Weeds: JAMB Agricultural Science Questions, Answers & Notes

What Weeds covers in the JAMB Agricultural Science syllabus

A weed is any plant growing where it is not wanted. Weeds harm crops by competing for water, nutrients, light and space (reducing yield), harbouring pests and diseases, and contaminating produce; some (like Striga) are parasitic, attaching to crops and drawing their nutrients. Weeds are annual (one-year life cycle) or perennial (many years, harder to control). Control methods include manual/mechanical (hand-pulling, hoeing), chemical (herbicides — selective kill weeds not crops, non-selective kill all plants), biological (natural enemies), and cultural (mulching, crop rotation, good spacing); integrated weed management combines several methods. Early weeding matters most, since weeds compete strongly during a crop's early growth. Herbicides must be applied safely, following instructions with protective gear.

For Weeds, JAMB expects you to be able to:

• Define weeds and explain how they harm crops
• Classify weeds (annual/perennial, parasitic) and give examples
• Describe control methods: manual, mechanical, chemical, biological, cultural, integrated

Key facts & revision notes: Weeds

These are the recurring points our Weeds questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• A weed is any plant growing where it is not wanted (an unwanted plant).
• Weeds compete with crops for water, nutrients, light and space, reducing yield.
• Annual weeds complete their life cycle within one year.
• Perennial weeds live for many years and are usually harder to control.
• Manual/mechanical control uses hand-pulling, hoeing or mechanical tools to remove weeds.
• Herbicides are chemicals used to control/kill weeds (chemical control).
• Biological control uses natural enemies (insects, animals, pathogens) to control weeds.
• Cultural control uses good farming practices (mulching, rotation, spacing) to suppress weeds.
• Mulching covers the soil, blocking light and suppressing weed germination and growth.
• Weeds can harbour pests and diseases that then attack crops.
• A selective herbicide kills weeds while leaving the crop unharmed.
• A non-selective herbicide kills all vegetation it contacts (used for clearing).
• Weed seeds and parts can contaminate harvested produce, lowering its quality and value.
• Many weeds spread rapidly by producing large numbers of seeds.
• Integrated weed management combines cultural, mechanical, biological and chemical methods.
• Grasses like spear grass (Imperata) are common weeds; the maize crop is not a weed.
• Weeds cause the greatest damage in the crop's early growth, so early weeding is important.
• Parasitic weeds like Striga attach to crops and draw nutrients from them, severely reducing yield.
• Herbicides should be applied following instructions and using protective equipment for safety.
• Weed control protects crops from competition and pests, improving yield and quality.

Worked examples

Three Weeds questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Weeds is tested in JAMB Agricultural Science

Our Weeds bank holds 20 questions (1 easy, 9 medium, 10 hard). JAMB Agricultural Science typically returns to Weeds year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Weeds questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Weeds. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Agricultural Science item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Weeds is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Weeds

The errors that cost marks on Weeds are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Weeds actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Weeds part of the JAMB Agricultural Science syllabus?

Yes. Weeds is a recognised topic in the JAMB Agricultural Science syllabus, covering define weeds and explain how they harm crops. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Weeds questions can I practise on Belmadeng?

There are 20 original, JAMB-standard Weeds questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Weeds?

A weed is any plant growing where it is not wanted. Weeds harm crops by competing for water, nutrients, light and space (reducing yield), harbouring pests and diseases, and contaminating produce; some (like Striga) are parasitic, attaching to crops and drawing their nutrients. Weeds are annual (one-…

How do I answer Weeds questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Weeds. Practising timed Weeds questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Agricultural Science Weeds questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Weeds questions free without signing up?

Right here — tap “Start Weeds practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Agricultural Science syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.