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Asalam.o.alikum dear students specially CAIE STUDENTS OF PAKISTAN all you know that by this time in July 2021 you have to appear in only one paper of "BIOLOGY 5090" which is paper 1 (Multiple choice question).We have very short time to recall all syllabus but Don't worry about your exam's preparation.
I am coming up with past papers solution with complete explanation. I will upload 1 video daily monday to friday.INSHA ALLAH
Stay tune with me for O level Biology exams preparation.

Watch my previous video to ensure your A* grade :-)
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#5090

O LEVEL BIOLOGY 5090 YEAR 2010 PAPER 1 VARIENT 1 Asalam.o.alikum dear students specially CAIE STUDENTS OF PAKISTAN all you know that by this time in July 2021 you have to appear in only one paper of "BIOLOG...

🌱Root hair cell:
🌱Function:
🔹To absorb water and dissolve minerals from soil
🌱Adaptation:
🔹Extension,protrusion to increase the surface area
🔹Large vacuole to absorb and hold more and more water
🔹Absence of chloroplast to provide more space to vacuole
🔹Mitochondria to genetate energy for active transport of minerals

Transport across the cell membrane
Passive Transport:high to low concentration
Active Transport:low to high concentration
Learning and interaction With Ms Aisha Qadir

Human Excretory System

🔹Kidneys:organ for filtration,reabsorption and urine formation
🔹Ureter:tubes arise from each kidneys and take urine from kidneys to urinary bladder
🔹Urinary bladder:pouch like structure to hold urine and to reabsorb some water
🔹Urethra:opening to release urine surrounded by sphincter muscles which are voluntary in nature .
(But in infants and elderly people sphincter muscles are sometimes become involuntary)

🔹Kidneys:
📌Reddish ,brown ,bean shaped structure
📌Location:The kidneys are a pair of bean-shaped organs on either side of your spine, below your ribs and behind your belly.
📌Each kidney is about 4 or 5 inches long, roughly the size of a large fist.

🔹Structure of Kidneys:

📌Cortex:outer part
📌Medulla:inner part contain pyramids
📌Pyramids:cone shaped structures bearing nephrons
📌Renal Pelvis:its the point where all pyramids open and give their urine .Renal pelvis attach with ureter
📌Hilus:region from where
Renal artery and vein enter

🔹Nephron:

📌Functional unit of kidneys

🔹Structure of nephrons:
📌Glomerulus:afferent arterioles branched to form dense network of blood capillaries which form ball like structure
📌Bownman capsule:cup shape structure hold glomerulus
📌Proximal convulated tubules:tube like structure going upward to downward filtration occur here
📌Loop of Henle:U shape structure for filtration and reabsorption of substance
📌Distal convulated tubules:tube like structure going downward to upward
📌Collecting duct:receive urine and open in renal pelvis.

🔹Functions of kidneys/nephron;
📌Filtration.
📌Reabsorption
And
📌urine formation




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Human Respiratory system
The system involves in exchange of gases from environment
🔷Air passages:
External nostrils
Nasal passage:have cilia and mucus producing cells to filter air from dust particles and pathogens
Internal nostrils
Pharynx:connect internal nostrils with trachea
Larynx:sound box
Trachea:Surrounded by C shape cartilage
Bronchus (Bronchi):trachea divided into 2 bronchi
Bronchioles:branches of bronchi
🔷Site of Gaseous Exchange
Alveoli in lungs:balloon or grapes like hollow structure surrounded by blood vessels
🔷Acccessory organs and tissues involves
Sternum:chest bone
Rib cage:protect lungs
Diaphragm:contract during inhalation to allow lungs to expand and relax during exhalation to reverse the effect
External intercoastal muscles:contract during exhalation move sternum upward and outward to create space for lung's expansion and relax during exhalation to reverse the effect
Internal intercoastal muscle:relax during inhalation and contract during exhalation
🔷Adaptations of Alveoli for gaseous exchange
Hollow: to hold air
Elastic:to increase the surface area to volume ratio
Surrounded by dense network of blood. capillaries:to take CO2 from blood and add O2 in blood
One cell thick epithelial lining :to reduce the blood gas barrier and allow quick diffusion
Lubricated in structure :allow better diffusion.














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2021-03-23 09-49-51.mkv

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