

A

A

C

Outline how a dipeptide is formed

• two amni acids form during a condensation reaction

• the amine group (-NH(2) of one amino acid and the carboxyl group (-COOH) of another

• forms a peptide bond and releases water

C

A

explain gel electrophoresis purpose and steps

Gel electrophoresis is a technique used to separate DNA fragments according to their size. The process involves the following steps:

1. DNA is extracted.

2. Isolation and amplification of DNA.

3. DNA is added to the gel wells.

4. Electric current is applied to the gel.

5. DNA bands are separated by size.

6. DNA bands are stained.

D

D

explain IVF process in terms of what happens in two steps (drugs, and artificial hormones)

1. Initial drug treatment:

   • Women are given drugs to suppress their natural menstrual cycle.

   • This prevents natural fluctuations in hormones like FSH (Follicle Stimulating Hormone) and LH, so doctors can take full control.

2. Artificial hormone treatment:

   • High doses of FSH are given to stimulate multiple follicles to mature.

   • This leads to multiple ovulations, increasing the number of eggs that can be collected.

what makes maltose?

glucose + glucose

what makes sucrose

glucose + fructose

what makes lactose

glucose and galactose

describe the structure of amylose (its a starch)

linear, unbranched (slower energy). alpha, 1-4 glycosidic bonds. energy store in plants, stored in plants

describe the structure of amylopectin (its a starch)

branched, alpha 1-4 and alpha 1-6 glycosidic bonds. more compact and branched (faster enregy). energy store in plants, stored in plants

describe glycogen structure (found in animals)

• highly branched

• alpha 1-4 and alpha 1-6 glycosidic bonds

• stored in animals

• fast release energy

• store energy in humans

the more branches = easier to break down = faster energy

describe cellulose structure

• straight unbranched chains

• beta- 1,4 glycosid

strucuturally differentiate between saturated fats and unsaturated fats

• saturated = no double bonds, straight chains

• unsatureated = at least one double bond, causing a kink, making them more fluid

explain one structural advantage of the phospholipid bilayer forming a membrane

has hydrophillic heads and hydrophobic tails, allowing it to form a selectively permeable barrier in an aqueos environment.

what is the role of aquaporins in cells?

channel proteins that facilitate rapid water movement acorss membranes

differentiate between niche and habitat

• niche = role and position a species plays, (what it eats, where it lives, how it interacts)

• habiitat = physical place it could survive

two features of desert plants to reduce evalporation / transpiration

• thick cuticle (reduces evaporation)

• sunken stomatoa (traps moisture to reduce transpiration)

list the main macromolecule bonds

• carbohydrates —> glycosidic

• proteins —> peptides

• lipids —> ester

differentiate between saturated and unsaturated fats in regards to melting point, room temp state, found in, health impact, function, examples

• melting point (s - higher, u lower)

• room temp state (solid, liquid)

• found in (animal fats/dairy, plant oils/fish fats)

• health impact (increase ldl (bad), increase HDL (good)

• function (energy storage/insulation, energy source/membrane fluidity)

• examples (butter/ palm oil, nuts/seeds)

what’s an animal adaption to preveent wwater loss

kangeroo rats —> concentrated urine and few sweat glands